U.S. patent application number 17/572771 was filed with the patent office on 2022-04-28 for transmission device, transmission method, receiving device and receiving method.
The applicant listed for this patent is Sun Patent Trust. Invention is credited to Tomohiro KIMURA, Yutaka MURAKAMI, Mikihiro OUCHI.
Application Number | 20220131597 17/572771 |
Document ID | / |
Family ID | 1000006078919 |
Filed Date | 2022-04-28 |
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United States Patent
Application |
20220131597 |
Kind Code |
A1 |
OUCHI; Mikihiro ; et
al. |
April 28, 2022 |
TRANSMISSION DEVICE, TRANSMISSION METHOD, RECEIVING DEVICE AND
RECEIVING METHOD
Abstract
Provided is a frame configuration usable for both SISO
transmission and MISO and/or MIMO transmission. A frame
configurator of a transmission device configures a frame by
gathering data for SISO and configures a frame by gathering data
for MISO and/or MIMO data, thereby to improve the reception
performance (detection performance) of a reception device.
Inventors: |
OUCHI; Mikihiro; (Osaka,
JP) ; MURAKAMI; Yutaka; (Kanagawa, JP) ;
KIMURA; Tomohiro; (Osaka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sun Patent Trust |
New York |
NY |
US |
|
|
Family ID: |
1000006078919 |
Appl. No.: |
17/572771 |
Filed: |
January 11, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16844188 |
Apr 9, 2020 |
11258505 |
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17572771 |
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16456436 |
Jun 28, 2019 |
10700761 |
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16844188 |
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16016951 |
Jun 25, 2018 |
10396884 |
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16456436 |
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15659938 |
Jul 26, 2017 |
10033452 |
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16016951 |
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14755155 |
Jun 30, 2015 |
9749034 |
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15659938 |
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14126121 |
Dec 13, 2013 |
9106396 |
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PCT/JP2012/004034 |
Jun 21, 2012 |
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14755155 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04B 7/10 20130101; H04L
1/0083 20130101; H04B 7/0871 20130101; H04L 25/0222 20130101; H04B
7/0413 20130101; H04B 7/0689 20130101; H04L 25/0391 20130101; H04W
72/0446 20130101 |
International
Class: |
H04B 7/08 20060101
H04B007/08; H04B 7/06 20060101 H04B007/06; H04B 7/0413 20060101
H04B007/0413; H04L 1/00 20060101 H04L001/00; H04W 72/04 20060101
H04W072/04 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 24, 2011 |
JP |
2011-140790 |
Jun 24, 2011 |
JP |
2011-140791 |
Claims
1. A transmission device to transmit orthogonal frequency-division
multiplexing (OFDM) symbols, comprising: a signal processor
configured to generate a frame such that the frame includes
subframes arranged in a time axis, the subframes each consisting of
first to last OFDM symbols arranged in the time axis, one of the
first OFDM symbol and the last OFDM symbol being a subframe
boundary symbol, the first to last OFDM symbols including a first
data symbol and a second data symbol that are provided between the
first OFDM symbol and the last OFDM symbol in the time axis; and a
transmitter connected to the signal processor to generate a
transmission signal based on the frame, the transmission signal
being to he transmitted through an antenna, the transmitter being
configured to: insert pilots in the first to last OFDM symbols such
that (i) the first data symbol includes a first pilot corresponding
to a first subcarrier, and the first data symbol does not include a
second pilot corresponding to a second subcarrier, (ii) the second
data symbol includes the second pilot, and the second data symbol
does not include the first pilot, and (iii) the subframe boundary
symbol includes at least the first pilot and the second pilot; and
perform Inverse Fast Fourier Transform on the first to last OFDM
symbols to generate the transmission signal, wherein the frame
includes signaling data before the subframes.
2. A reception device to receive orthogonal frequency-division
multiplexing (OFDM) symbols, comprising: a receiver configured to
receive a transmission signal; and a signal processor connected to
the receiver to: perform Fast Fourier Transform on the transmission
signal to generate a frame, the frame including subframes arranged
in a time axis, the subframes each consisting of first to last OFDM
symbols which are arranged in the time axis and in which pilots are
inserted; and detect the pilots to decode the first to last OFDM
symbols, wherein one of the first OFDM symbol and the last OFDM
symbol is a subframe boundary symbol, the first to last OFDM
symbols include a first data symbol and a second data symbol that
are provided between the first OFDM symbol and the last OFDM symbol
n the time axis, in the transmission signal, the first data symbol
includes a first pilot corresponding to a first subcarrier, and the
first data symbol does not include a second pilot corresponding to
a second subcarrier, in the transmission signal, the second data
symbol includes the second pilot, and the second data symbol does
not include the first pilot, and in the transmission signal, the
subframe boundary symbol includes at least the pilot first pilot
and the second pilot; wherein the frame includes signaling data
before the subframes.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on applications No. 2011-140790
and No. 2011-140791 both filed in Japan on Jun. 24, 2011, the
contents of which are hereby incorporated by reference.
TECHNICAL FIELD
[0002] The present invention relates to a transmission device and a
reception device for communication using multiple antennas.
BACKGROUND ART
[0003] Conventional technology allows for a transmission device
enabling communications in SISO (Single-Input, Single-Output) and
MISO (Multiple-Input, Single-Output) systems (e.g., Non-Patent
Literature 14).
CITATION LIST
Patent Literature
[Patent Literature 1]
[0004] International Patent Application Publication No.
WO2005/050885
Non-Patent Literature
[Non-Patent Literature 1]
[0005] "Achieving near-capacity on a multiple-antenna channel" IEEE
Transaction on communications, vol. 51, no. 3, pp. 389-399, March
2003
[Non-Patent Literature 2]
[0006] "Performance analysis and design optimization of LDPC-coded
MIMO OFDM systems" IEEE Trans. Signal Processing, vol. 52, no. 2,
pp. 348-361, February 2004
[Non-Patent Literature 3]
[0007] "BER performance evaluation in 2.times.2 MIMO spatial
multiplexing systems under Rician fading channels" IEICE Trans.
Fundamentals, vol. E91-A, no. 10, pp. 2798-2807, October 2008
[Non-Patent Literature 4]
[0008] "Turbo space-time codes with time varying linear
transformations" IEEE
[0009] Trans. Wireless communications, vol. 6, no. 2, pp. 486-493,
February 2007
[Non-Patent Literature 5]
[0010] "Likelihood function for QR-MLD suitable for soft-decision
turbo decoding and its performance" IEICE Trans. Commun., vol.
E88-B, no. 1, pp. 47-57, January 2004
[Non-Patent Literature 6]
[0011] "A tutorial on `Parallel concatenated (Turbo) coding`,
`Turbo (iterative) decoding` and related topics" IEICE, Technical
Report IT98-51
[Non-Patent Literature 7]
[0012] "Advanced signal processing for PLCs: Wavelet-OFDM" Proc. of
IEEE International symposium on ISPLC 2008, pp. 187-192, 2008
[Non-Patent Literature 8]
[0013] D. J. Love and R. W. Heath Jr., "Limited feedback unitary
precoding for spatial multiplexing systems" IEEE Trans. Inf.
Theory, vol. 51, no. 8, pp. 2967-2976, August 2005
[Non-Patent Literature 9]
[0014] DVB Document A122, Framing structure, channel coding and
modulation for a second generation digital terrestrial television
broadcasting system (DVB-T2), June 2008
[Non-Patent Literature 10]
[0015] L. Vangelista, N. Benvenuto, and S. Tomasin "Key
technologies for next-generation terrestrial digital television
standard DVB-T2," IEEE Commun. Magazine, vol. 47, no. 10, pp.
146-153, October 2009
[Non-Patent Literature 11]
[0016] T. Ohgane, T. Nishimura, and Y. Ogawa, "Applications of
space division multiplexing and those performance in a MIMO
channel" IEICE Trans. Commun., vol. E88-B, no. 5, pp. 1843-1851,
May 2005
[Non-Patent Literature 12]
[0017] R. G. Gallager "Low-density parity-check codes," IRE Trans.
Inform. Theory, IT-8, pp. 21-28, 1962
[Non-Patent Literature 13]
[0018] D. J. C. Mackay, "Good error-correcting codes based on very
sparse matrices," IEEE Trans. Inform. Theory, vol. 45, no. 2, pp.
399-431, March 1999.
[Non-Patent Literature 14]
[0019] ETSI EN 302 307, "Second generation framing structure,
channel coding and modulation systems for broadcasting, interactive
services, news gathering and other broadband satellite
applications" v. 1.1.2, June 2006
[Non-Patent Literature 15]
[0020] Y.-L. Ueng, and C.-C. Cheng "A fast-convergence decoding
method and memory-efficient VLSI decoder architecture for irregular
LDPC codes in the IEEE 802.16e standards" IEEE VTC-2007 Fall, pp.
1255-1259
[Non-Patent Literature 16]
[0021] S. M. Alamouti "A simple transmit diversity technique for
wireless communications" IEEE J. Select. Areas Commun., vol. 16,
no. 8, pp. 1451-1458, October 1998
[Non-Patent Literature 17]
[0022] V. Tarokh, H. Jafrkhani, and A. R. Calderbank "Space-time
block coding for wireless communications: Performance results" IEEE
J. Select. Areas Commun., vol. 17, no. 3, no. 3, pp. 451-460, March
1999
SUMMARY OF INVENTION
[0023] The present invention aims to provide a frame configuration
that allows, when used in transmitting signals by switching between
SISO and MISO/MIMO, easy detection of the signals at the receiver
side.
[0024] According to the present invention, a transmission device is
for Single-Input, Single-Output (SISO), Multiple-Input,
Single-Output (MISO), and Multiple-Input, Multiple-Output (MIMO),
and the transmission device includes: a frame configurator
configuring a SISO frame by exclusively gathering data for SISO
from target data for transmission, and configuring a MISO/MIMO
frame by exclusively gathering either or both of data for MISO and
data for MIMO from the target data; and a transmitter transmitting
the SISO frame and the MISO/MIMO frame.
[0025] As above, the present invention provides a transmission
method, reception method, transmission device, and reception device
each allowing the receiver side to detect signals easily when the
signals are transmitted using SISO, MISO, and MIMO.
BRIEF DESCRIPTION OF DRAWINGS
[0026] FIG. 1 illustrates an example of a transmission and
reception device in a spatial multiplexing MIMO system.
[0027] FIG. 2 illustrates a sample frame configuration.
[0028] FIG. 3 illustrates an example of a transmission device
applying a phase changing method.
[0029] FIG. 4 illustrates another example of a transmission device
applying a phase changing method.
[0030] FIG. 5 illustrates another sample frame configuration.
[0031] FIG. 6 illustrates another sample phase changing method.
[0032] FIG. 7 illustrates a sample configuration of a reception
device.
[0033] FIG. 8 illustrates a sample configuration of a signal
processor in the reception device.
[0034] FIG. 9 illustrates another sample configuration of a signal
processor in the reception device.
[0035] FIG. 10 illustrates an iterative decoding method.
[0036] FIG. 11 illustrates sample reception conditions.
[0037] FIG. 12 illustrates a further example of a transmission
device applying a phase changing method.
[0038] FIG. 13 illustrates yet a further example of a transmission
device applying a phase changing method.
[0039] FIGS. 14A and 14B illustrate another sample frame
configuration.
[0040] FIGS. 15A and 15B illustrate another sample frame
configuration.
[0041] FIGS. 16A and 16B illustrate another sample frame
configuration.
[0042] FIGS. 17A and 17B illustrate another sample frame
configuration.
[0043] FIGS. 18A and 18B illustrate another sample frame
configuration.
[0044] FIGS. 19A and 19B illustrate examples of a mapping
method.
[0045] FIGS. 20A and 20B illustrate further examples of a mapping
method.
[0046] FIG. 21 illustrates a sample configuration of a weighting
unit.
[0047] FIG. 22 illustrates a sample symbol rearrangement
method.
[0048] FIG. 23 illustrates another example of a transmission and
reception device in a spatial multiplexing MIMO system.
[0049] FIGS. 24A and 24B illustrate sample BER characteristics.
[0050] FIG. 25 illustrates another sample phase changing
method.
[0051] FIG. 26 illustrates another sample phase changing
method.
[0052] FIG. 27 illustrates another sample phase changing
method.
[0053] FIG. 28 illustrates another sample phase changing
method.
[0054] FIG. 29 illustrates another sample phase changing
method.
[0055] FIG. 30 illustrates a sample symbol arrangement for a
modulated signal providing high received signal quality.
[0056] FIG. 31 illustrates a sample frame configuration for a
modulated signal providing high received signal quality.
[0057] FIG. 32 illustrates a sample symbol arrangement for a
modulated signal providing high received signal quality.
[0058] FIG. 33 illustrates a sample symbol arrangement for a
modulated signal providing high received signal quality.
[0059] FIG. 34 illustrates a variation in numbers of symbols and
slots needed per pair of encoded blocks when block codes are
used.
[0060] FIG. 35 illustrates another variation in numbers of symbols
and slots needed per pair of encoded blocks when block codes are
used.
[0061] FIG. 36 illustrates an overall configuration of a digital
broadcasting system.
[0062] FIG. 37 is a block diagram illustrating a sample
receiver.
[0063] FIG. 38 illustrates multiplexed data configuration.
[0064] FIG. 39 is a schematic diagram illustrating multiplexing of
encoded data into streams.
[0065] FIG. 40 is a detailed diagram illustrating a video stream as
contained in a PES packet sequence.
[0066] FIG. 41 is a structural diagram of TS packets and source
packets in the multiplexed data.
[0067] FIG. 42 illustrates PMT data configuration.
[0068] FIG. 43 illustrates information as configured in the
multiplexed data.
[0069] FIG. 44 illustrates the configuration of stream attribute
information.
[0070] FIG. 45 illustrates the configuration of a video display and
audio output device.
[0071] FIG. 46 illustrates a sample configuration of a
communications system.
[0072] FIGS. 47A and 47B illustrate sample symbol arrangements for
a modulated signal providing high received signal quality.
[0073] FIGS. 48A and 48B illustrate sample symbol arrangements for
a modulated signal providing high received signal quality.
[0074] FIGS. 49A and 49B illustrate sample symbol arrangements for
a modulated signal providing high received signal quality.
[0075] FIGS. 50A and 50B illustrate sample symbol arrangements for
a modulated signal providing high received signal quality.
[0076] FIG. 51 illustrates a sample configuration of a transmission
device.
[0077] FIG. 52 illustrates another sample configuration of a
transmission device.
[0078] FIG. 53 illustrates a further sample configuration of a
transmission device.
[0079] FIG. 54 illustrates yet a further sample configuration of a
transmission device.
[0080] FIG. 55 illustrates a baseband signal switcher.
[0081] FIG. 56 illustrates yet still a further sample configuration
of a transmission device.
[0082] FIG. 57 illustrates sample operations of a distributor.
[0083] FIG. 58 illustrates further sample operations of a
distributor.
[0084] FIG. 59 illustrates a sample communications system
indicating the relationship between base stations and
terminals.
[0085] FIG. 60 illustrates an example of transmit signal frequency
allocation.
[0086] FIG. 61 illustrates another example of transmit signal
frequency allocation.
[0087] FIG. 62 illustrates a sample communications system
indicating the relationship between a base station, repeaters, and
terminals.
[0088] FIG. 63 illustrates an example of transmit signal frequency
allocation with respect to the base station.
[0089] FIG. 64 illustrates an example of transmit signal frequency
allocation with respect to the repeaters.
[0090] FIG. 65 illustrates a sample configuration of a receiver and
transmitter in the repeater.
[0091] FIG. 66 illustrates a signal data format used for
transmission by the base station.
[0092] FIG. 67 illustrates yet still another sample configuration
of a transmission device.
[0093] FIG. 68 illustrates another baseband signal switcher.
[0094] FIG. 69 illustrates a sample weighting, baseband signal
switching, and phase changing method.
[0095] FIG. 70 illustrates a sample configuration of a transmission
device using an OFDM method.
[0096] FIGS. 71A and 71B illustrate another sample frame
configuration.
[0097] FIG. 72 further illustrates the numbers of slots and phase
changing values corresponding to a modulation method.
[0098] FIG. 73 further illustrates the numbers of slots and phase
changing values corresponding to a modulation method.
[0099] FIG. 74 illustrates the overall frame configuration of a
signal transmitted by a broadcaster using DVB-T2.
[0100] FIG. 75 illustrates two or more types of signals at the same
timestamp.
[0101] FIG. 76 illustrates still a further sample configuration of
a transmission device.
[0102] FIG. 77 illustrates an alternate sample frame
configuration.
[0103] FIG. 78 illustrates another alternate sample frame
configuration.
[0104] FIG. 79 illustrates a further alternate sample frame
configuration.
[0105] FIG. 80 illustrates yet a further alternate sample frame
configuration.
[0106] FIG. 81 illustrates yet another alternate sample frame
configuration.
[0107] FIG. 82 illustrates still another alternate sample frame
configuration.
[0108] FIG. 83 illustrates still a further alternate sample frame
configuration.
[0109] FIG. 84 further illustrates two or more types of signals at
the same timestamp.
[0110] FIG. 85 illustrates an alternate sample configuration of a
transmission device.
[0111] FIG. 86 illustrates an alternate sample configuration of a
reception device.
[0112] FIG. 87 illustrates another alternate sample configuration
of a reception device.
[0113] FIG. 88 illustrates yet another alternate sample
configuration of a reception device.
[0114] FIGS. 89A and 89B illustrate further alternate sample frame
configurations.
[0115] FIGS. 90A and 90B illustrate yet further alternate sample
frame configurations.
[0116] FIGS. 91A and 91B illustrate more alternate sample frame
configurations.
[0117] FIGS. 92A and 92B illustrate yet more alternate sample frame
configurations.
[0118] FIGS. 93A and 93B illustrate still further alternate sample
frame configurations.
[0119] FIG. 94 illustrates a sample frame configuration used when
space-time block codes are employed.
[0120] FIG. 95 illustrates an example of signal point distribution
for 16-QAM in the I-Q plane.
[0121] FIG. 96 indicates a sample configuration for a signal
generator when cyclic Q delay is applied.
[0122] FIG. 97 illustrates a first example of a generation method
for s1(t) and s2(t) when cyclic Q delay is used.
[0123] FIG. 98 indicates a sample configuration for a signal
generator when cyclic Q delay is applied.
[0124] FIG. 99 indicates a sample configuration for a signal
generator when cyclic Q delay is applied.
[0125] FIG. 100 illustrates a second example of a generation method
for s1(t) and s2(t) when cyclic Q delay is used.
[0126] FIG. 101 indicates a sample configuration for a signal
generator when cyclic Q delay is applied.
[0127] FIG. 102 indicates a sample configuration for a signal
generator when cyclic Q delay is applied.
[0128] FIG. 103A indicates restrictions pertaining to
single-antenna transmission and multi-antenna transmission in the
DVB-T2 standard, while FIG. 103B indicates a desirable future
standard.
[0129] FIG. 104 indicates a sample sub-frame configuration based on
the transmit antenna configuration.
[0130] FIG. 105 indicates a sample sub-frame configuration based on
the transmit antenna configuration.
[0131] FIG. 106 indicates the transmit frame configuration.
[0132] FIG. 107 illustrates an SP pilot example for a sub-frame
starting symbol and a sub-frame closing symbol.
[0133] FIG. 108A illustrates an actual (SISO) DVB-T2 service
network.
[0134] FIG. 108B illustrates a distributed-MISO system employing an
existing transmit antenna.
[0135] FIG. 108C illustrates a co-sited-MIMO configuration.
[0136] FIG. 108D illustrates a configuration in which
distributed-MISO and co-sited-MIMO are combined.
[0137] FIG. 109 indicates a sub-frame configuration example based
on the transmit antenna configuration (taking the polarization into
consideration).
[0138] FIG. 110 indicates the transmit frame configuration.
[0139] FIG. 111 indicates a sub-frame configuration example based
on the transmit antenna configuration (taking the transmission
power into consideration).
[0140] FIG. 112 indicates the transmit frame configuration.
[0141] FIG. 113 indicates a sub-frame configuration example based
on the transmit antenna configuration (taking the polarization and
transmission power into consideration).
[0142] FIG. 114 indicates the transmit frame configuration.
DESCRIPTION OF EMBODIMENTS
(Inventor Discoveries)
[0143] MIMO (Multiple-Input, Multiple-Output) is an example of a
conventional communication system using multiple antennas. In
multi-antenna communication, of which MIMO is typical, multiple
transmission signals are each modulated, and each modulated signal
is simultaneously transmitted from a different antenna in order to
increase the transmission speed of the data.
[0144] FIG. 23 illustrates a sample configuration of a transmission
and reception device having two transmit antennas and two receive
antennas, and using two transmit modulated signals (transmit
streams). In the transmission device, encoded data is interleaved,
the interleaved data is modulated, and frequency conversion and the
like are performed to generate transmission signals, which are then
transmitted from antennas. In this case, the scheme for
simultaneously transmitting different modulated signals from
different transmit antennas at the same timestamp and on a common
frequency is spatial multiplexing MIMO.
[0145] In this context, Patent Literature 1 suggests using a
transmission device provided with a different interleaving pattern
for each transmit antenna. That is, the transmission device from
FIG. 23 should use two distinct interleaving patterns performed by
two interleavers Om and Tub). As for the reception device,
Non-Patent Literature 1 and Non-Patent Literature 2 describe
improving reception quality by iteratively using soft values for
the detection method (by the MIMO detector of FIG. 23).
[0146] As it happens, models of actual propagation environments in
wireless communications include NLOS (Non Line-Of-Sight), typified
by a Rayleigh fading environment, and LOS (Line-Of-Sight), typified
by a Rician fading environment. When the transmission device
transmits a single modulated signal, and the reception device
performs maximal ratio combination on the signals received by a
plurality of antennas and then demodulates and decodes the
resulting signals, excellent reception quality can be achieved in a
LOS environment, in particular in an environment where the Rician
factor is large. The Rician factor represents the received power of
direct waves relative to the received power of scattered waves.
However, depending on the transmission system (e.g., a spatial
multiplexing MIMO system), a problem occurs in that the reception
quality deteriorates as the Rician factor increases (see Non-Patent
Literature 3).
[0147] FIGS. 24A and 24B illustrate an example of simulation
results of the BER (Bit Error Rate) characteristics (vertical axis:
BER, horizontal axis: SNR (signal-to-noise ratio) for data encoded
with LDPC (low-density parity-check) codes and transmitted over a
2.times.2 (two transmit antennas, two receive antennas) spatial
multiplexing MIMO system in a Rayleigh fading environment and in a
Rician fading environment with Rician factors of K=3, 10, and 16
dB. FIG. 24A gives the Max-Log approximation-based log-likelihood
ratio (i.e., Max-log APP, where APP is the a posteriori
probability) BER characteristics without iterative phase detection
(see Non-Patent Literature 1 and Non-Patent Literature 2), while
FIG. 24B gives the Max-log APP BER characteristic with iterative
phase detection (see Non-Patent Literature 1 and Non-Patent
Literature 2) (number of iterations: five). FIGS. 24A and 24B
clearly indicate that, regardless of whether or not iterative phase
detection is performed, reception quality degrades in the spatial
multiplexing MIMO system as the Rician factor increases. Thus, the
problem of reception quality degradation upon stabilization of the
propagation environment in the spatial multiplexing MIMO system,
which does not occur in a conventional single-modulation signal
system, is unique to the spatial multiplexing MIMO system.
[0148] Broadcast or multicast communication is a service that must
be applied to various propagation environments. The radio wave
propagation environment between the broadcaster and the receivers
belonging to the users is often a LOS environment. When using a
spatial multiplexing MIMO system having the above problem for
broadcast or multicast communication, a situation may occur in
which the received electric field strength is high at the reception
device, but in which degradation in reception quality makes service
reception impossible. In other words, in order to use a spatial
multiplexing MIMO system in broadcast or multicast communication in
both the NLOS environment and the LOS environment, a MIMO system
that offers a certain degree of reception quality is desirable.
[0149] Non-Patent Literature 8 describes a method of selecting a
codebook used in precoding (i.e. a precoding matrix, also referred
to as a precoding weight matrix) based on feedback information from
a communication party. However, Non-Patent Literature 8 does not at
all disclose a method for precoding in an environment in which
feedback information cannot be acquired from the other party, such
as in the above broadcast or multicast communication.
[0150] On the other hand, Non-Patent Literature 4 discloses a
method for switching the precoding matrix over time. This method is
applicable when no feedback information is available. Non-Patent
Literature 4 discloses using a unitary matrix as the precoding
matrix, and switching the unitary matrix at random, but does not at
all disclose a method applicable to degradation of reception
quality in the above-described LOS environment. Non-Patent
Literature 4 simply recites hopping between precoding matrices at
random. Obviously, Non-Patent Literature 4 makes no mention
whatsoever of a precoding method, or a structure of a precoding
matrix, for remedying degradation of reception quality in a LOS
environment.
[0151] An object of the present invention is to provide a MIMO
system that improves reception quality in a LOS environment.
[0152] Embodiments of the present invention are described below
with reference to the accompanying drawings.
Embodiment 1
[0153] The following describes, in detail, a transmission method, a
transmission device, a reception method, and a reception device
pertaining to the present Embodiment.
[0154] Before beginning the description proper, an outline of
transmission schemes and decoding schemes in a conventional spatial
multiplexing MIMO system is provided.
[0155] FIG. 1 illustrates the structure of an Nt.times.Nr spatial
multiplexing MIMO system. An information vector z is encoded and
interleaved. The encoded bit vector u=(u.sub.1, . . . , u.sub.Nt)
is obtained as the interleave output. Here, u.sub.i=(u.sub.i1, . .
. , u.sub.iM) (where M is the number of transmitted bits per
symbol). For a transmit vector s=(s.sub.1, . . . , S.sub.Nt), a
received signal s.sub.i=map(u.sub.i) is found for transmit antenna
#i. Normalizing the transmit energy, this is expressible as
E{|s.sub.i|.sup.2}=E.sub.s/Nt (where E.sub.s is the total energy
per channel). The receive vector y=(y.sub.1, . . . y.sub.Nr).sup.T
is expressed in Math. 1 (formula 1), below.
[ Math . .times. 1 ] y = ( y 1 , .times. , y Nr ) T = H NtNr
.times. s + n ( formula .times. .times. 1 ) ##EQU00001##
[0156] Here, H.sub.NtNr is the channel matrix, n=(n.sub.1, . . . ,
n.sub.Nr) is the noise vector, and the average value of n.sub.i is
zero for independent and identically distributed (i.i.d) complex
Gaussian noise of variance .sigma..sup.2. Based on the relationship
between transmitted symbols introduced into a receiver and the
received symbols, the probability distribution of the received
vectors can be expressed as Math. 2 (formula 2), below, for a
multi-dimensional Gaussian distribution.
[ Math . .times. 2 ] p ( y .times. u ) - 1 ( 2 .times. .pi..sigma.
2 ) N r .times. exp - ( 1 2 .times. .sigma. 2 .times. y - H .times.
s .function. ( u ) 2 ) ( formula .times. .times. 2 )
##EQU00002##
[0157] Here, a receiver performing iterative decoding is
considered. Such a receiver is illustrated in FIG. 1 as being made
up of an outer soft-in/soft-out decoder and a MIMO detector. The
log-likelihood ratio vector (L-value) for FIG. 1 is given by Math.
3 (formula 3) through Math. 5 (formula 5), as follows.
[ Math . .times. 3 ] L .function. ( u ) = ( L .function. ( u 1 ) ,
.times. , L .function. ( u N t ) ) T ( formula .times. .times. 3 )
[ Math . .times. 4 ] L .function. ( u i ) = ( L .function. ( u i
.times. .times. 1 ) , .times. , L .function. ( u iM ) ) ( formula
.times. .times. 4 ) [ Math . .times. 5 ] L .function. ( u i .times.
j ) = ln .times. .times. P .function. ( u i .times. j = + 1 ) P
.function. ( u i .times. j = - 1 ) ( formula .times. .times. 5 )
##EQU00003##
(Iterative Detection Method)
[0158] The following describes the MIMO signal iterative detection
performed by the N.sub.t.times.N.sub.r spatial multiplexing MIMO
system. The log-likelihood ratio of u.sub.mn is defined by Math. 6
(formula 6).
[ Math . .times. 6 ] L ( u mn .times. y ) = ln .times. P .function.
( u mn = + 1 .times. y ) P .function. ( u mn = - 1 | y ) ( formula
.times. .times. 6 ) ##EQU00004##
[0159] Through application of Bayes' theorem, Math. 6 (formula 6)
can be expressed as Math. 7 (formula 7).
.times. [ Math . .times. 7 ] ##EQU00005## L .function. ( u mn y ) =
ln .times. p .function. ( y u mn = + 1 ) .times. P .function. ( u
mn = + 1 ) .times. / .times. p .function. ( y ) p .function. ( y u
mn = - 1 ) .times. P .function. ( u mn = - 1 ) .times. / .times. p
.function. ( y ) = ln .times. P .function. ( u mn = + 1 ) P
.function. ( u mn = - 1 ) + ln .times. p .function. ( y u mn = + 1
) p .function. ( y u mn = - 1 ) = ln .times. P .function. ( u mn =
+ 1 ) P .function. ( u mn = - 1 ) + ln .times. .SIGMA. U mn , + 1
.times. p .function. ( y u ) .times. p .function. ( u u mn )
.SIGMA. U mn , - 1 .times. p .function. ( y u ) .times. p
.function. ( u u mn ) ( formula .times. .times. 7 )
##EQU00005.2##
[0160] Note that U.sub.mn, .+-.1={u|u.sub.mn=.+-.1}. Through the
approximation ln.SIGMA.aj.about.max ln a.sub.j, Math. 7 (formula 7)
can be approximated as Math. 8 (formula 8). The symbol .about. is
herein used to signify approximation.
.times. [ Math . .times. 8 ] ##EQU00006## L .function. ( u mn y )
.apprxeq. ln .times. P .function. ( u mn = + 1 ) P .function. ( u
mn = - 1 ) + max Umn , + 1 .times. { ln .times. .times. p
.function. ( y u ) + P .function. ( u u mn ) } - max Umn , - 1
.times. { ln .times. .times. p .function. ( y u ) + P .function. (
u u mn ) } ( formula .times. .times. 8 ) ##EQU00006.2##
(formula 8)
[0161] In Math. 8 (formula 8), P(u|u.sub.mn) and ln P(u|u.sub.mn)
can be expressed as follows.
.times. [ Math . .times. 9 ] .times. P .function. ( u u mn ) = .PI.
( ij ) .noteq. ( mn ) .times. P .function. ( u ij ) = .PI. ( ij )
.noteq. ( mn ) .times. exp .function. ( u ij .times. L .function. (
u ij ) 2 ) exp .function. ( L .function. ( u ij ) 2 ) + exp
.function. ( - L .function. ( u ij ) 2 ) ( formula .times. .times.
9 ) .times. [ Math . .times. 10 ] .times. ln .times. .times. P
.function. ( u u mn ) = ( ij .times. ln .times. .times. P
.function. ( u ij ) ) - ln .times. .times. P .function. ( u mn ) (
formula .times. .times. 10 ) .times. [ Math . .times. 11 ] ln
.times. .times. P .function. ( u ij ) .times. = 1 2 .times. u ij
.times. P .function. ( u ij ) - ln .function. ( exp .function. ( L
.function. ( u ij ) 2 ) + exp .function. ( - L .function. ( u ij )
2 ) ) .times. .apprxeq. 1 2 .times. u ij .times. L .function. ( u
ij ) - 1 2 .times. L .function. ( u ij ) .times. .times. for
.times. .times. L .function. ( u ij ) > 2 .times. = L .function.
( u ij ) 2 .times. ( u ij .times. sign .function. ( L .function. (
u ij ) ) - 1 ) ( formula .times. .times. 11 ) ##EQU00007##
[0162] Note that the log-probability of the equation given in Math.
2 (formula 2) can be expressed as Math. 12 (formula 12).
[ Math . .times. 12 ] ##EQU00008## ln .times. .times. P .function.
( y u ) = - N r 2 .times. ln .function. ( 2 .times. .pi..sigma. 2 )
- 1 2 .times. .sigma. 2 .times. y - Hs .function. ( u ) 2 ( formula
.times. .times. 12 ) ##EQU00008.2##
[0163] Accordingly, given Math. 7 (formula 7) and Math. 13 (formula
13), the posterior L-value for the MAP or APP (a posteriori
probability) can be can be expressed as follows.
[ Math . .times. 13 ] ##EQU00009## L .function. ( u mn y ) = ln
.times. .SIGMA. U mn , + 1 .times. exp .times. { - 1 2 .times.
.sigma. 2 .times. y - Hs .function. ( u ) 2 + ij .times. ln .times.
.times. P .function. ( u ij ) } .SIGMA. U mn , - 1 .times. exp
.times. { - 1 2 .times. .sigma. 2 .times. y - Hs .function. ( u ) 2
+ ij .times. ln .times. .times. P .function. ( u ij ) } ( formula
.times. .times. 13 ) ##EQU00009.2##
[0164] This is hereinafter termed iterative APP decoding. Also,
given Math. 8 (formula 8) and Math. 12 (formula 12), the posterior
L-value for the Max-log APP can be can be expressed as follows.
.
.times. [ Math . .times. 14 ] L .function. ( u mn .times. y )
.apprxeq. max Umn , + 1 .times. { .PSI. .function. ( u , y , L
.function. ( u ) ) } - max Umn , - 1 .times. { .PSI. .function. ( u
, y , L .function. ( u ) ) } ( formula .times. .times. 14 ) .times.
[ Math . .times. 15 ] .times. .PSI. .function. ( u , y , L
.function. ( u ) ) = - 1 2 .times. .sigma. 2 .times. y - Hs
.function. ( u ) 2 + ij .times. ln .times. .times. P .function. ( u
ij ) ( formula .times. .times. 15 ) ##EQU00010##
[0165] This is hereinafter referred to as iterative Max-log APP
decoding. As such, the external information required by the
iterative decoding system is obtainable by subtracting prior input
from Math. 13 (formula 13) or from Math. 14 (formula 14).
(System Model)
[0166] FIG. 23 illustrates the basic configuration of a system
related to the following explanations. The illustrated system is a
2.times.2 spatial multiplexing MIMO system having an outer decoder
for each of two streams A and B. The two outer decoders perform
identical LDPC encoding. (Although the present example considers a
configuration in which the outer encoders use LDPC codes, the outer
encoders are not restricted to the use of LDPC as the
error-correcting codes. The example may also be realized using
other error-correcting codes, such as turbo codes, convolutional
codes, or LDPC convolutional codes. Further, while the outer
encoders are presently described as individually configured for
each transmit antenna, no limitation is intended in this regard. A
single outer encoder may be used for a plurality of transmit
antennas, or the number of outer encoders may be greater than the
number of transmit antennas.) The system also has interleavers
(.pi..sub.a, .pi..sub.b) for each of the streams A and B. Here, the
modulation method is 2.sup.h-QAM (i.e., h bits transmitted per
symbol).
[0167] The receiver performs iterative detection (iterative APP (or
Max-log APP) decoding) of MIMO signals, as described above. The
LDPC codes are decoded using, for example, sum-product
decoding.
[0168] FIG. 2 illustrates the frame configuration and describes the
symbol order after interleaving. Here, (i.sub.a,j.sub.a) and
(i.sub.b,j.sub.b) can be expressed as follows.
[Math. 16]
(i.sub.a, j.sub.a)=.pi..sub.a(.OMEGA..sub.ia, ja.sup.a) (formula
16)
[Math. 17]
(i.sub.b, j.sub.b)=.pi..sub.b(.OMEGA..sub.ib, jb.sup.a) (formula
17)
[0169] Here, i.sub.a and i.sub.b represent the symbol order after
interleaving, j.sub.a and j.sub.b represent the bit position in the
modulation method (where j.sub.a,j.sub.b=1, . . . h), .pi..sub.a
and .pi..sub.b represent the interleavers of streams A and B, and
.OMEGA..sup.a.sub.ia,ja and .OMEGA..sup.b.sub.ib,jb represent the
data order of streams A and B before interleaving. Note that FIG. 2
illustrates a situation where i.sub.a=i.sub.b.
(Iterative Decoding)
[0170] The following describes, in detail, the sum-product decoding
used in decoding the LDPC codes and the MIMO signal iterative
detection algorithm, both used by the receiver.
[0171] Sum-Product Decoding
[0172] A two-dimensional M.times.N matrix H={H.sub.mn} is used as
the check matrix for LDPC codes subject to decoding. For the set
[1,N]={1, 2 . . . N}, the partial sets A(m) and B(n) are defined as
follows.
[Math. 18]
A(m).ident.{n: H.sub.mn=1} (formula 18)
[Math. 19]
B(n).ident.{m: H.sub.mn=1} (formula 19)
[0173] Here, A(m) signifies the set of column indices equal to 1
for row m of check matrix H, while B(n) signifies the set of row
indices equal to 1 for row n of check matrix H. The sum-product
decoding algorithm is as follows. [0174] Step A-1 (Initialization):
For all pairs (m,n) satisfying H.sub.mn=1, set the prior log ratio
.beta..sub.mn=0. Set the loop variable (number of iterations)
l.sub.sum=1, and set the maximum number of loops l.sub.sum,max.
[0175] Step A-2 (Processing): For all pairs (m,n) satisfying
H.sub.mn=1 in the order m=1, 2, . . . M, update the extrinsic value
log ratio .alpha..sub.mn using the following update formula.
[0175] .times. [ Math . .times. 20 ] .alpha. mn = ( .PI. n '
.di-elect cons. A .function. ( m ) .times. \ .times. .times. n
.times. sign .function. ( .lamda. n ' + .beta. mn ' ) ) .times. f (
.PI. n ' .di-elect cons. A .function. ( m ) .times. \ .times.
.times. n .times. f .function. ( .lamda. n ' + .beta. mn ' ) ) (
formula .times. .times. 20 ) .times. [ Math . .times. 21 ] .times.
sign .function. ( x ) .ident. { 1 .times. x .gtoreq. 0 - 1 x < 0
( formula .times. .times. 21 ) .times. [ Math . .times. 22 ]
.times. f .function. ( x ) .ident. ln .times. exp .function. ( x )
+ 1 exp .function. ( x ) - 1 ( formula .times. .times. 22 )
##EQU00011##
[0176] where f is the Gallager function. .lamda..sub.n can then be
computed as follows. Step A-3 (Column Operations): For all pairs
(m,n) satisfying H.sub.mn=1 in the order n=1, 2, . . . N , update
the extrinsic value log ratio .beta..sub.mn using the following
update formula.
[ Math . .times. 23 ] ##EQU00012## .beta. mn = m ' .di-elect cons.
B .function. ( n ) .times. \ .times. m .times. .alpha. m ' .times.
n ( formula .times. .times. 23 ) ##EQU00012.2## [0177] Step A-4
(Log-likelihood Ratio Calculation): For n.di-elect cons.[1,N], the
log-likelihood ratio L.sub.n is computed as follows.
[0177] [ Math . .times. 24 ] ##EQU00013## L n = m ' .di-elect cons.
B .function. ( n ) .times. \ .times. m .times. .alpha. m ' .times.
n + .lamda. n ( formula .times. .times. 24 ) ##EQU00013.2## [0178]
Step A-5 (Iteration Count): If l.sub.sum<l.sub.sum,max, then
l.sub.sum is incremented and the process returns to step A-2.
Sum-product decoding ends when l.sub.sum=l.sub.sum,max.
[0179] The above describes one iteration of sum-product decoding
operations. Afterward, MIMO signal iterative detection is
performed. The variables m, n, .alpha..sub.mn, .beta..sub.mn,
.lamda..sub.n, and L.sub.n used in the above explanation of
sum-product decoding operations are expressed as m.sub.a, n.sub.a,
.alpha..sup.a.sub.mana, .beta..sup.a.sub.mana, .lamda..sub.na, and
L.sub.na for stream A and as m.sub.b, n.sub.b,
.alpha..sup.b.sub.mbnb, .beta..sup.b.sub.mbnb, .lamda..sub.nb, and
L.sub.nb for stream B.
(MIMO Signal Iterative Detection)
[0180] The following describes the calculation of .lamda..sub.n for
MIMO signal iterative detection.
[0181] The following formula is derivable from Math. 1 (formula
1).
[ Math . .times. 25 ] ##EQU00014## y .function. ( t ) = ( y 1
.function. ( t ) , y 2 .function. ( t ) ) T = H 22 .function. ( t )
.times. s .function. ( t ) + n .function. ( t ) ( formula .times.
.times. 25 ) ##EQU00014.2##
[0182] Given the frame configuration illustrated in FIG. 2, the
following functions are derivable from Math. 16 (formula 16) and
Math. 17 (formula 17).
[Math. 26]
n.sub.a=.OMEGA..sub.ia,ja.sup.a (formula 26)
[Math. 27]
n.sub.b=.OMEGA..sub.ib,jb.sup.b (formula 27)
[0183] where n.sub.a,n.sub.b .di-elect cons. [1,N]. For iteration k
of MIMO signal iterative detection, the variables .lamda..sub.na,
L.sub.na, .lamda..sub.nb, and L.sub.nb are expressed as
.lamda..sub.k,na, L.sub.k,na, .lamda..sub..kappa.,nb, and
L.sub.k,nb.
[0184] Step B-1 (Initial Detection; k=0) For initial wave
detection, .lamda..sub.o,na and .lamda..sub.0,nb are calculated as
follows.
For iterative APP decoding:
.times. [ Math . .times. 28 ] ##EQU00015## .lamda. 0 , n X = ln
.times. .SIGMA. U 0 , n X , + 1 .times. exp .times. { - 1 2 .times.
.sigma. 2 .times. y .function. ( i X ) - H 22 .function. ( i X )
.times. s .function. ( u .function. ( i X ) ) 2 } .SIGMA. U 0 , n X
, - 1 .times. exp .times. { - 1 2 .times. .sigma. 2 .times. y
.function. ( i X ) - H 22 .function. ( i X ) .times. s .function. (
u .function. ( i X ) ) 2 } ( formula .times. .times. 28 )
##EQU00015.2##
For iterative Max-log APP decoding:
.times. [ Math . .times. 29 ] .lamda. 0 , n X = max U 0 , n X , + 1
.times. { .PSI. .function. ( u .function. ( i X ) , y .function. (
i X ) ) } - max U 0 , n X , - 1 .times. { .PSI. .function. ( u
.function. ( i X ) , y .function. ( i X ) ) } ( formula .times.
.times. 29 ) .times. [ Math . .times. 30 ] .times. .PSI. .function.
( u .function. ( i X ) , y .function. ( i X ) ) = - 1 2 .times.
.sigma. 2 .times. y .function. ( i X ) - H 22 .function. ( i X )
.times. s .function. ( u .function. ( i X ) ) 2 ( formula .times.
.times. 30 ) ##EQU00016##
[0185] where X=a,b. Next, the iteration count for the MIMO signal
iterative detection is set to l.sub.mimo=0, with the maximum
iteration count being l.sub.mimo,max.
[0186] Step B-2 (Iterative Detection; Iteration k): When the
iteration count is k, Math. 11 (formula 11), Math. 13 (formula 13)
through Math. 15 (formula 15), Math. 16 (formula 16), and Math. 17
(formula 17) can be expressed as Math. 31 (formula 31) through
Math. 34 (formula 34), below. Note that (X,Y)=(a,b)(b,a).
For iterative APP decoding:
[ Math . .times. 31 ] .lamda. k , n X = L k - 1 , .OMEGA. iX , jX X
.function. ( u .OMEGA. iX , jX X ) + ln .times. .SIGMA. U i , n X ,
+ 1 .times. exp .times. { - 1 2 .times. .sigma. 2 .times. y
.function. ( i X ) - H 22 .function. ( i X ) .times. s .function. (
u .function. ( i X ) ) 2 + .rho. .function. ( u .OMEGA. iX , jX X )
} .SIGMA. U i , n X , - 1 .times. exp .times. { - 1 2 .times.
.sigma. 2 .times. y .function. ( i X ) - H 22 .function. ( i X )
.times. s .function. ( u .function. ( i X ) ) 2 + .rho. .function.
( u .OMEGA. iX , jX X ) } ( formula .times. .times. 31 ) [ Math .
.times. 32 ] .rho. .function. ( u .OMEGA. iX , jX X ) = .gamma. = 1
.times. .times. .gamma. .noteq. jX h .times. .times. L k - 1 ,
.OMEGA. iX , jX X .function. ( u .OMEGA. iX , jX X .times. ) 2
.times. ( u .OMEGA. iX , .gamma. X .times. sign .function. ( L k -
1 , .OMEGA. iX , .gamma. X .function. ( u .OMEGA. iX , .gamma. X )
) - 1 ) + .gamma. = 1 h .times. .times. L k - 1 , .OMEGA. iX , jX X
.function. ( u .OMEGA. iX , jX X .times. ) 2 .times. ( u .OMEGA. iX
, .gamma. X .times. sign .function. ( L k - 1 , .OMEGA. iX ,
.gamma. X .function. ( u .OMEGA. iX , .gamma. X ) ) - 1 ) ( formula
.times. .times. 32 ) ##EQU00017##
For iterative Max-log APP decoding:
.times. [ Math . .times. 33 ] .lamda. k , n X = L k - 1 , .OMEGA.
iX , jX X .function. ( u .OMEGA. iX , jX X ) + max U k , n X , + 1
.times. { .PSI. .function. ( n .function. ( i X ) , y .function. (
i X ) , .rho. .function. ( u .OMEGA. iX , jX X ) ) } - max U k , n
X , - 1 .times. { .PSI. .function. ( n .function. ( i X ) , y
.function. ( i X ) , .rho. .function. ( u .OMEGA. iX , jX X ) ) } (
formula .times. .times. 33 ) .times. [ Math . .times. 34 ] .PSI.
.function. ( u .function. ( i X ) , y .function. ( i X ) , .rho.
.function. ( u .OMEGA. iX , jX X ) ) = - 1 2 .times. .sigma. 2
.times. y .function. ( i X ) - H 22 .function. ( i X ) .times. s
.function. ( u .function. ( i X ) ) 2 + .rho. .function. ( u
.OMEGA. iX , jX X ) ( formula .times. .times. 34 ) ##EQU00018##
Step B-3 (Iteration Count and Codeword Estimation) If
l.sub.mimo<l.sub.mimo,max, then l.sub.mimo is incremented and
the process returns to step B-2. When l.sub.mimo=l.sub.mimo,max, an
estimated codeword is found, as follows.
[ Math . .times. 35 ] ##EQU00019## u ^ n X = { 1 .times. L l mimo ,
n X .gtoreq. 0 - 1 L l mimo , n X < 0 .times. .times. where
.times. .times. X = a , b . ( formula .times. .times. 35 )
##EQU00019.2##
[0187] FIG. 3 shows a sample configuration of a transmission device
300 pertaining to the present Embodiment. An encoder 302A takes
information (data) 301A and a frame configuration signal 313 as
input (which includes the error-correction method, encoding rate,
block length, and other information used by the encoder 302A in
error-correction coding of the data, such that the method
designated by the frame configuration signal 313 is used. The
error-correction method may be switched). In accordance with the
frame configuration signal 313, the encoder 302A performs
error-correction coding, such as convolutional encoding, LDPC
encoding, turbo encoding or similar, and outputs encoded data
303A.
[0188] An interleaver 304A takes the encoded data 303A and the
frame configuration signal 313 as input, performs interleaving,
i.e., rearranges the order thereof, and then outputs interleaved
data 305A. (Depending on the frame configuration signal 313, the
interleaving method may be switched.)
[0189] A mapper 306A takes the interleaved data 305A and the frame
configuration signal 313 as input and performs modulation, such as
(Quadrature Phase Shift Keying), 16-QAM (16-Quadradature Amplitude
Modulation), or 64-QAM (64-Quadrature Amplitude Modulation)
thereon, then outputs a baseband signal 307A. (Depending on the
frame configuration signal 313, the modulation method may be
switched.)
[0190] FIGS. 19A and 19B illustrate an example of a QPSK modulation
mapping method for a baseband signal made up of an in-phase
component I and a quadrature component Q in the IQ plane. For
example, as shown in FIG. 19A, when the input data are 00, then the
output is I=1.0, Q=1.0. Similarly, when the input data are 01, the
output is I=-1.0, Q=1.0, and so on. FIG. 19B illustrates an example
of a QPSK modulation mapping method in the IQ plane differing from
FIG. 19A in that the signal points of FIG. 19A have been rotated
about the origin to obtain the signal points of FIG. 19B.
Non-Patent Literature 9 and Non-Patent Literature 10 describe such
a constellation rotation method. Alternatively, the Cyclic Q Delay
described in Non-Patent Literature 9 and Non-Patent Literature 10
may also be adopted. An alternate example, distinct from FIGS. 19A
and 19B, is shown in FIGS. 20A and 20B, which illustrate a signal
point layout for 16-QAM in the IQ plane. The example of FIG. 20A
corresponds to FIG. 19A, while that of FIG. 20B corresponds to FIG.
19B.
[0191] An encoder 302B takes information (data) 301B and the frame
configuration signal 313 as input (which includes the
error-correction method, encoding rate, block length, and other
information used by the encoder 302B in error-correction coding of
the data, such that the method designated by the frame
configuration signal 313 is used. The error-correction method may
be switched). In accordance with the frame configuration signal
313, the encoder 302B performs error-correction coding, such as
convolutional encoding, LDPC encoding, turbo encoding or similar,
and outputs encoded data 303B.
[0192] An interleaver 304B takes the encoded data 303B and the
frame configuration signal 313 as input, performs interleaving,
i.e., rearranges the order thereof, and outputs interleaved data
305B. (Depending on the frame configuration signal 313, the
interleaving method may be switched.)
[0193] A mapper 306B takes the interleaved data 305B and the frame
configuration signal 313 as input and performs modulation, such as
QPSK, 16-QAM, or 64-QAM thereon, then outputs a baseband signal
307B. (Depending on the frame configuration signal 313, the
modulation method may be switched.)
[0194] A signal processing method information generator 314 takes
the frame configuration signal 313 as input and accordingly outputs
signal processing method information 315. The signal processing
method information 315 designates the fixed precoding matrix to be
used, and includes information on the pattern of phase changes used
for changing the phase.
[0195] A weighting unit 308A takes baseband signal 307A, baseband
signal 307B, and the signal processing method information 315 as
input and, in accordance with the signal processing method
information 315, performs weighting on the baseband signals 307A
and 307B, then outputs a weighted signal 309A. The weighting method
is described in detail, later.
[0196] A wireless unit 310A takes weighted signal 309A as input and
performs processing such as quadrature modulation, band limitation,
frequency conversion, amplification, and so on, then outputs
transmit signal 311A. Transmit signal 311A is then output as radio
waves by an antenna 312A.
[0197] A weighting unit 308B takes baseband signal 307A, baseband
signal 307B, and the signal processing method information 315 as
input and, in accordance with the signal processing method
information 315, performs weighting on the baseband signals 307A
and 307B, then outputs weighted signal 316B.
[0198] FIG. 21 illustrates the configuration of the weighting units
308A and 308B. The area of FIG. 21 enclosed in the dashed line
represents one of the weighting units. Baseband signal 307A is
multiplied by w11 to obtain w11s1(t), and multiplied by w21 to
obtain w21s1(t). Similarly, baseband signal 307B is multiplied by
w12 to obtain w12s2(t), and multiplied by w22 to obtain w22s2(t).
Next, z1(t)=w11s1(t)+w12s2(t) and z2(t)=w21s1(t)+w22s22(t) are
obtained. Here, as explained in Embodiment 1, s1(t) and s2(t) are
baseband signals modulated according to a modulation method such as
BPSK (Binary Phase Shift Keying), QPSK, 8-PSK (8-Phase Shift
Keying), 16-QAM, 32-QAM (32-Quadrature Amplitude Modulation),
64-QAM, 256-QAM 16-APSK (16-Amplitude Phase Shift Keying) and so
on.
[0199] Both weighting units perform weighting using a fixed
precoding matrix. The precoding matrix uses, for example, the
method of Math. 36 (formula 36), and satisfies the conditions of
Math. 37 (formula 37) or Math. 38 (formula 38), all found below.
However, this is only an example. The value of a is not restricted
to Math. 37 (formula 37) and Math. 38 (formula 38), and may take on
other values, e.g., .alpha.=1.
[0200] Here, the precoding matrix is
[ Math . .times. 36 ] ( w .times. .times. 11 w .times. .times. 12 w
.times. .times. 21 w .times. .times. 22 ) = 1 .alpha. 2 + 1 .times.
( e j .times. .times. 0 .alpha. .times. e j .times. .times. 0
.alpha. .times. e j .times. .times. 0 e j .times. .times. .pi. ) (
formula .times. .times. 36 ) ##EQU00020##
[0201] In Math. 36 (formula 36), above, .alpha. is given by:
[ Math . .times. 37 ] .alpha. = 2 + 4 2 + 2 ( formula .times.
.times. 27 ) ##EQU00021##
[0202] Alternatively, in Math. 36 (formula 36), above, a may be
given by:
[ Math . .times. 38 ] .alpha. = 2 + 3 + 5 2 + 3 - 5 ( formula
.times. .times. 38 ) ##EQU00022##
[0203] The precoding matrix is not restricted to that of Math. 36
(formula 36), but may also be as indicated by Math. 39 (formula
39).
[ Math . .times. 39 ] ( w .times. .times. 11 w .times. .times. 12 w
.times. .times. 21 w .times. .times. 22 ) = ( a b c d ) ( formula
.times. .times. 39 ) ##EQU00023##
[0204] In Math. 39 (formula 39), let a=Ae.sup.i.delta.11,
b=Be.sup.i.delta.12, c=Ce.sup.i.delta.21, and d=De.sup.i.delta.22,
Further, one of a, b, c, and d may be equal to zero. For example,
the following configurations are possible: (1) a may be zero while
b, c, and d are non-zero, (2) b may be zero while a, c, and d are
non-zero, (3) c may be zero while a, b, and d are non-zero, or (4)
d may be zero while a, b, and c are non-zero.
[0205] When any of the modulation method, error-correcting codes,
and the encoding rate thereof are changed, the precoding matrix may
also be set, changed, and fixed for use.
[0206] A phase changer 317B takes weighted signal 316B and the
signal processing method information 315 as input, then regularly
changes the phase of the signal 316B for output. This regular
change is a change of phase performed according to a predetermined
phase changing pattern having a predetermined period (cycle) (e.g.,
every n symbols (n being an integer, n.gtoreq.1) or at a
predetermined interval). The details of the phase changing pattern
are explained below, in Embodiment 4.
[0207] Wireless unit 310B takes post-phase change signal 309B as
input and performs processing such as quadrature modulation, band
limitation, frequency conversion, amplification, and so on, then
outputs transmit signal 311B. Transmit signal 311B is then output
as radio waves by an antenna 312B.
[0208] FIG. 4 illustrates a sample configuration of a transmission
device 400 that differs from that of FIG. 3. The points of
difference of FIG. 4 from FIG. 3 are described next.
[0209] An encoder 402 takes information (data) 401 and the frame
configuration signal 313 as input, and, in accordance with the
frame configuration signal 313, performs error-correction coding
and outputs encoded data 402.
[0210] A distributor 404 takes the encoded data 403 as input,
performs distribution thereof, and outputs data 405A and data 405B.
Although FIG. 4 illustrates only one encoder, the number of
encoders is not limited as such. The present invention may also be
realized using m encoders (m being an integer, m.gtoreq.1) such
that the distributor divides the encoded data created by each
encoder into two groups for distribution.
[0211] FIG. 5 illustrates an example of a frame configuration in
the time domain for a transmission device according to the present
Embodiment. Symbol 500_1 is a symbol for notifying the reception
device of the transmission scheme. For example, symbol 500_1
conveys information such as the error-correction method used for
transmitting data symbols, the encoding rate thereof, and the
modulation method used for transmitting data symbols.
[0212] Symbol 501_1 is for estimating channel fluctuations for
modulated signal z1(t) (where t is time) transmitted by the
transmission device. Symbol 502_1 is a data symbol transmitted by
modulated signal z1(t) as symbol number u (in the time domain).
Symbol 503_1 is a data symbol transmitted by modulated signal z1(t)
as symbol number u+1.
[0213] Symbol 501_2 is for estimating channel fluctuations for
modulated signal z2(t) (where t is time) transmitted by the
transmission device. Symbol 502_2 is a data symbol transmitted by
modulated signal z2(t) as symbol number u. Symbol 503_2 is a data
symbol transmitted by modulated signal z1(t) as symbol number
u+1.
[0214] Here, the symbols of z1(t) and of z2(t) having the same
timestamp (identical timing) are transmitted from the transmit
antenna using the same (shared/common) frequency .
[0215] The following describes the relationships between the
modulated signals z1(t) and z2(t) transmitted by the transmission
device and the received signals r1(t) and r2(t) received by the
reception device.
[0216] In FIG. 5, 504#1 and 504#2 indicate transmit antennas of the
transmission device, while 505#1 and 505#2 indicate receive
antennas of the reception device. The transmission device transmits
modulated signal z1(t) from transmit antenna 504#1 and transmits
modulated signal z2(t) from transmit antenna 504#2. Here, modulated
signals z1(t) and z2(t) are assumed to occupy the same
(shared/common) frequency (bandwidth). The channel fluctuations in
the transmit antennas of the transmission device and the antennas
of the reception device are h.sub.11(t), h.sub.12(t), h.sub.21(t),
and h.sub.22(t), respectively. Assuming that receive antenna 505#1
of the reception device receives received signal r1(t) and that
receive antenna 505#2 of the reception device receives received
signal r2(t), the following relationship holds.
[ Math . .times. 40 ] ( r .times. .times. 1 .times. ( t ) r .times.
.times. 2 .times. ( t ) ) = ( h 11 .function. ( t ) h 12 .function.
( t ) h 21 .function. ( t ) h 22 .function. ( t ) ) .times. ( z
.times. .times. 1 .times. ( t ) z .times. .times. 2 .times. ( t ) )
( formula .times. .times. 40 ) ##EQU00024##
[0217] FIG. 6 pertains to the weighting method (precoding method)
and the phase changing method of the present Embodiment. A
weighting unit 600 is a combined version of the weighting units
308A and 308B from FIG. 3. As shown, stream s1(t) and stream s2(t)
correspond to the baseband signals 307A and 307B of FIG. 3. That
is, the streams s1(t) and s2(t) are baseband signals made up of an
in-phase component I and a quadrature component Q conforming to
mapping by a modulation method such as QPSK, 16-QAM, and 64-QAM. As
indicated by the frame configuration of FIG. 6, stream s1(t) is
represented as s1(u) at symbol number u, as s1(u+1) at symbol
number u+1, and so forth. Similarly, stream s2(t) is represented as
s2(u) at symbol number u, as s2(u+1) at symbol number u+1, and so
forth. The weighting unit 600 takes the baseband signals 307A
(s1(t)) and 307B (s2(t)) as well as the signal processing method
information 315 from FIG. 3 as input, performs weighting in
accordance with the signal processing method information 315, and
outputs the weighted signals 309A (z1(t)) and 316B(z2'(t)) from
FIG. 3. The phase changer 317B changes the phase of weighted signal
316B(z2'(t)) and outputs post-phase change signal 309B(z2(t)).
[0218] Here, given vector W1=(w11,w12) from the first row of the
fixed precoding matrix F, z1(t) is expressible as Math. 41 (formula
41), below.
[Math. 41]
z1(t)=W1.times.(s1(t), s2(t)).sup.T (formula 41)
[0219] Similarly, given vector W2=(w21,w22) from the second row of
the fixed precoding matrix F, and letting the phase changing
formula applied by the phase changer by y(t), then z2(t) is
expressible as Math. 42 (formula 42), below.
[Math. 42]
z2(t)=y(t).times.W2.times.(s1(t), s2(t)).sup.T (formula 42)
[0220] Here, y(t) is a phase changing formula obeying a
predetermined method.
[0221] For example, given a period (cycle) of four and timestamp u,
the phase changing formula may be expressed as Math. 43 (formula
43), below.
[Math. 43]
y(u)=e.sup.j0 (formula 43)
[0222] Similarly, the phase changing formula for timestamp u+1 may
be, for example, as given by Math. 44 (formula 44).
[ Math . .times. 44 ] y .function. ( u + 1 ) = e j .times. .pi. 2 (
formula .times. .times. 44 ) ##EQU00025##
[0223] That is, the phase changing formula for timestamp u+k
generalizes to Math. 45 (formula 45).
[ Math . .times. 45 ] y .function. ( u + k ) = e j .times. k
.times. .times. .pi. 2 ( formula .times. .times. 45 )
##EQU00026##
[0224] Note that Math. 43 (formula 43) through Math. 45 (formula
45) are given only as an example of a regular change of phase.
[0225] The regular change of phase is not restricted to a period
(cycle) of four. Improved reception capabilities (the
error-correction capabilities, to be exact) may potentially be
promoted in the reception device by increasing the period (cycle)
number (this does not mean that a greater period (cycle) is better,
though avoiding small numbers such as two is likely ideal).
[0226] Furthermore, although Math. 43 (formula 43) through Math. 45
(formula 45), above, represent a configuration in which a change in
phase is carried out through rotation by consecutive predetermined
phases (in the above formula, every .pi./2), the change in phase
need not be rotation by a constant amount, but may also be random.
For example, in accordance with the predetermined period (cycle) of
y(t), the phase may be changed through sequential multiplication as
shown in Math. 46 (formula 46) and Math. 47 (formula 47). The key
point of the regular change of phase is that the phase of the
modulated signal is regularly changed. The phase changing degree
variance rate is preferably as even as possible, such as from -.pi.
radians to .pi. radians. However, given that this concerns a
distribution, random variance is also possible.
[ Math . .times. 46 ] e j .times. .times. 0 .fwdarw. e j .times.
.pi. 5 .fwdarw. e j .times. 2 .times. .pi. 5 .fwdarw. e j .times. 3
.times. .pi. 5 .fwdarw. e j .times. 4 .times. .pi. 5 .fwdarw. e j
.times. .times. .pi. .fwdarw. e j .times. 6 .times. .pi. 5 .fwdarw.
e j .times. 7 .times. .pi. 5 .fwdarw. e j .times. 8 .times. .pi. 5
.fwdarw. e j .times. 9 .times. .pi. 5 ( formula .times. .times. 46
) [ Math . .times. 47 ] e j .times. .pi. 5 .fwdarw. e j .times.
.times. .pi. .fwdarw. e j .times. 3 .times. .pi. 5 .fwdarw. e j
.times. .times. 2 .times. .pi. .fwdarw. e j .times. .pi. 4 .fwdarw.
e j .times. 3 4 .times. .pi. .fwdarw. e j .times. 5 .times. .pi. 4
.fwdarw. e j .times. 7 .times. .pi. 4 ( formula .times. .times. 47
) ##EQU00027##
[0227] As such, the weighting unit 600 of FIG. 6 performs precoding
using fixed, predetermined precoding weights, and the phase changer
317B changes the phase of the signal input thereto while regularly
varying the phase changing degree.
[0228] When a specialized precoding matrix is used in the LOS
environment, the reception quality is likely to improve
tremendously. However, depending on the direct wave conditions, the
phase and amplitude components of the direct wave may greatly
differ from the specialized precoding matrix, upon reception. The
LOS environment has certain rules. Thus, data reception quality is
tremendously improved through a regular change of transmit signal
phase that obeys those rules. The present invention offers a signal
processing method for improving the LOS environment.
[0229] FIG. 7 illustrates a sample configuration of a reception
device 700 pertaining to the present embodiment. Wireless unit
703_X receives, as input, received signal 702_X received by antenna
701_X, performs processing such as frequency conversion, quadrature
demodulation, and the like, and outputs baseband signal 704_X.
[0230] Channel fluctuation estimator 705_1 for modulated signal z1
transmitted by the transmission device takes baseband signal 704_X
as input, extracts reference symbol 501_1 for channel estimation
from FIG. 5, estimates the value of h.sub.11 from Math. 40 (formula
40), and outputs channel estimation signal 706_1.
[0231] Channel fluctuation estimator 705_2 for modulated signal z2
transmitted by the transmission device takes baseband signal 704_X
as input, extracts reference symbol 502_2 for channel estimation
from FIG. 5, estimates the value of h.sub.12 from Math. 40 (formula
40), and outputs channel estimation signal 706_1.
[0232] Wireless unit 703_Y receives, as input, received signal
702_Y received by antenna 701_Y, performs processing such as
frequency conversion, quadrature demodulation, and the like, and
outputs baseband signal 704_Y.
[0233] Channel fluctuation estimator 707_1 for modulated signal z1
transmitted by the transmission device takes baseband signal 704_Y
as input, extracts reference symbol 501_1 for channel estimation
from FIG. 5, estimates the value of h.sub.11 from Math. 40 (formula
40), and outputs channel estimation signal 708_1.
[0234] Channel fluctuation estimator 707_2 for modulated signal z2
transmitted by the transmission device takes baseband signal 704_Y
as input, extracts reference symbol 502_2 for channel estimation
from FIG. 5, estimates the value of h.sub.11 from Math. 40 (formula
40), and outputs channel estimation signal 708_2.
[0235] A control information decoder 709 receives baseband signal
704_X and baseband signal 704_Y as input, detects symbol 500_1 that
indicates the transmission scheme from FIG. 5, and outputs a
transmission method information signal 710 for the transmission
device.
[0236] A signal processor 711 takes the baseband signals 704_X and
704_Y, the channel estimation signals 706_1, 706_2, 708_1, and
708_2, and the transmission method information signal 710 as input,
performs detection and decoding, and then outputs received data
712_1 and 712_2.
[0237] Next, the operations of the signal processor 711 from FIG. 7
are described in detail. FIG. 8 illustrates a sample configuration
of the signal processor 711 pertaining to the present embodiment.
As shown, the signal processor 711 is primarily made up of an inner
MIMO detector, a soft-in/soft-out decoder, and a coefficient
generator. Non-Patent Literature 2 and Non-Patent Literature 3
describe the method of iterative decoding with this structure. The
MIMO system described in Non-Patent Literature 2 and Non-Patent
Literature 3 is a spatial multiplexing MIMO system, while the
present Embodiment differs from Non-Patent Literature 2 and
Non-Patent Literature 3 in describing a MIMO system that regularly
changes the phase over time, while using the precoding matrix.
Taking the (channel) matrix H(t) of Math. 36 (formula 36), then by
letting the precoding weight matrix from FIG. 6 be F (here, a fixed
precoding matrix remaining unchanged for a given received signal)
and letting the phase changing formula used by the phase changer
from FIG. 6 be Y(t) (here, Y(t) changes over time t), then the
receive vector R(t)=(r1(t),r2(t)).sup.T and the stream vector
S(t)=(s1(t),s2(t)).sup.T the following function is derived:
[ Math . .times. 48 ] R .function. ( t ) = H .function. ( t )
.times. Y .function. ( t ) .times. F .times. S .function. ( t )
where Y .function. ( t ) = ( 1 0 0 y .function. ( t ) ) ( formula
.times. .times. 48 ) ##EQU00028##
[0238] Here, the reception device may use the decoding methods of
Non-Patent Literature 2 and 3 on R(t) by computing
H(t).times.Y(t).times.F.
[0239] Accordingly, the coefficient generator 819 from FIG. 8 takes
a transmission method information signal 818 (corresponding to 710
from FIG. 7) indicated by the transmission device (information for
specifying the fixed precoding matrix in use and the phase changing
pattern used when the phase is changed) and outputs a signal
processing method information signal 820.
[0240] The inner MIMO detector 803 takes the signal processing
method information signal 820 as input and performs iterative
detection and decoding using the signal and the relationship
thereof to Math. 48 (formula 48). The operations thereof are
described below.
[0241] The processing unit illustrated in FIG. 8 must use a
processing method, as is illustrated in FIG. 10, to perform
iterative decoding (iterative detection). First, detection of one
codeword (or one frame) of modulated signal (stream) s1 and of one
codeword (or one frame) of modulated signal (stream) s2 are
performed. As a result, the soft-in/soft-out decoder obtains the
log-likelihood ratio of each bit of the codeword (or frame) of
modulated signal (stream) s1 and of the codeword (or frame) of
modulated signal (stream) s2. Next, the log-likelihood ratio is
used to perform a second round of detection and decoding. These
operations (referred to as iterative decoding (iterative
detection)) are performed multiple times . The following
explanations centre on the creation method of the log-likelihood
ratio of a symbol at a specific time within one frame.
[0242] In FIG. 8, a memory 815 takes baseband signal 801X
(corresponding to baseband signal 704_X from FIG. 7), channel
estimation signal group 802X (corresponding to channel estimation
signals 706_1 and 706_2 from FIG. 7), baseband signal 801Y
(corresponding to baseband signal 704_Y from FIG. 7), and channel
estimation signal group 802Y (corresponding to channel estimation
signals 708_1 and 708_2 from FIG. 7) as input, executes (computes)
H(t).times.Y(t).times.F from Math. 48 (formula 48) in order to
perform iterative decoding (iterative detection), and stores the
resulting matrix as a transformed channel signal group. The memory
815 then outputs the above-described signals as needed,
specifically as baseband signal 816X, transformed channel
estimation signal group 817X, baseband signal 816Y, and transformed
channel estimation signal group 817Y.
[0243] Subsequent operations are described separately for initial
detection and for iterative decoding (iterative detection).
[0244] (Initial Detection)
[0245] The inner MIMO detector 803 takes baseband signal 801X,
channel estimation signal group 802X, baseband signal 801Y, and
channel estimation signal group 802Y as input. Here, the modulation
method for modulated signal (stream) s1 and modulated signal
(stream) s2 is described as 16-QAM.
[0246] The inner MIMO detector 803 first computes
H(t).times.Y(t).times.F from the channel estimation signal groups
802X and 802Y, thus calculating a candidate signal point
corresponding to baseband signal 801X. FIG. 11 represents such a
calculation. In FIG. 11, each black dot is a candidate signal point
in the IQ plane. Given that the modulation method is 16-QAM, 256
candidate signal points exist. (However, FIG. 11 is only a
representation and does not indicate all 256 candidate signal
points.) Letting the four bits transmitted in modulated signal s1
be b0, b1, b2, and b3 and the four bits transmitted in modulated
signal s2 be b4, b5, b6, and b7, candidate signal points
corresponding to (b0, b1, b2, b3, b4, b5, b6, b7) are found in FIG.
11. The Euclidean squared distance between each candidate signal
point and each received signal point 1101 (corresponding to
baseband signal 801X) is then computed. The Euclidean squared
distance between each point is divided by the noise variance
G.sup.2.
[0247] Accordingly, Ex(b0, b1, b2, b3, b4, b5, b6, b7) is
calculated. That is, the Euclidean squared distance between a
candidate signal point corresponding to (b0, b1, b2, b3, b4, b5,
b6, b7) and a received signal point is divided by the noise
variance. Here, each of the baseband signals and the modulated
signals s1 and s2 is a complex signal.
[0248] Similarly, the inner MIMO detector 803 computes
H(t).times.Y(t).times.F from the channel estimation signal groups
802X and 802Y, calculates candidate signal points corresponding to
baseband signal 801Y, computes the Euclidean squared distance
between each of the candidate signal points and the received signal
points (corresponding to baseband signal 801Y), and divides the
Euclidean squared distance by the noise variance .sigma..sup.2.
Accordingly, E.sub.Y(b0, b1, b2, b3, b4, b5, b6, b7) is calculated.
That is, E.sub.Y is the Euclidean squared distance between a
candidate signal point corresponding to (b0, b1, b2, b3, b4, b5,
b6, b7) and a received signal point, divided by the noise
variance.
[0249] Next, Ex(b0, b1, b2, b3, b4, b5, b6, b7)+E.sub.Y(b0, b1, b2,
b3, b4, b5, b6, b7)=E(b0, b1, b2, b3, b4, b5, b6, b7) is
computed.
[0250] The inner MIMO detector 803 outputs E(b0, b1, b2, b3, b4,
b5, b6, b7) as the signal 804.
[0251] The log-likelihood calculator 805A takes the signal 804 as
input, calculates the log-likelihood of bits b0, b1, b2, and b3,
and outputs the log-likelihood signal 806A. Note that this
log-likelihood calculation produces the log-likelihood of a bit
being 1 and the log-likelihood of a bit being 0. The calculation
method is as shown in Math. 28 (formula 28), Math. 29 (formula 29),
and Math. 30 (formula 30), and the details thereof are given by
Non-Patent Literature 2 and 3.
[0252] Similarly, log-likelihood calculator 805B takes the signal
804 as input, calculates the log-likelihood of bits b4, b5, b6, and
b7, and outputs log-likelihood signal 806B.
[0253] A deinterleaver (807A) takes log-likelihood signal 806A as
input, performs deinterleaving corresponding to that of the
interleaver (the interleaver (304A) from FIG. 3), and outputs
deinterleaved log-likelihood signal 808A.
[0254] Similarly, a deinterleaver (807B) takes log-likelihood
signal 806B as input, performs deinterleaving corresponding to that
of the interleaver (the interleaver (304B) from FIG. 3), and
outputs deinterleaved log-likelihood signal 808B.
[0255] Log-likelihood ratio calculator 809A takes deinterleaved
log-likelihood signal 808A as input, calculates the log-likelihood
ratio of the bits encoded by encoder 302A from FIG. 3, and outputs
log-likelihood ratio signal 810A.
[0256] Similarly, log-likelihood ratio calculator 809B takes
deinterleaved log-likelihood signal 808B as input, calculates the
log-likelihood ratio of the bits encoded by encoder 302B from FIG.
3, and outputs log-likelihood ratio signal 810B.
[0257] Soft-in/soft-out decoder 811A takes log-likelihood ratio
signal 810A as input, performs decoding, and outputs a decoded
log-likelihood ratio 812A.
[0258] Similarly, soft-in/soft-out decoder 811B takes
log-likelihood ratio signal 810B as input, performs decoding, and
outputs decoded log-likelihood ratio 812B.
[0259] (Iterative Decoding (Iterative Detection), k Iterations)
[0260] The interleaver (813A) takes the k-1th decoded
log-likelihood ratio 812A decoded by the soft-in/soft-out decoder
as input, performs interleaving, and outputs an interleaved
log-likelihood ratio 814A. Here, the interleaving pattern used by
the interleaver (813A) is identical to that of the interleaver
(304A) from FIG. 3.
[0261] Another interleaver (813B) takes the k-1th decoded
log-likelihood ratio 812B decoded by the soft-in/soft-out decoder
as input, performs interleaving, and outputs interleaved
log-likelihood ratio 814B. Here, the interleaving pattern used by
the interleaver (813B) is identical to that of the other
interleaver (304B) from FIG. 3.
[0262] The inner MIMO detector 803 takes baseband signal 816X,
transformed channel estimation signal group 817X, baseband signal
816Y, transformed channel estimation signal group 817Y, interleaved
log-likelihood ratio 814A, and interleaved log-likelihood ratio
814B as input. Here, baseband signal 816X, transformed channel
estimation signal group 817X, baseband signal 816Y, and transformed
channel estimation signal group 817Y are used instead of baseband
signal 801X, channel estimation signal group 802X, baseband signal
801Y, and channel estimation signal group 802Y because the latter
cause delays due to the iterative decoding.
[0263] The iterative decoding operations of the inner MIMO detector
803 differ from the initial detection operations thereof in that
the interleaved log-likelihood ratios 814A and 814B are used in
signal processing for the former. The inner MIMO detector 803 first
calculates E(b0, b1, b2, b3, b4, b5, b6, b7) in the same manner as
for initial detection. In addition, the coefficients corresponding
to Math. 11 (formula 11) and Math. 32 (formula 32) are computed
from the interleaved log-likelihood ratios 814A and 814B. The value
of E(b0, b1, b2, b3, b4, b5, b6, b7) is corrected using the
coefficients so calculated to obtain E'(b0, b1, b2, b3, b4, b5, b6,
b7), which is output as the signal 804.
[0264] The log-likelihood calculator 805A takes the signal 804 as
input, calculates the log-likelihood of bits b0, b1, b2, and b3,
and outputs the log-likelihood signal 806A. Note that this
log-likelihood calculation produces the log-likelihood of a bit
being 1 and the log-likelihood of a bit being 0. The calculation
method is as shown in Math. 31 (formula 31) through Math. 35
(formula 35), and the details are given by Non-Patent Literature 2
and 3.
[0265] Similarly, log-likelihood calculator 805B takes the signal
804 as input, calculates the log-likelihood of bits b4, b5, b6, and
b7, and outputs log-likelihood signal 806B. Operations performed by
the deinterleaver onwards are similar to those performed for
initial detection.
[0266] While FIG. 8 illustrates the configuration of the signal
processor when performing iterative detection, this structure is
not absolutely necessary as good reception improvements are
obtainable by iterative detection alone. As long as the components
needed for iterative detection are present, the configuration need
not include the interleavers 813A and 813B. In such a case, the
inner MIMO detector 803 does not perform iterative detection.
[0267] The key point for the present Embodiment is the calculation
of H(t).times.Y(t).times.F. As shown in Non-Patent Literature 5 and
the like, QR decomposition may also be used to perform initial
detection and iterative detection.
[0268] Also, as indicated by Non-Patent Literature 11, MMSE
(Minimum Mean-Square Error) and ZF (Zero-Forcing) linear operations
may be performed based on H(t).times.Y(t).times.F when performing
initial detection.
[0269] FIG. 9 illustrates the configuration of a signal processor,
unlike that of FIG. 8, that serves as the signal processor for
modulated signals transmitted by the transmission device from FIG.
4. The point of difference from FIG. 8 is the number of
soft-in/soft-out decoders. A soft-in/soft-out decoder 901 takes the
log-likelihood ratio signals 810A and 810B as input, performs
decoding, and outputs a decoded log-likelihood ratio 902. A
distributor 903 takes the decoded log-likelihood ratio 902 as input
for distribution. Otherwise, the operations are identical to those
explained for FIG. 8.
[0270] As described above, when a transmission device according to
the present Embodiment using a MIMO system transmits a plurality of
modulated signals from a plurality of antennas, changing the phase
over time while multiplying by the precoding matrix so as to
regularly change the phase results in improvements to data
reception quality for a reception device in a LOS environment,
where direct waves are dominant, compared to a conventional spatial
multiplexing MIMO system.
[0271] In the present Embodiment, and particularly in the
configuration of the reception device, the number of antennas is
limited and explanations are given accordingly. However, the
Embodiment may also be applied to a greater number of antennas. In
other words, the number of antennas in the reception device does
not affect the operations or advantageous effects of the present
Embodiment.
[0272] Also, although LDPC codes are described as a particular
example, the present Embodiment is not limited in this manner,
Furthermore, the decoding method is not limited to the sum-product
decoding example given for the soft-in/soft-out decoder. Other
soft-in/soft-out decoding methods, such as the BCJR algorithm,
SOVA, and the Max-Log-Map algorithm may also be used. Details are
provided in Non-Patent Literature 6.
[0273] In addition, although the present Embodiment is described
using a single-carrier method, no limitation is intended in this
regard. The present Embodiment is also applicable to multi-carrier
transmission. Accordingly, the present Embodiment may also be
realized using, for example, spread-spectrum communications, OFDM,
SC-FDMA (Single Carrier Frequency-Division Multiple Access),
SC-OFDM, wavelet OFDM as described in Non-Patent Literature 7, and
so on. Furthermore, in the present Embodiment, symbols other than
data symbols, such as pilot symbols (preamble, unique word, and so
on) or symbols transmitting control information, may be arranged
within the frame in any manner.
[0274] The following describes an example in which OFDM is used as
a multi-carrier method.
[0275] FIG. 12 illustrates the configuration of a transmission
device using OFDM. In FIG. 12, components operating in the manner
described for FIG. 3 use identical reference numbers.
[0276] An OFDM-related processor 1201A takes weighted signal 309A
as input, performs OFDM-related processing thereon, and outputs
transmit signal 1202A. Similarly, OFDM-related processor 1201B
takes post-phase change signal 309B as input, performs OFDM-related
processing thereon, and outputs transmit signal 1202B.
[0277] FIG. 13 illustrates a sample configuration of the
OFDM-related processors 1201A and 1201B and onward from FIG. 12.
Components 1301A through 1310A belong between 1201A and 312A from
FIG. 12, while components 1301B through 1310B belong between 1201B
and 312B.
[0278] Serial-to-parallel converter 1302A performs
serial-to-parallel conversion on weighted signal 1301A
(corresponding to weighted signal 309A from FIG. 12) and outputs
parallel signal 1303A.
[0279] Reorderer 1304A takes parallel signal 1303A as input,
performs reordering thereof, and outputs reordered signal 1305A.
Reordering is described in detail later.
[0280] IFFT (Inverse Fast Fourier Transform) unit 1306A takes
reordered signal 1305A as input, applies an IFFT thereto, and
outputs post-IFFT signal 1307A.
[0281] Wireless unit 1308A takes post-IFFT signal 1307A as input,
performs processing such as frequency conversion and amplification,
thereon, and outputs modulated signal 1309A. Modulated signal 1309A
is then output as radio waves by antenna 1310A.
[0282] Serial-to-parallel converter 1302B performs
serial-to-parallel conversion on weighted signal 1301B
(corresponding to post-phase change 309B from FIG. 12) and outputs
parallel signal 1303B.
[0283] Reorderer 1304B takes parallel signal 1303B as input,
performs reordering thereof, and outputs reordered signal 1305B.
Reordering is described in detail later.
[0284] IFFT unit 1306B takes reordered signal 1305B as input,
applies an IFFT thereto, and outputs post-IFFT signal 1307B.
[0285] Wireless unit 1308B takes post-IFFT signal 1307B as input,
performs processing such as frequency conversion and amplification
thereon, and outputs modulated signal 1309B. Modulated signal 1309B
is then output as radio waves by antenna 1310A.
[0286] The transmission device from FIG. 3 does not use a
multi-carrier transmission method. Thus, as shown in FIG. 6, a
change of phase is performed to achieve a period (cycle) of four
and the post-phase change symbols are arranged in the time domain.
As shown in FIG. 12, when multi-carrier transmission, such as OFDM,
is used, then, naturally, precoded post-phase change symbols may be
arranged with respect to the time domain as in FIG. 3, and this
applies to each (sub-)carrier. However, for multi-carrier
transmission, the arrangement may also be in the frequency domain,
or in both the frequency domain and the time domain. The following
describes these arrangements.
[0287] FIGS. 14A and 14B indicate frequency on the horizontal axes
and time on the vertical axes thereof, and illustrate an example of
a symbol reordering method used by the reorderers 1301A and 1301B
from FIG. 13. The frequency axes are made up of (sub-)carriers 0
through 9. The modulated signals z1 and z2 share common timestamps
(timing) and use a common frequency band. FIG. 14A illustrates a
reordering method for the symbols of modulated signal z1, while
FIG. 14B illustrates a reordering method for the symbols of
modulated signal z2. With respect to the symbols of weighted signal
1301A input to serial-to-parallel converter 1302A, the assigned
ordering is #0, #1, #2, #3, and so on. Here, given that the example
deals with a period (cycle) of four, #0, #1, #2, and #3 are
equivalent to one period (cycle). Similarly, #4n, #4n+1, #4n+2, and
#4n+3 (n being a non-zero positive integer) are also equivalent to
one period (cycle).
[0288] As shown in FIG. 14A, symbols #0, #1, #2, #3, and so on are
arranged in order, beginning at carrier 0. Symbols #0 through #9
are given timestamp $1, followed by symbols #10 through #19 which
are given timestamp #2, and so on in a regular arrangement. Here,
modulated signals z1 and z2 are complex signals.
[0289] Similarly, with respect to the symbols of weighted signal
1301B input to serial-to-parallel converter 1302B, the assigned
ordering is #0, #1, #2, #3, and so on. Here, given that the example
deals with a period (cycle) of four, a different change in phase is
applied to each of #0, #1, #2, and #3, which are equivalent to one
period (cycle). Similarly, a different change in phase is applied
to each of #4n, #4n+1, #4n+2, and #4n+3 (n being a non-zero
positive integer), which are also equivalent to one period
(cycle).
[0290] As shown in FIG. 14B, symbols #0, #1, #2, #3, and so on are
arranged in order, beginning at carrier 0. Symbols #0 through #9
are given timestamp $1, followed by symbols #10 through #19 which
are given timestamp $2, and so on in a regular arrangement.
[0291] The symbol group 1402 shown in FIG. 14B corresponds to one
period (cycle) of symbols when the phase changing method of FIG. 6
is used. Symbol #0 is the symbol obtained by using the phase at
timestamp u in FIG. 6, symbol #1 is the symbol obtained by using
the phase at timestamp u+1 in FIG. 6, symbol #2 is the symbol
obtained by using the phase at timestamp u+2 in FIG. 6, and symbol
#3 is the symbol obtained by using the phase at timestamp u+3 in
FIG. 6. Accordingly, for any symbol #x, symbol #x is the symbol
obtained by using the phase at timestamp u in FIG. 6 when x mod 4
equals 0 (i.e., when the remainder of x divided by 4 is 0, mod
being the modulo operator), symbol #x is the symbol obtained by
using the phase at timestamp u+1 in FIG. 6 when x mod 4 equals 1,
symbol #x is the symbol obtained by using the phase at timestamp
u+2 in FIG. 6 when x mod 4 equals 2, and symbol #x is the symbol
obtained by using the phase at timestamp u+3 in FIG. 6 when x mod 4
equals 3.
[0292] In the present Embodiment, modulated signal z1 shown in FIG.
14A has not undergone a change of phase.
[0293] As such, when using a multi-carrier transmission method such
as OFDM, and unlike single carrier transmission, symbols can be
arranged in the frequency domain. Of course, the symbol arrangement
method is not limited to those illustrated by FIGS. 14A and 14B.
Further examples are shown in FIGS. 15A, 15B, 16A, and 16B.
[0294] FIGS. 15A and 15B indicate frequency on the horizontal axes
and time on the vertical axes thereof, and illustrate an example of
a symbol reordering method used by the reorderers 1301A and 1301B
from FIG. 13 that differs from that of FIGS. 14A and 14B. FIG. 15A
illustrates a reordering method for the symbols of modulated signal
z1, while FIG. 15B illustrates a reordering method for the symbols
of modulated signal z2. FIGS. 15A and 15B differ from FIGS. 14A and
14B in the reordering method applied to the symbols of modulated
signal z1 and the symbols of modulated signal z2. In FIG. 15B,
symbols #0 through #5 are arranged at carriers 4 through 9, symbols
#6 though #9 are arranged at carriers 0 through 3, and this
arrangement is repeated for symbols #10 through #19. Here, as in
FIG. 14B, symbol group 1502 shown in FIG. 15B corresponds to one
period (cycle) of symbols when the phase changing method of FIG. 6
is used.
[0295] FIGS. 16A and 16B indicate frequency on the horizontal axes
and time on the vertical axes thereof, and illustrate an example of
a symbol reordering method used by the reorderers 1301A and 1301B
from FIG. 13 that differs from that of FIGS. 14A and 14B. FIG. 16A
illustrates a reordering method for the symbols of modulated signal
z1, while FIG. 16B illustrates a reordering method for the symbols
of modulated signal z2. FIGS. 16A and 16B differ from FIGS. 14A and
14B in that, while FIGS. 14A and 14B showed symbols arranged at
sequential carriers, FIGS. 16A and 16B do not arrange the symbols
at sequential carriers. Obviously, for FIGS. 16A and 16B, different
reordering methods may be applied to the symbols of modulated
signal z1 and to the symbols of modulated signal z2 as in FIGS. 15A
and 15B.
[0296] FIGS. 17A and 17B indicate frequency on the horizontal axes
and time on the vertical axes thereof, and illustrate an example of
a symbol reordering method used by the reorderers 1301A and 1301B
from FIG. 13 that differs from those of FIGS. 14A through 16B. FIG.
17A illustrates a reordering method for the symbols of modulated
signal z1 while FIG. 17B illustrates a reordering method for the
symbols of modulated signal z2. While FIGS. 14A through 16B show
symbols arranged with respect to the frequency axis, FIGS. 17A and
17B use the frequency and time axes together in a single
arrangement.
[0297] While FIG. 6 describes an example where the change of phase
is performed in a four slot period (cycle), the following example
describes an eight slot period (cycle). In FIGS. 17A and 17B, the
symbol group 1702 is equivalent to one period (cycle) of symbols
when the phase changing scheme is used (i.e., to eight symbols)
such that symbol #0 is the symbol obtained by using the phase at
timestamp u, symbol #1 is the symbol obtained by using the phase at
timestamp u+1, symbol #2 is the symbol obtained by using the phase
at timestamp u+2, symbol #3 is the symbol obtained by using the
phase at timestamp u+3, symbol #4 is the symbol obtained by using
the phase at timestamp u+4, symbol #5 is the symbol obtained by
using the phase at timestamp u+5, symbol #6 is the symbol obtained
by using the phase at timestamp u+6, and symbol #7 is the symbol
obtained by using the phase at timestamp u+7. Accordingly, for any
symbol #x, symbol #x is the symbol obtained by using the phase at
timestamp u when x mod 8 equals 0, symbol #x is the symbol obtained
by using the phase at timestamp u+1 when x mod 8 equals 1, symbol
#x is the symbol obtained by using the phase at timestamp u+2 when
x mod 8 equals 2, symbol #x is the symbol obtained by using the
phase at timestamp u+3 when x mod 8 equals 3, symbol #x is the
symbol obtained by using the phase at timestamp u+4 when x mod 8
equals 4, symbol #x is the symbol obtained by using the phase at
timestamp u+5 when x mod 8 equals 5, symbol #x is the symbol
obtained by using the phase at timestamp u+6 when x mod 8 equals 6,
and symbol #x is the symbol obtained by using the phase at
timestamp u+7 when x mod 8 equals 7. In FIGS. 17A and 17B four
slots along the time axis and two slots along the frequency axis
are used for a total of 4.times.2=8 slots, in which one period
(cycle) of symbols is arranged. Here, given m.times.n symbols per
period (cycle) (i.e., m.times.n different phases are available for
multiplication), then n slots (carriers) in the frequency domain
and m slots in the time domain should be used to arrange the
symbols of each period (cycle), such that m>n. This is because
the phase of direct waves fluctuates slowly in the time domain
relative to the frequency domain. Accordingly, the present
Embodiment performs a regular change of phase that reduces the
effect of steady direct waves. Thus, the phase changing period
(cycle) should preferably reduce direct wave fluctuations.
Accordingly, m should be greater than n. Taking the above into
consideration, using the time and frequency domains together for
reordering, as shown in FIGS. 17A and 17B, is preferable to using
either of the frequency domain or the time domain alone due to the
strong probability of the direct waves becoming regular. As a
result, the effects of the present invention are more easily
obtained. However, reordering in the frequency domain may lead to
diversity gain due the fact that frequency-domain fluctuations are
abrupt. As such, using the frequency and time domains together for
reordering is not always ideal.
[0298] FIGS. 18A and 18B indicate frequency on the horizontal axes
and time on the vertical axes thereof, and illustrate an example of
a symbol reordering method used by the reorderers 1301A and 1301B
from FIG. 13 that differs from that of FIGS. 17A and 17B. FIG. 18A
illustrates a reordering method for the symbols of modulated signal
z1, while FIG. 18B illustrates a reordering method for the symbols
of modulated signal z2. Much like FIGS. 17A and 17B, FIGS. 18A and
18B illustrate the use of the time and frequency axes, together.
However, in contrast to FIGS. 17A and 17B, where the frequency axis
is prioritized and the time axis is used for secondary symbol
arrangement, FIGS. 18A and 18B prioritize the rime axis and use the
frequency axis for secondary symbol arrangement. In FIG. 18B,
symbol group 1802 corresponds to one period (cycle) of symbols when
the phase changing method is used.
[0299] In FIGS. 17A, 17B, 18A, and 18B, the reordering method
applied to the symbols of modulated signal z1 and the symbols of
modulated signal z2 may be identical or may differ as like in FIGS.
15A and 15B. Either approach allows good reception quality to be
obtained. Also, in FIGS. 17A, 17B, 18A, and 18B, the symbols may be
arranged non-sequentially as in FIGS. 16A and 16B. Either approach
allows good reception quality to be obtained.
[0300] FIG. 22 indicates frequency on the horizontal axis and time
on the vertical axis thereof, and illustrates an example of a
symbol reordering method used by the reorderers 1301A and 1301B
from FIG. 13 that differs from the above. FIG. 22 illustrates a
regular phase changing method using four slots, similar to
timestamps u through u+3 from FIG. 6. The characteristic feature of
FIG. 22 is that, although the symbols are reordered with respect
the frequency domain, when read along the time axis, a periodic
shift of n (n=1 in the example of FIG. 22) symbols is apparent. The
frequency-domain symbol group 2210 in FIG. 22 indicates four
symbols to which the change of phase is applied at timestamps u
through u+3 from FIG. 6.
[0301] Here, symbol #0 is obtained through a change of phase at
timestamp u, symbol #1 is obtained through a change of phase at
timestamp u+1, symbol #2 is obtained through a change of phase at
timestamp u+2, and symbol #3 is obtained through a change of phase
at timestamp u+3.
[0302] Similarly, for frequency-domain symbol group 2220, symbol #4
is obtained through a change of phase at timestamp u, symbol #5 is
obtained through a change of phase at timestamp u+1, symbol #6 is
obtained through a change of phase at timestamp u+2, and symbol #7
is obtained through a change of phase at timestamp u+3.
[0303] The above-described change of phase is applied to the symbol
at timestamp $1. However, in order to apply periodic shifting with
respect to the time domain, the following change of phases are
applied to symbol groups 2201, 2202, 2203, and 2204.
[0304] For time-domain symbol group 2201, symbol #0 is obtained
through a change of phase at timestamp u, symbol #9 is obtained
through a change of phase at timestamp u+1, symbol #18 is obtained
through a change of phase at timestamp u+2, and symbol #27 is
obtained through a change of phase at timestamp u+3.
[0305] For time-domain symbol group 2202, symbol #28 is obtained
through a change of phase at timestamp u, symbol #1 is obtained
through a change of phase at timestamp u+1, symbol #10 is obtained
through a change of phase at timestamp u+2, and symbol #19 is
obtained through a change of phase at timestamp u+3.
[0306] For time-domain symbol group 2203, symbol #20 is obtained
through a change of phase at timestamp u, symbol #29 is obtained
through a change of phase at timestamp u+1, symbol #2 is obtained
through a change of phase at timestamp u+2, and symbol #11 is
obtained through a change of phase at timestamp u+3.
[0307] For time-domain symbol group 2204, symbol #12 is obtained
through a change of phase at timestamp u, symbol #21 is obtained
through a change of phase at timestamp u+1, symbol #30 is obtained
through a change of phase at timestamp u+2, and symbol #3 is
obtained through a change of phase at timestamp u+3.
[0308] The characteristic feature of FIG. 22 is seen in that,
taking symbol #11 as an example, the two neighbouring symbols
thereof having the same timestamp in the frequency domain (#10 and
#12) are both symbols changed using a different phase than symbol
#11, and the two neighbouring symbols thereof having the same
carrier in the time domain (#2 and #20) are both symbols changed
using a different phase than symbol #11. This holds not only for
symbol #11, but also for any symbol having two neighbouring symbols
in the frequency domain and the time domain. Accordingly, the
change of phase is effectively carried out. This is highly likely
to improve data reception quality as influence from regularizing
direct waves is less prone to reception.
[0309] Although FIG. 22 illustrates an example in which n=1, the
invention is not limited in this manner. The same may be applied to
a case in which n=3. Furthermore, although FIG. 22 illustrates the
realization of the above-described effects by arranging the symbols
in the frequency domain and advancing in the time domain so as to
achieve the characteristic effect of imparting a periodic shift to
the symbol arrangement order, the symbols may also be randomly (or
regularly) arranged to the same effect.
Embodiment 2
[0310] In Embodiment 1, described above, phase changing is applied
to a weighted (precoded with a fixed precoding matrix) signal z(t).
The following Embodiments describe various phase changing methods
by which the effects of Embodiment 1 may be obtained.
[0311] In the above-described Embodiment, as shown in FIGS. 3 and
6, phase changer 317B is configured to perform a change of phase on
only one of the signals output by the weighting unit 600.
[0312] However, phase changing may also be applied before precoding
is performed by the weighting unit 600. In addition to the
components illustrated in FIG. 6, the transmission device may also
feature the weighting unit 600 before the phase changer 317B, as
shown in FIG. 25.
[0313] In such circumstances, the following configuration is
possible. The phase changer 317B performs a regular change of phase
with respect to baseband signal s2(t), on which mapping has been
performed according to a selected modulation method, and outputs
s2'(t)=s2(t)y(t) (where y(t) varies over time t). The weighting
unit 600 executes precoding on s2't, outputs z2(t)=W2s2'(t) (see
Math. 42 (formula 42)) and the result is then transmitted.
[0314] Alternatively, phase changing may be performed on both
modulated signals s1(t) and s2(t). As such, the transmission device
is configured so as to include a phase changer taking both signals
output by the weighting unit 600, as shown in FIG. 26.
[0315] Like phase changer 317B, phase changer 317A performs regular
a regular change of phase on the signal input thereto, and as such
changes the phase of signal z1(t) precoded by the weighting unit.
Post-phase change signal z1(t) is then output to a transmitter.
[0316] However, the phase changing rate applied by the phase
changers 317A and 317B varies simultaneously in order to perform
the phase changing shown in FIG. 26. (The following describes a
non-limiting example of the phase changing method.) For timestamp
u, phase changer 317A from FIG. 26 performs the change of phase
such that z1(t)=y1(t)z1'(t), while phase changer 317B performs the
change of phase such that z2(t)=y2(t)z2'(t). For example, as shown
in FIG. 26, for timestamp u, y.sub.1(u)=e.sup.j0 and
y.sub.2(u)=e.sup.-j.pi./2, for timestamp u+1,
y.sub.1(u+1)=e.sup.j.pi./4 and y.sub.2(u+1)=e.sup.-j3.pi./4, and
for timestamp u+k, y.sub.1(u+k)=.sup.jk.pi./4 and
y.sub.2(u+k)=e.sup.j(k3.pi./4-.pi./2). Here, the regular phase
changing period (cycle) may be the same for both phase changers
317A and 317B, or may vary for each.
[0317] Also, as described above, a change of phase may be performed
before precoding is performed by the weighting unit. In such a
case, the transmission device should be configured as illustrated
in FIG. 27 rather than as illustrated in FIG. 26.
[0318] When a change of phase is carried out on both modulated
signals, each of the transmit signals is, for example, control
information that includes information about the phase changing
pattern. By obtaining the control information, the reception device
knows the phase changing method by which the transmission device
regularly varies the change, i.e., the phase changing pattern, and
is thus able to demodulate (decode) the signals correctly.
[0319] Next, variants of the sample configurations shown in FIGS. 6
and 25 are described with reference to FIGS. 28 and 29. FIG. 28
differs from FIG. 6 in the inclusion of phase change ON/OFF
information 2800 and in that the change of phase is performed on
only one of z1'(t) and z2'(t) (i.e., performed on one of z1'(t) and
z2'(t), which have identical timestamps or a common frequency).
Accordingly, in order to perform the change of phase on one of
z1'(t) and z2'(t), the phase changers 317A and 317B shown in FIG.
28 may each be ON, and performing the change of phase, or OFF, and
not performing the change of phase. The phase change ON/OFF
information 2800 is control information therefor. The phase change
ON/OFF information 2800 is output by the signal processing method
information generator 314 shown in FIG. 3.
[0320] Phase changer 317A of FIG. 28 changes the phase to produce
z1(t)=y.sub.1(t)z1'(t), while phase changer 317B changes the phase
to produce z2(t)=y2(t)z2'(t).
[0321] Here, a change of phase having a period (cycle) of four is,
for example, applied to z1'(t). (Meanwhile, the phase of z2'(t) is
not changed.) Accordingly, for timestamp u, y.sub.1(u)=e.sup.j0 and
y.sub.2(u)=1, for timestamp u+1, y.sub.1(u+1)=e.sup.j.pi./2 and
y.sub.2(u+1)=1, for timestamp u+2, y.sub.1(u+2)=e.sup.j.pi. and
y.sub.2(u+2)=1, and for timestamp u+3, y.sub.1(u+3)=e.sup.j3.pi./2
and y.sub.2(u+3)=1.
[0322] Next, a change of phase having a period (cycle) of four is,
for example, applied to z2'(t). (Meanwhile, the phase of z1'(t) is
not changed.) Accordingly, for timestamp u+4, y.sub.1(u+4)=1 and
y.sub.2(u+4)=e.sup.j0, for timestamp u+5, y.sub.1(u+5)=1 and
y.sub.2(u+5)=e.sup.j.pi./2, for timestamp u+6, y.sub.1(u+6)=1 and
y.sub.2(u+6)=e.sup.j.pi., and for timestamp u+7, y.sub.1(u+7)=1 and
y.sub.2(u+7)=.sub.e.sup.j3.pi./2.
[0323] Accordingly, given the above examples.
[0324] for any timestamp 8k, y.sub.1(8k)=e.sup.j0 and
y.sub.2(8k)=1,
[0325] for any timestamp 8k+1, y.sub.1(8k+1)=e.sup.j.pi./2 and
y.sub.2(8k+1)=1,
[0326] for any timestamp 8k+2, y.sub.1(8k+2)=e.sup.j.pi.and
y.sub.2(8k+2)=1,
[0327] for any timestamp 8k+3, y.sub.1(8k+3)=e.sup.j3.pi./2 and
y.sub.2(8k+3)=1,
[0328] for any timestamp 8k+4, y.sub.1(8k+4)=1 and
y.sub.2(8k+4)=e.sup.j0,
[0329] for any timestamp 8k+5, y.sub.1(8k+3)=1 and
y.sub.2(8k+5)=e.sup.j.pi./2,
[0330] for any timestamp 8k+6, y.sub.1(8k+6)=1 and
y.sub.2(8k+6)=e.sup.j.pi., and
[0331] for any timestamp 8k+7, y.sub.1(8k+7)=1 and
y.sub.2(8k+7)=e.sup.j3.pi./2.
[0332] As described above, there are two intervals, one where the
change of phase is performed on z1'(t) only, and one where the
change of phase is performed on z2'(t) only. Furthermore, the two
intervals form a phase changing period (cycle). While the above
explanation describes the interval where the change of phase is
performed on z1'(t) only and the interval where the change of phase
is performed on z2'(t) only as being equal, no limitation is
intended in this manner. The two intervals may also differ. In
addition, while the above explanation describes performing a change
of phase having a period (cycle) of four on z1'(t) only and then
performing a change of phase having a period (cycle) of four on
z2'(t) only, no limitation is intended in this manner. The changes
of phase may be performed on z1'(t) and on z2'(t) in any order
(e.g., the change of phase may alternate between being performed on
z1'(t) and on z2'(t), or may be performed in random order). Phase
changer 317A of FIG. 29 changes the phase to produce
s1=y.sub.1(t)s1(t), while phase changer 317B changes the phase to
produce s2'(t)=y2(t)s2(t).
[0333] Here, a change of phase having a period (cycle) of four is,
for example, applied to s1(t). (Meanwhile, s2(t) remains
unchanged). Accordingly, for timestamp u, y.sub.1(u)=e.sup.j0 and
y.sub.2(u)=1, for timestamp u+1, y.sub.1(u+1)=e.sup.j.pi./2 and
y.sub.2(u+1)=1, for timestamp u+2, y.sub.1(u+2)=e.sup.j.pi. and
y.sub.2(u+2)=1, and for timestamp u+3, y.sub.1(u+3)=e.sup.j3.pi./2
and y.sub.2(u+3)=1.
[0334] Next, a change of phase having a period (cycle) of four is,
for example, applied to s2(t). (Meanwhile, s1(t) remains
unchanged). Accordingly, for timestamp u+4, y.sub.1(u+4)=1 and
y.sub.2(u+4)=e.sup.j0, for timestamp u+5, y.sub.1(u+5)=1 and
y.sub.2(u+5)=e.sup.j.pi./2, for timestamp u+6, y.sub.1(u+6)=1 and
y.sub.2(u+6)=e.sup.j.pi., and for timestamp u+7, y.sub.1(u+7)=1 and
y.sub.2(u+7)=e.sup.j3.pi./2.
[0335] Accordingly, given the above examples,
[0336] for any timestamp 8k, y.sub.1(8k)=e.sup.j0 and
y.sub.2(8k)=1,
[0337] for any timestamp 8k+1, y.sub.1(8k+1)=e.sup.j.pi./2 and
y.sub.2(8k+1)=1,
[0338] for any timestamp 8k+2, y.sub.1(8k+2)=e.sup.j.pi. and
y.sub.2(8k+2)=1,
[0339] for any timestamp 8k+3, y.sub.1(8k+3)=e.sup.j3.pi./2 and
y.sub.2(8k+3)=1,
[0340] for any timestamp 8k+4, y.sub.1(8k+4)=1 and
y.sub.2(8k+4)=e.sup.j0,
[0341] for any timestamp 8k+5, y.sub.1(8k+5)=1 and
y.sub.2(8k+5)=e.sup.j.pi./2,
[0342] for any timestamp 8k+6, y.sub.i(8k+6)=1 and
y.sub.2(8k+6)=e.sup.j.pi., and
[0343] for any timestamp 8k+7, y.sub.1(8k+7)=1 and
y.sub.2(8k+7)=e.sup.j3.pi./2.
[0344] As described above, there are two intervals, one where the
change of phase is performed on s1(t) only, and one where the
change of phase is performed on s2(t) only. Furthermore, the two
intervals form a phase changing period (cycle). Although the above
explanation describes the interval where the change of phase is
performed on s1(t) only and the interval where the change of phase
is performed on s2(t) only as being equal, no limitation is
intended in this manner. The two intervals may also differ. In
addition, while the above explanation describes performing the
change of phase having a period (cycle) of four on s1(t) only and
then performing the change of phase having a period (cycle) of four
on s2(t) only, no limitation is intended in this manner. The
changes of phase may be performed on s1(t) and on s2(t) in any
order (e.g., may alternate between being performed on s1(t) and on
s2(t), or may be performed in random order).
[0345] Accordingly, the reception conditions under which the
reception device receives each transmit signal z1(t) and z2(t) are
equalized. By periodically switching the phase of the symbols in
the received signals z1(t) and z2(t), the ability of the error
corrected codes to correct errors may be improved, thus
ameliorating received signal quality in the LOS environment.
[0346] Accordingly, Embodiment 2 as described above is able to
produce the same results as the previously described Embodiment
1.
[0347] Although the present Embodiment used a single-carrier
method, i.e., time domain phase changing, as an example, no
limitation is intended in this regard. The same effects are also
achievable using multi-carrier transmission. Accordingly, the
present Embodiment may also be realized using, for example,
spread-spectrum communications, OFDM, SC-FDMA (Single Carrier
Frequency-Division Multiple Access), SC-OFDM, wavelet OFDM as
described in Non-Patent Literature 7, and so on. As previously
described, while the present Embodiment explains the change of
phase as changing the phase with respect to the time domain t, the
phase may alternatively be changed with respect to the frequency
domain as described in Embodiment 1. That is, considering the phase
changing method in the time domain t described in the present
Embodiment and replacing t with f (f being the ((sub-) carrier)
frequency) leads to a change of phase applicable to the frequency
domain. Also, as explained above for Embodiment 1, the phase
changing method of the present Embodiment is also applicable to a
change of phase with respect to both the time domain and the
frequency domain.
[0348] Accordingly, although FIGS. 6, 25, 26, and 27 illustrate
changes of phase in the time domain, replacing time t with carrier
f in each of FIGS. 6, 25, 26, and 27 corresponds to a change of
phase in the frequency domain. In other words, replacing (t) with
(t, f) where t is time and f is frequency corresponds to performing
the change of phase on time-frequency blocks.
[0349] Furthermore, in the present Embodiment, symbols other than
data symbols, such as pilot symbols (preamble, unique word, etc) or
symbols transmitting control information, may be arranged within
the frame in any manner.
Embodiment 3
[0350] Embodiments 1 and 2, described above, discuss regular
changes of phase. Embodiment 3 describes a method of allowing the
reception device to obtain good received signal quality for data,
regardless of the reception device arrangement, by considering the
location of the reception device with respect to the transmission
device.
[0351] Embodiment 3 concerns the symbol arrangement within signals
obtained through a change of phase.
[0352] FIG. 31 illustrates an example of frame configuration for a
portion of the symbols within a signal in the time-frequency
domains, given a transmission method where a regular change of
phase is performed for a multi-carrier method such as OFDM.
[0353] First, an example is explained in which the change of phase
is performed one of two baseband signals, precoded as explained in
Embodiment 1 (see FIG. 6).
[0354] (Although FIG. 6 illustrates a change of phase in the time
domain, switching time t with carrier f in FIG. 6 corresponds to a
change of phase in the frequency domain. In other words, replacing
(t) with (t, f) where t is time and f is frequency corresponds to
performing phase changes on time-frequency blocks.)
[0355] FIG. 31 illustrates the frame configuration of modulated
signal z2', which is input to phase changer 317B from FIG. 12. Each
square represents one symbol (although both signals s1 and s2 are
included for precoding purposes, depending on the precoding matrix,
only one of signals s1 and s2 may be used).
[0356] Consider symbol 3100 at carrier 2 and timestamp $2 of FIG.
31. The carrier here described may alternatively be termed a
sub-carrier.
[0357] Within carrier 2, there is a very strong correlation between
the channel conditions for symbol 3100A at carrier 2, timestamp $2
and the channel conditions for the time domain nearest-neighbour
symbols to timestamp $2, i.e., symbol 3013 at timestamp $1 and
symbol 3101 at timestamp $3 within carrier 2.
[0358] Similarly, for timestamp $2, there is a very strong
correlation between the channel conditions for symbol 3100 at
carrier 2, timestamp $2 and the channel conditions for the
frequency-domain nearest-neighbour symbols to carrier 2, i.e.,
symbol 3104 at carrier 1, timestamp $2 and symbol 3104 at timestamp
$2, carrier 3.
[0359] As described above, there is a very strong correlation
between the channel conditions for symbol 3100 and the channel
conditions for each symbol 3101, 3102, 3103, and 3104.
[0360] The present description considers N different phases (N
being an integer, N>2) for multiplication in a transmission
method where the phase is regularly changed. The symbols
illustrated in FIG. 31 are indicated as e.sup.j0, for example. This
signifies that this symbol is signal z2' from FIG. 6 having
undergone a change in phase through multiplication by e.sup.j0.
That is, the values indicated in FIG. 31 for each of the symbols
are the values of y(t) from Math. 42 (formula 42), which are also
the values of z2(t)=y2(t)z2'(t) described in Embodiment 2.
[0361] The present Embodiment takes advantage of the high
correlation in channel conditions existing between neighbouring
symbols in the frequency domain and/or neighbouring symbols in the
time domain in a symbol arrangement enabling high data reception
quality to be obtained by the reception device receiving the
phase-changed symbols.
[0362] In order to achieve this high data reception quality,
conditions #1 and #2 are necessary.
(Condition #1)
[0363] As shown in FIG. 6, for a transmission method involving a
regular change of phase performed on precoded baseband signal z2'
using multi-carrier transmission such as OFDM, time X, carrier Y
must be a symbol for transmitting data (hereinafter, data symbol),
neighbouring symbols in the time domain, i.e., at time X-1, carrier
Y and at time X+1, carrier Y must also be data symbols, and a
different change of phase must be performed on precoded baseband
signal z2' corresponding to each of these three data symbols, i.e.,
on precoded baseband signal z2' at time X, carrier Y, at time X-1,
carrier Y and at time X+1, carrier Y.
(Condition #2)
[0364] As shown in FIG. 6, for a transmission method involving a
regular change of phase performed on precoded baseband signal z2'
using multi-carrier transmission such as OFDM, time X, carrier Y
must be a data symbol, neighbouring symbols in the frequency
domain, i.e., at time X, carrier Y-1 and at time X, carrier Y+1
must also be data symbols, and a different change of phase must be
performed on precoded baseband signal z2' corresponding to each of
these three data symbols, i.e., on precoded baseband signal z2' at
time X, carrier Y, at time X, carrier Y-1 and at time X, carrier
Y+1.
[0365] Ideally, data symbols satisfying Condition #1 should be
present. Similarly, data symbols satisfying Condition #2 should be
present.
[0366] The reasons supporting Conditions #1 and #2 are as
follows.
[0367] A very strong correlation exists between the channel
conditions of given symbol of a transmit signal (hereinafter,
symbol A) and the channel conditions of the symbols neighbouring
symbol A in the time domain, as described above.
[0368] Accordingly, when three neighbouring symbols in the time
domain each have different phases, then despite reception quality
degradation in the LOS environment (poor signal quality caused by
degradation in conditions due to phase relations despite high
signal quality in terms of SNR) for symbol A, the two remaining
symbols neighbouring symbol A are highly likely to provide good
reception quality. As a result, good received signal quality is
achievable after error correction and decoding.
[0369] Similarly, a very strong correlation exists between the
channel conditions of given symbol of a transmit signal
(hereinafter, symbol A) and the channel conditions of the symbols
neighbouring symbol A in the frequency domain, as described
above.
[0370] Accordingly, when three neighbouring symbols in the
frequency domain each have different phases, then despite reception
quality degradation in the LOS environment (poor signal quality
caused by degradation in conditions due to direct wave phase
relationships despite high signal quality in terms of SNR) for
symbol A, the two remaining symbols neighbouring symbol A are
highly likely to provide good reception quality. As a result, good
received signal quality is achievable after error correction and
decoding.
[0371] Combining Conditions #1 and #2, ever greater data reception
quality is likely achievable for the reception device. Accordingly,
the following Condition #3 can be derived.
(Condition #3)
[0372] As shown in FIG. 6, for a transmission method involving a
regular change of phase performed on precoded baseband signal z2'
using multi-carrier transmission such as OFDM, time X, carrier Y
must be a data symbol, neighbouring symbols in the time domain,
i.e., at time X-1, carrier Y and at time X+1, carrier Y must also
be data symbols, and neighbouring symbols in the frequency domain,
i.e., at time X, carrier Y-1 and at time X, carrier Y+1 must also
be data symbols, and a different change in phase must be performed
on precoded baseband signal z2' corresponding to each of these five
data symbols, i.e., on precoded baseband signal z2' at time X,
carrier Y, at time X, carrier Y-1, at time X, carrier Y+1, at a
time X-1, carrier Y, and at time X+1, carrier Y.
[0373] Here, the different changes in phase are as follows. Phase
changes are defined from 0 radians to 2.pi. radians. For example,
for time X, carrier Y, a phase change of e.sup.j.theta.X,Y is
applied to precoded baseband signal z2' from FIG. 6, for time X-1,
carrier Y, a phase change of e.sup.j.theta.X-1,Y is applied to
precoded baseband signal z2' from FIG. 6, for time X+1, carrier Y,
a phase change of e.sup.j.theta.X+1,Y is applied to precoded
baseband signal z2' from FIG. 6, such that
0.ltoreq..theta..sub.X,Y<2.pi.,
0.ltoreq..theta..sub.X-1,Y<2.pi., and
0.ltoreq..theta..sub.X+1,Y2.pi., all units being in radians.
Accordingly, for Condition #1, it follows that
.theta..sub.X,Y.noteq..theta..sub.X-1,Y,
.theta..sub.X,Y.noteq..theta..sub.X+1,Y, and that
.theta..sub.X-1,Y.noteq..theta..sub.X+1,Y. Similarly, for Condition
#2, it follows that .theta..sub.X,Y.noteq..theta..sub.X,Y-1,
.theta..sub.X,Y.noteq..theta..sub.S,Y+1, and that
.theta..sub.X,Y-1.noteq..theta..sub.S,Y+1. And, for Condition #3,
it follows that .theta..sub.X,Y.noteq..theta..sub.X-1,Y,
.theta..sub.X,Y.noteq..theta..sub.X+1,Y,
.theta..sub.X,Y.noteq..theta..sub.X,Y-1,
.theta..sub.X,Y.noteq..theta..sub.X,Y-1,
.theta..sub.X-1,Y.noteq..theta..sub.X+1,Y,
.theta..sub.X-1,Y.noteq..theta..sub.X,Y-1,
.theta..sub.X-1,Y.noteq..theta..sub.X+1,Y,
.theta..sub.X+1,Y.noteq..theta..sub.X-1,Y,
.theta..sub.X+1,Y.noteq..theta..sub.X,Y+1, and
.theta..sub.X,Y-1.noteq..theta..sub.X,Y+1.
[0374] Ideally, data symbols satisfying Condition #3 should be
present.
[0375] FIG. 31 illustrates an example of Condition #3 where symbol
A corresponds to symbol 3100. The symbols are arranged such that
the phase by which precoded baseband signal z2' from FIG. 6 is
multiplied differs for symbol 3100, for both neighbouring symbols
thereof in the time domain 3101 and 3102, and for both neighbouring
symbols thereof in the frequency domain 3102 and 3104. Accordingly,
despite received signal quality degradation of symbol 3100 for the
receiver, good signal quality is highly likely for the neighbouring
signals, thus guaranteeing good signal quality after error
correction.
[0376] FIG. 32 illustrates a symbol arrangement obtained through
phase changes under these conditions.
[0377] As evident from FIG. 32, with respect to any data symbol, a
different change in phase is applied to each neighbouring symbol in
the time domain and in the frequency domain. As such, the ability
of the reception device to correct errors may be improved.
[0378] In other words, in FIG. 32, when all neighbouring symbols in
the time domain are data symbols, Condition #1 is satisfied for all
Xs and all Ys.
[0379] Similarly, in FIG. 32, when all neighbouring symbols in the
frequency domain are data symbols, Condition #2 is satisfied for
all Xs and all Ys.
[0380] Similarly, in FIG. 32, when all neighbouring symbols in the
frequency domain are data symbols and all neighbouring symbols in
the time domain are data symbols, Condition #3 is satisfied for all
Xs and all Ys.
[0381] The following describes an example in which a change of
phase is performed on two precoded baseband signals, as explained
in Embodiment 2 (see FIG. 26).
[0382] When a change of phase is performed on precoded baseband
signal z1' and precoded baseband signal z2' as shown in FIG. 26,
several phase changing methods are possible. The details thereof
are explained below.
[0383] Scheme 1 involves a change in phase of precoded baseband
signal z2' as described above, to achieve the change in phase
illustrated by FIG. 32. In FIG. 32, a change of phase having a
period (cycle) of ten is applied to precoded baseband signal z2'.
However, as described above, in order to satisfy Conditions #1, #2,
and #3, the change in phase applied to precoded baseband signal z2'
at each (sub-)carrier varies over time. (Although such changes are
applied in FIG. 32 with a period (cycle) of ten, other phase
changing methods are also possible.) Then, as shown in FIG. 33, the
change in phase performed on precoded baseband signal z1' produces
a constant value that is one-tenth of that of the change in phase
performed on precoded baseband signal z2'. In FIG. 33, for a period
(cycle) (of change in phase performed on precoded baseband signal
z2') including timestamp $1, the value of the change in phase
performed on precoded baseband signal z1' is e. Then, for the next
period (cycle) (of change in phase performed on precoded baseband
signal z2') including timestamp $2, the value of the change in
phase performed on precoded baseband signal z1' is e.sup.j.pi./9,
and so on.
[0384] The symbols illustrated in FIG. 33 are indicated as
e.sup.j0, for example. This signifies that this symbol is signal
z1' from FIG. 26 to which a change in phase has been applied
through multiplication by e.sup.j0. That is, the values indicated
in FIG. 33 for each of the symbols are the values of
z1(t)=y.sub.1(t)z1'(t) described in Embodiment 2 for
y.sub.1(t).
[0385] As shown in FIG. 33, the change in phase performed on
precoded baseband signal z1' produces a constant value that is
one-tenth that of the change in phase performed on precoded
baseband signal z2' such that the post-phase change value varies
with the number of each period (cycle). (As described above, in
FIG. 33, the value is e.sup.j0 for the first period (cycle),
e.sup.j.pi./9 for the second period (cycle), and so on.)
[0386] As described above, the change in phase performed on
precoded baseband signal z2' has a period (cycle) of ten, but the
period (cycle) can be effectively made greater than ten by taking
the change in phase applied to precoded baseband signal z1' and to
precoded baseband signal z2' into consideration. Accordingly, data
reception quality may be improved for the reception device.
[0387] Scheme 2 involves a change in phase of precoded baseband
signal z2' as described above, to achieve the change in phase
illustrated by FIG. 32. In FIG. 32, a change of phase having a
period (cycle) of ten is applied to precoded baseband signal z2'.
However, as described above, in order to satisfy Conditions #1, #2,
and #3, the change in phase applied to precoded baseband signal z2'
at each (sub-)carrier varies over time. (Although such changes are
applied in FIG. 32 with a period (cycle) of ten, other phase
changing methods are also possible.) Then, as shown in FIG. 30, the
change in phase performed on precoded baseband signal z1' differs
from that performed on precoded baseband signal z2' in having a
period (cycle) of three rather than ten.
[0388] The symbols illustrated in FIG. 30 are indicated as
e.sup.j0, for example. This signifies that this symbol is signal
z1' from FIG. 26 to which a change in phase has been applied
through multiplication by e.sup.j0. That is, the values indicated
in FIG. 30 for each of the symbols are the values of
z1(t)=y.sub.1(t)z1'(t) described in Embodiment 2 for
y.sub.1(t).
[0389] As described above, the change in phase performed on
precoded baseband signal z2' has a period (cycle) of ten, but by
taking the changes in phase applied to precoded baseband signal z1'
and precoded baseband signal z2' into consideration, the period
(cycle) can be effectively made equivalent to 30 for both precoded
baseband signals z1' and z2'. Accordingly, data reception quality
may be improved for the reception device. An effective way of
applying method 2 is to perform a change in phase on precoded
baseband signal z1' with a period (cycle) of N and perform a change
in phase on precoded baseband signal z2' with a period (cycle) of M
such that N and M are coprime. As such, by taking both precoded
baseband signals z1' and z2' into consideration, a period (cycle)
of N.times.M is easily achievable, effectively making the period
(cycle) greater when N and M are coprime.
[0390] The above describes an example of the phase changing method
pertaining to Embodiment 3. The present invention is not limited in
this manner. As explained for Embodiments 1 and 2, a change in
phase may be performed with respect the frequency domain or the
time domain, or on time-frequency blocks. Similar improvement to
the data reception quality can be obtained for the reception device
in all cases.
[0391] The same also applies to frames having a configuration other
than that described above, where pilot symbols (SP symbols) and
symbols transmitting control information are inserted among the
data symbols. The details of the change in phase in such
circumstances are as follows.
[0392] FIGS. 47A and 47B illustrate the frame configuration of
modulated signals (precoded baseband signals) z1 or z1' and z2' in
the time-frequency domain. FIG. 47A illustrates the frame
configuration of modulated signal (precoded baseband signal) z1 or
z1' while FIG. 47B illustrates the frame configuration of modulated
signal (precoded baseband signal) z2'. In FIGS. 47A and 47B, 4701
marks pilot symbols while 4702 marks data symbols. The data symbols
4702 are symbols on which precoding or precoding and a change in
phase have been performed.
[0393] FIGS. 47A and 47B, like FIG. 6, indicate the arrangement of
symbols when a change in phase is applied to precoded baseband
signal z2' (while no change of phase is performed on precoded
baseband signal z1). (Although FIG. 6 illustrates a change in phase
with respect to the time domain, switching time t with carrier fin
FIG. 6 corresponds to a change in phase with respect to the
frequency domain. In other words, replacing (t) with (t, f) where t
is time and f is frequency corresponds to performing a change of
phase on time-frequency blocks.) Accordingly, the numerical values
indicated in FIGS. 47A and 47B for each of the symbols are the
values of precoded baseband signal z2' after a change of phase is
performed. No values are given for the symbols of precoded baseband
signal z1' (z1) as no change of phase is performed thereon.
[0394] The key point of FIGS. 47A and 47B is that a change of phase
is performed on the data symbols of precoded baseband signal z2',
i.e., on precoded symbols. (The symbols under discussion, being
precoded, actually include both symbols s1 and s2.) Accordingly, no
change in phase is performed on the pilot symbols inserted in
z2'.
[0395] FIGS. 48A and 48B illustrate the frame configuration of
modulated signals (precoded baseband signals) z1 or z1' and z2' in
the time-frequency domain. FIG. 48A illustrates the frame
configuration of modulated signal (precoded baseband signal) z1 or
z1' while FIG. 48B illustrates the frame configuration of modulated
signal (precoded baseband signal) z2'. In FIGS. 48A and 48B, 4701
marks pilot symbols while 4702 marks data symbols. The data symbols
4702 are symbols on which precoding or precoding and a change in
phase have been performed.
[0396] FIGS. 48A and 48B, like FIG. 26, indicate the arrangement of
symbols when a change of phase is applied to precoded baseband
signal z1' and to precoded baseband signal z2'. (Although FIG. 26
illustrates a change in phase with respect to the time domain,
switching time t with carrier f in FIG. 26 corresponds to a change
in phase with respect to the frequency domain. In other words,
replacing (t) with (t, f) where t is time and f is frequency
corresponds to performing a change of phase on time-frequency
blocks.) Accordingly, the numerical values indicated in FIGS. 48A
and 48B for each of the symbols are the values of precoded baseband
signal z1' and z2' after a change of phase.
[0397] The key point of FIGS. 48A and 48B is that a change of phase
is performed on the data symbols of precoded baseband signal z1',
that is, on the precoded symbols thereof, and on the data symbols
of precoded baseband signal z2', that is, on the precoded symbols
thereof. (The symbols under discussion, being precoded, actually
include both symbols s1 and s2.) Accordingly, no change in phase is
performed on the pilot symbols inserted in z1', nor on the pilot
symbols inserted in z2'.
[0398] FIGS. 49A and 49B illustrate the frame configuration of
modulated signals (precoded baseband signals) z1 or z1' and z2' in
the time-frequency domain. FIG. 49A illustrates the frame
configuration of modulated signal (precoded baseband signal) z1 or
z1' while FIG. 49B illustrates the frame configuration of modulated
signal (precoded baseband signal) z2'. In FIGS. 49A and 49B, 4701
marks pilot symbols, 4702 marks data symbols, and 4901 marks null
symbols for which the in-phase component of the baseband signal I=0
and the quadrature component Q=0. As such, data symbols 4702 are
symbols on which precoding or precoding and a change in phase have
been performed. FIGS. 49A and 49B differ from FIGS. 47A and 47B in
the configuration method for symbols other than data symbols. The
times and carriers at which pilot symbols are inserted into
modulated signal z1' are null symbols in modulated signal z2'.
Conversely, the times and carriers at which pilot symbols are
inserted into modulated signal z2' are null symbols in modulated
signal z1'.
[0399] FIGS. 49A and 49B, like FIG. 6, indicate the arrangement of
symbols when a change in phase is applied to precoded baseband
signal z2' (while no change of phase is performed on precoded
baseband signal z1). (Although FIG. 6 illustrates a change in phase
with respect to the time domain, switching time t with carrier fin
FIG. 6 corresponds to a change in phase with respect to the
frequency domain. In other words, replacing (t) with (t, f) where t
is time and f is frequency corresponds to performing a change of
phase on time-frequency blocks.) Accordingly, the numerical values
indicated in FIGS. 49A and 49B for each of the symbols are the
values of precoded baseband signal z2' after a change of phase is
performed. No values are given for the symbols of precoded baseband
signal z1' (z1) as no change of phase is performed thereon.
[0400] The key point of FIGS. 49A and 49B is that a change of phase
is performed on the data symbols of precoded baseband signal z2',
i.e., on precoded symbols. (The symbols under discussion, being
precoded, actually include both symbols s1 and s2.) Accordingly, no
change in phase is performed on the pilot symbols inserted in
z2'.
[0401] FIGS. 50A and 50B illustrate the frame configuration of
modulated signals (precoded baseband signals) z1 or z1' and z2' in
the time-frequency domain. FIG. 50A illustrates the frame
configuration of modulated signal (precoded baseband signal) z1 or
z1' while FIG. 50B illustrates the frame configuration of modulated
signal (precoded baseband signal) z2'. In FIGS. 50A and 50B, 4701
marks pilot symbols, 4702 marks data symbols, and 4901 marks null
symbols for which the in-phase component of the baseband signal I=0
and the quadrature component Q=0. As such, data symbols 4702 are
symbols on which precoding or precoding and a change in phase have
been performed. FIGS. 50A and 50B differ from FIGS. 48A and 48B in
the configuration method for symbols other than data symbols. The
times and carriers at which pilot symbols are inserted into
modulated signal z1' are null symbols in modulated signal z2'.
Conversely, the times and carriers at which pilot symbols are
inserted into modulated signal z2' are null symbols in modulated
signal z1'.
[0402] FIGS. 50A and 50B, like FIG. 26, indicate the arrangement of
symbols when a change of phase is applied to precoded baseband
signal z1' and to precoded baseband signal z2'. (Although FIG. 26
illustrates a change in phase with respect to the time domain,
switching time t with carrier f in FIG. 26 corresponds to a change
in phase with respect to the frequency domain. In other words,
replacing (t) with (t, f) where t is time and f is frequency
corresponds to performing a change of phase on time-frequency
blocks.) Accordingly, the numerical values indicated in FIGS. 50A
and 50B for each of the symbols are the values of precoded baseband
signal z1' and z2' after the change in phase.
[0403] The key point of FIGS. 50A and 50B is that a change of phase
is performed on the data symbols of precoded baseband signal z1',
that is, on the precoded symbols thereof, and on the data symbols
of precoded baseband signal z2', that is, on the precoded symbols
thereof. (The symbols under discussion, being precoded, actually
include both symbols s1 and s2.) Accordingly, no change in phase is
performed on the pilot symbols inserted in z1', nor on the pilot
symbols inserted in z2'.
[0404] FIG. 51 illustrates a sample configuration of a transmission
device generating and transmitting modulated signal having the
frame configuration of FIGS. 47A, 47B, 49A, and 49B. Components
thereof performing the same operations as those of FIG. 4 use the
same reference symbols thereas.
[0405] In FIG. 51, the weighting units 308A and 308B and phase
changer 317B only operate at times indicated by the frame
configuration signal 313 as corresponding to data symbols.
[0406] In FIG. 51, a pilot symbol generator 5101 (that also
generates null symbols) outputs baseband signals 5102A and 5102B
for a pilot symbol whenever the frame configuration signal 313
indicates a pilot symbol (and a null symbol).
[0407] Although not indicated in the frame configurations from
FIGS. 47A through 50B, when precoding (or phase rotation) is not
performed, such as when transmitting a modulated signal using only
one antenna (such that the other antenna transmits no signal) or
when using a space-time coding transmission method (particularly,
space-time block coding) to transmit control information symbols,
then the frame configuration signal 313 takes control information
symbols 5104 and control information 5103 as input. When the frame
configuration signal 313 indicates a control information symbol,
baseband signals 5102A and 5102B thereof are output.
[0408] Wireless units 310A and 310B of FIG. 51 take a plurality of
baseband signals as input and select a desired baseband signal
according to the frame configuration signal 313. The wireless units
310A and 310B then apply OFDM signal processing and output
modulated signals 311A and 311B conforming to the frame
configuration.
[0409] FIG. 52 illustrates a sample configuration of a transmission
device generating and transmitting modulated signal having the
frame configuration of FIGS. 48A, 48B, 50A, and 50B. Components
thereof performing the same operations as those of FIGS. 4 and 51
use the same reference symbols thereas. FIG. 51 features an
additional phase changer 317A that only operates when the frame
configuration signal 313 indicates a data symbol. At all other
times, the operations are identical to those explained for FIG.
51.
[0410] FIG. 53 illustrates a sample configuration of a transmission
device that differs from that of FIG. 51. The following describes
the points of difference. As shown in FIG. 53, phase changer 317B
takes a plurality of baseband signals as input. Then, when the
frame configuration signal 313 indicates a data symbol, phase
changer 317B performs the change in phase on precoded baseband
signal 316B. When frame configuration signal 313 indicates a pilot
symbol (or null symbol) or a control information symbol, phase
changer 317B pauses phase changing operations such that the symbols
of the baseband signal are output as-is. (This may be interpreted
as performing forced rotation corresponding to e.sup.j0.)
[0411] A selector 5301 takes the plurality of baseband signals as
input and selects a baseband signal having a symbol indicated by
the frame configuration signal 313 for output.
[0412] FIG. 54 illustrates a sample configuration of a transmission
device that differs from that of FIG. 52. The following describes
the points of difference. As shown in FIG. 54, phase changer 317B
takes a plurality of baseband signals as input. Then, when the
frame configuration signal 313 indicates a data symbol, phase
changer 317B performs the change in phase on precoded baseband
signal 316B. When frame configuration signal 313 indicates a pilot
symbol (or null symbol) or a control information symbol, phase
changer 317B pauses phase changing operations such that the symbols
of the baseband signal are output as-is. (This may be interpreted
as performing forced rotation corresponding to e.sup.j0)
[0413] Similarly, as shown in FIG. 54, phase changer 5201 takes a
plurality of baseband signals as input. Then, when the frame
configuration signal 313 indicates a data symbol, phase changer
5201 performs the change in phase on precoded baseband signal 309A.
When frame configuration signal 313 indicates a pilot symbol (or
null symbol) or a control information symbol, phase changer 5201
pauses phase changing operations such that the symbols of the
baseband signal are output as-is. (This may be interpreted as
performing forced rotation corresponding to e.sup.j0.)
[0414] The above explanations are given using pilot symbols,
control symbols, and data symbols as examples. However, the present
invention is not limited in this manner. When symbols are
transmitted using methods other than precoding, such as
single-antenna transmission or transmission using space-time block
coding, not performing a change of phase is important. Conversely,
performing a change of phase on symbols that have been precoded is
the key point of the present invention.
[0415] Accordingly, a characteristic feature of the present
invention is that the change of phase is not performed on all
symbols within the frame configuration in the time-frequency
domain, but only performed on signals that have been precoded.
Embodiment 4
[0416] Embodiments 1 and 2, described above, discuss a regular
change of phase. Embodiment 3, however, discloses performing a
different change of phase on neighbouring symbols.
[0417] The present Embodiment describes a phase changing method
that varies according to the modulation method and the encoding
rate of the error-correcting codes used by the transmission
device.
[0418] Table 1, below, is a list of phase changing method settings
corresponding to the settings and parameters of the transmission
device.
TABLE-US-00001 TABLE 1 No. of Modulated Phase Transmission Changing
Signals Modulation Scheme Coding Rate Pattern 2 #1: QPSK, #2: QPSK
#1: 1/2, #2 2/3 #1: --, #2: A 2 #1: QPSK, #2: QPSK #1: 1/2, #2: 3/4
#1: A, #2: B 2 #1: QPSK, #2: QPSK #1: 2/3, #2: 3/5 #1: A, #2: C 2
#1: QPSK, #2: QPSK #1: 2/3, #2: 2/3 #1: C, #2: -- 2 #1: QPSK, #2:
QPSK #1: 3/3, #2: 5/6 #1: D, #2: E 2 #1: QPSK, #2: 16-QAM #1: 1/2,
#2: 2/3 #1: B, #2: A 2 #1: QPSK, #2: 16-QAM #1: 1/2, #2: 3/4 #1: A,
#2: C 2 #1: QPSK, #2: 16-QAM #1: 1/2, #2: 3/5 #1: --, #2: E 2 #1:
QPSK, #2: 16-QAM #1: 2/3, #2: 3/4 #1: D, #2: -- 2 #1: QPSK, #2:
16-QAM #1: 2/3, #2: 5/6 #1: D, #2: B 2 #1: 16-QAM, #2: #1: 1/2, #2:
2/3 #1: --, #2: E 16-QAM . . . . . . . . . . . .
[0419] In Table 1, #1 denotes modulated signal s1 from Embodiment 1
described above (baseband signal s1 modulated with the modulation
method set by the transmission device) and #2 denotes modulated
signal s2 (baseband signal s2 modulated with the modulation method
set by the transmission device). The encoding rate column of Table
1 indicates the encoding rate of the error-correcting codes for
modulation methods #1 and #2. The phase changing pattern column of
Table 1 indicates the phase changing method applied to precoded
baseband signals z1 (z1') and z2 (z2'), as explained in Embodiments
1 through 3. Although the phase changing patterns are labeled A, B,
C, D, E, and so on, this refers to the phase change degree applied,
for example, in a phase changing pattern given by Math. 46 (formula
46) and Math. 47 (formula 47), above. In the phase changing pattern
column of Table 1, the dash signifies that no change of phase is
applied.
[0420] The combinations of modulation method and encoding rate
listed in Table 1 are examples. Other modulation methods (such as
128-QAM and 256-QAM) and encoding rates (such as 7/8) not listed in
Table 1 may also be included. Also, as described in Embodiment 1,
the error-correcting codes used for s1 and s2 may differ (Table 1
is given for cases where a single type of error-correcting codes is
used, as in FIG. 4). Furthermore, the same modulation method and
encoding rate may be used with different phase changing patterns.
The transmission device transmits information indicating the phase
changing patterns to the reception device. The reception device
specifies the phase changing pattern by cross-referencing the
information and Table 1, then performs demodulation and decoding.
When the modulation method and error-correction method determine a
unique phase changing pattern, then as long as the transmission
device transmits the modulation method and information regarding
the error-correction method, the reception device knows the phase
changing pattern by obtaining that information. As such,
information pertaining to the phase changing pattern is not
strictly necessary.
[0421] In Embodiments 1 through 3, the change of phase is applied
to precoded baseband signals. However, the amplitude may also be
modified along with the phase in order to apply periodical, regular
changes. Accordingly, an amplification modification pattern
regularly modifying the amplitude of the modulated signals may also
be made to conform to Table 1. In such circumstances, the
transmission device should include an amplification modifier that
modifies the amplification after weighting unit 308A or weighting
unit 308B from FIG. 3 or 4. In addition, amplification modification
may be performed on only one of or on both of the precoded baseband
signals z1(t) and z2(t) (in the former case, the amplification
modifier is only needed after one of weighting unit 308A and
308B).
[0422] Furthermore, although not indicated in Table 1 above, the
mapping scheme may also be regularly modified by the mapper,
without a regular change of phase.
[0423] That is, when the mapping method for modulated signal s1(t)
is 16-QAM and the mapping method for modulated signal s2(t) is also
16-QAM, the mapping method applied to modulated signal s2(t) may be
regularly changed as follows: from 16-QAM to 16-APSK, to 16-QAM in
the IQ plane, to a first mapping method producing a signal point
layout unlike 16-APSK, to 16-QAM in the IQ plane, to a second
mapping method producing a signal point layout unlike 16-APSK, and
so on. As such, the data reception quality can be improved for the
reception device, much like the results obtained by a regular
change of phase described above.
[0424] In addition, the present invention may use any combination
of methods for a regular change of phase, mapping method, and
amplitude, and the transmit signal may transmit with all of these
taken into consideration.
[0425] The present Embodiment may be realized using single-carrier
methods as well as multi-carrier methods. Accordingly, the present
Embodiment may also be realized using, for example, spread-spectrum
communications, OFDM, SC-FDM, SC-OFDM, wavelet OFDM as described in
Non-Patent Literature 7, and so on. As described above, the present
Embodiment describes changing the phase, amplitude, and mapping
methods by performing phase, amplitude, and mapping method
modifications with respect to the time domain t. However, much like
Embodiment 1, the same changes may be carried out with respect to
the frequency domain. That is, considering the phase, amplitude,
and mapping method modification in the time domain t described in
the present Embodiment and replacing t with f (f being the ((sub-)
carrier) frequency) leads to phase, amplitude, and mapping method
modification applicable to the frequency domain. Also, the phase,
amplitude, and mapping method modification of the present
Embodiment is also applicable to phase, amplitude, and mapping
method modification in both the time domain and the frequency
domain.
[0426] Furthermore, in the present Embodiment, symbols other than
data symbols, such as pilot symbols (preamble, unique word, etc) or
symbols transmitting control information, may be arranged within
the frame in any manner.
Embodiment A1
[0427] The present Embodiment describes a method of regularly
changing the phase when encoding is performed using block codes as
described in Non-Patent
[0428] Literature 12 through 15, such as QC (Quasi-Cyclic) LDPC
Codes (not only QC-LDPC but also LDPC codes may be used),
concatenated LDPC and BCH (Bose-Chaudhuri-Hocquenghem) codes, Turbo
codes or Duo-Binary Turbo Codes using tail-biting, and so on. The
following example considers a case where two streams s1 and s2 are
transmitted. When encoding has been performed using block codes and
control information and the like is not necessary, the number of
bits making up each encoded block matches the number of bits making
up each block code (control information and so on described below
may yet be included). When encoding has been performed using block
codes or the like and control information or the like (e.g., CRC
transmission parameters) is required, then the number of bits
making up each encoded block is the sum of the number of bits
making up the block codes and the number of bits making up the
information.
[0429] FIG. 34 illustrates the varying numbers of symbols and slots
needed in each encoded block when block codes are used. FIG. 34
illustrates the varying numbers of symbols and slots needed in each
encoded block when block codes are used when, for example, two
streams s1 and s2 are transmitted as indicated by the transmission
device from FIG. 4, and the transmission device has only one
encoder. (Here, the transmission method may be any single-carrier
method or multi-carrier method such as OFDM.)
[0430] As shown in FIG. 34, when block codes are used, there are
6000 bits making up a single encoded block. In order to transmit
these 6000 bits, the number of required symbols depends on the
modulation method, being 3000 for QPSK, 1500 for 16-QAM, and 1000
for 64-QAM.
[0431] Then, given that the transmission device from FIG. 4
transmits two streams simultaneously, 1500 of the aforementioned
3000 symbols needed when the modulation method is QPSK are assigned
to s1 and the other 1500 symbols are assigned to s2. As such, 1500
slots for transmitting the 1500 symbols (hereinafter, slots) are
required for each of s1 and s2.
[0432] By the same reasoning, when the modulation method is 16-QAM,
750 slots are needed to transmit all of the bits making up each
encoded block, and when the modulation method is 64-QAM, 500 slots
are needed to transmit all of the bits making up each encoded
block.
[0433] The following describes the relationship between the
above-defined slots and the phase of multiplication, as pertains to
methods for a regular change of phase.
[0434] Here, five different phase changing values (or phase
changing sets) are assumed as having been prepared for use in the
method for a regular change of phase.
[0435] That is, five different phase changing values (or phase
changing sets) have been prepared for the phase changer of the
transmission device from FIG. 4 (equivalent to the period (cycle)
from Embodiments 1 through 4) (As in FIG. 6, five phase changing
values are needed in order to perform a change of phase with a
period (cycle) of five on precoded baseband signal z2' only. Also,
as in FIG. 26, two phase changing values are needed for each slot
in order to perform the change of phase on both precoded baseband
signals z1' and z2'. These two phase changing values are termed a
phase changing set. Accordingly, five phase changing sets should
ideally be prepared in order to perform a change of phase having a
period (cycle) of five in such circumstances). These five phase
changing values (or phase changing sets) are expressed as PHASE[0],
PHASE[1], PHASE[2], PHASE[3], and PHASE[4].
[0436] For the above-described 1500 slots needed to transmit the
6000 bits making up a single encoded block when the modulation
method is QPSK, PHASE[0] is used on 300 slots, PHASE[1] is used on
300 slots, PHASE[2] is used on 300 slots, PHASE[3] is used on 300
slots, and PHASE[4] is used on 300 slots. This is due to the fact
that any bias in phase usage causes great influence to be exerted
by the more frequently used phase, and that the reception device is
dependent on such influence for data reception quality.
[0437] Further still, for the above-described 500 slots needed to
transmit the 6000 bits making up a single encoded block when the
modulation method is 64-QAM, PHASE[0] is used on 150 slots,
PHASE[1] is used on 150 slots, PHASE[2] is used on 150 slots,
PHASE[3] is used on 150 slots, and PHASE[4] is used on 150
slots.
[0438] Further still, for the above-described 500 slots needed to
transmit the 6000 bits making up a single encoded block when the
modulation method is 64-QAM, PHASE[0] is used on 100 slots,
PHASE[1] is used on 100 slots, PHASE[2] is used on 100 slots,
PHASE[3] is used on 100 slots, and PHASE[4] is used on 100
slots.
[0439] As described above, a method for a regular change of phase
requires the preparation of N phase changing values (or phase
changing sets) (where the N different phases are expressed as
PHASE[0], PHASE[], PHASE[2] . . . PHASE[N-2], PHASE[N-1]). As such,
in order to transmit all of the bits making up a single encoded
block, PHASE[0] is used on K.sub.0 slots, PHASE[1] is used on
K.sub.1 slots, PHASE[i] is used on K.sub.i slots (where i=0, 1, 2 .
. . N-1), and PHASE[N-1] is used on K.sub.N-1 slots, such that
Condition #A01 is met.
(Condition #A01)
[0440] K.sub.0=K.sub.1 . . . =K.sub.i= . . . K.sub.N-1. That is,
K.sub.a=K.sub.b (.A-inverted.a and .A-inverted.b where a, b,=0, 1,
2 . . . N-1; (a being an integer no less than zero and no more than
N-1)a.noteq.b).
[0441] Then, when a communication system that supports multiple
modulation methods selects one such supported modulation method for
use, Condition #A01 must be met for the supported modulation
method.
[0442] However, when multiple modulation methods are supported,
each such modulation method typically uses symbols transmitting a
different number of bits per symbols (though some may happen to use
the same number), Condition #A01 may not be satisfied for some
modulation schemes. In such a case, the following condition applies
instead of Condition #A01.
(Condition #A02)
[0443] The difference between K.sub.a and K.sub.b must be 0 or 1.
That is, |K.sub.a-K.sub.b| must be 0 or 1 (.A-inverted.a,
.A-inverted.b, where a, b=0, 1, 2 . . . N-1, a.noteq.b)
[0444] FIG. 35 illustrates the varying numbers of symbols and slots
needed in each encoded block when block codes are used. FIG. 35
illustrates the varying numbers of symbols and slots needed in each
encoded block when block codes are used when, for example, two
streams s1 and s2 are transmitted as indicated by the transmission
device from FIG. 3 and FIG. 12, and the transmission device has two
encoders. (Here, the transmission method may be any single-carrier
method or multi-carrier method such as OFDM.)
[0445] As shown in FIG. 35, when block codes are used, there are
6000 bits making up a single encoded block. In order to transmit
these 6000 bits, the number of required symbols depends on the
modulation method, being 3000 for QPSK, 1500 for 16-QAM, and 1000
for 64-QAM.
[0446] The transmission device from FIG. 3 and the transmission
device from FIG. 12 each transmit two streams at once, and have two
encoders. As such, the two streams each transmit different code
blocks. Accordingly, when the modulation method is QPSK, two
encoded blocks drawn from s1 and s2 are transmitted within the same
interval, e.g., a first encoded block drawn from s1 is transmitted,
then a second encoded block drawn from s2 is transmitted. As such,
3000 slots are needed in order to transmit the first and second
encoded blocks.
[0447] By the same reasoning, when the modulation scheme is 16-QAM,
1500 slots are needed to transmit all of the bits making up the two
coded blocks, and when the modulation scheme is 64-QAM, 1000 slots
are needed to transmit all of the bits making up the two coded
blocks
[0448] The following describes the relationship between the
above-defined slots and the phase of multiplication, as pertains to
methods for a regular change of phase.
[0449] Here, five different phase changing values (or phase
changing sets) are assumed as having been prepared for use in the
method for a regular change of phase. That is, five different phase
changing values (or phase changing sets) have been prepared for the
phase changer of the transmission device from FIGS. 3 and 12
(equivalent to the period (cycle) from Embodiments 1 through 4) (As
in FIG. 6, five phase changing values are needed in order to
perform a change of phase with a period (cycle) of five on precoded
baseband signal z2' only. Also, as in FIG. 26, two phase changing
values are needed for each slot in order to perform the change of
phase on both precoded baseband signals z1' and z2'. These two
phase changing values are termed a phase changing set. Accordingly,
five phase changing sets should ideally be prepared in order to
perform a change of phase having a period (cycle) of five in such
circumstances). These five phase changing values (or phase changing
sets) are expressed as PHASE[0], PHASE[1], PHASE[2], PHASE[3], and
PHASE [4].
[0450] For the above-described 3000 slots needed to transmit the
6000.times.2 bits making up the two encoded blocks when the
modulation method is QPSK, PHASE[0] is used on 600 slots, PHASE[1]
is used on 600 slots, PHASE[2] is used on 600 slots, PHASE[3] is
used on 600 slots, and PHASE[4] is used on 600 slots. This is due
to the fact that any bias in phase usage causes great influence to
be exerted by the more frequently used phase, and that the
reception device is dependent on such influence for data reception
quality.
[0451] Furthermore, in order to transmit the first coded block,
PHASE[0] is used on slots 600 times, PHASE[1] is used on slots 600
times, PHASE[2] is used on slots 600 times, PHASE[3] is used on
slots 600 times, and PHASE[4] is used on slots 600 times.
Furthermore, in order to transmit the second coded block, PHASE[0]
is used on slots 600 times, PHASE[1] is used on slots 600 times,
PHASE[2] is used on slots 600 times, PHASE[3] is used on slots 600
times, and PHASE[4] is used on slots 600 times.
[0452] Similarly, for the above-described 1500 slots needed to
transmit the 6000.times.2 bits making up the two encoded blocks
when the modulation method is 16-QAM, PHASE[0] is used on 300
slots, PHASE[1] is used on 300 slots, PHASE[2] is used on 300
slots, PHASE[3] is used on 300 slots, and PHASE[4] is used on 300
slots.
[0453] Furthermore, in order to transmit the first coded block,
PHASE[0] is used on slots 300 times, PHASE[1] is used on slots 300
times, PHASE[2] is used on slots 300 times, PHASE[3] is used on
slots 300 times, and PHASE[4] is used on slots 300 times.
Furthermore, in order to transmit the second coded block, PHASE[0]
is used on slots 300 times, PHASE[1] is used on slots 300 times,
PHASE[2] is used on slots 300 times, PHASE[3] is used on slots 300
times, and PHASE[4] is used on slots 300 times.
[0454] Similarly, for the above-described 1000 slots needed to
transmit the 6000.times.2 bits making up the two encoded blocks
when the modulation method is 64-QAM, PHASE[0] is used on 200
slots, PHASE[1] is used on 200 slots, PHASE[2] is used on 200
slots, PHASE[3] is used on 200 slots, and PHASE[4] is used on 200
slots.
[0455] Furthermore, in order to transmit the first coded block,
PHASE[0] is used on slots 200 times, PHASE[1] is used on slots 200
times, PHASE[2] is used on slots 200 times, PHASE[3] is used on
slots 200 times, and PHASE[4] is used on slots 200 times.
Furthermore, in order to transmit the second coded block, PHASE[0]
is used on slots 200 times, PHASE[1] is used on slots 200 times,
PHASE[2] is used on slots 200 times, PHASE[3] is used on slots 200
times, and PHASE[4] is used on slots 200 times.
[0456] As described above, a method for regularly changing the
phase requires the preparation of phase changing values (or phase
changing sets) expressed as PHASE[0], PHASE[1], PHASE[2] . . .
PHASE[N-2], PHASE[N-1]. As such, in order to transmit all of the
bits making up two encoded blocks, PHASE[0] is used on K.sub.0
slots, PHASE[1] is used on K.sub.1 slots, PHASE[i] is used on
K.sub.i slots (where i=0, 1, 2 . . . N-1), and PHASE[N-1] is used
on K.sub.N-1 slots, such that Condition #A03 is met.
(Condition #A03)
[0457] K.sub.0=K.sub.1 . . . =K.sub.i=K.sub.N-1. That is,
K.sub.a=K.sub.b (.A-inverted.a and .A-inverted.b where a, b,=0, 1,
2 . . . N-1, (a being an integer no less than zero and no more than
N-1) a.noteq.b). Further, in order to transmit all of the bits
making up the first coded block, PHASE[0] is used K.sub.0,1 times,
PHASE[1] is used K.sub.1,1 times, PHASE[i] is used K.sub.i,1 times
(where i=0, 1, 2 . . . N-1), and PHASE[N-1] is used K.sub.N-1,1
times, such that Condition #A04 is met.
(Condition #A04)
[0457] [0458] K.sub.0,1=K.sub.1,1= . . . K.sub.i,1= . . .
K.sub.N-1,1. That is, K.sub.a,i=K.sub.b,1 (.A-inverted.a and
.A-inverted.b where a, b,=0, 1, 2 . . . N-1, a.noteq.b).
Furthermore, in order to transmit all of the bits making up the
second coded block, PHASE[0] is used K.sub.0,2 times, PHASE[1] is
used K.sub.1,2 times, PHASE[i] is used K.sub.i,2 times (where i=0,
1, 2 . . . N-1), and PHASE[N-1] is used K.sub.N-1,2 times, such
that Condition #A05 is met.
(Condition #A05)
[0458] [0459] K.sub.0,2=K.sub.1,2= . . . K.sub.i,2= . . .
K.sub.N-1,2. That is, K.sub.a,2=K.sub.b,2 (.A-inverted.a and
.A-inverted.b where a, b,=0, 1, 2 . . . N-1, a.noteq.b).
[0460] Then, when a communication system that supports multiple
modulation methods selects one such supported modulation method for
use, Condition #A03, #A04, and #A05 must be met for the supported
modulation method.
[0461] However, when multiple modulation methods are supported,
each such modulation method typically uses symbols transmitting a
different number of bits per symbol (though some may happen to use
the same number), Conditions #A03, #A04, and #A05 may not be
satisfied for some modulation methods. In such a case, the
following conditions apply instead of Condition #A03, #A04, and
#A05.
(Condition #A06)
[0462] The difference between K.sub.a and K.sub.b satisfies 0 or 1.
That is, |K.sub.a-K.sub.b| satisfies 0 or 1 (.A-inverted.a,
.A-inverted.b, where a, b=0, 1, 2 . . . N-1, a.noteq.b)
(Condition #A07)
[0462] [0463] The difference between K.sub.a,1 and K.sub.b,1
satisfies 0 or 1. That is, |K.sub.a,1-K.sub.b,1| satisfies 0 or 1
(.A-inverted.a, .A-inverted.b, where a, b=0, 1, 2 . . . N-1,
a.noteq.b)
(Condition #A08)
[0463] [0464] The difference between K.sub.a,2 and K.sub.b,2
satisfies 0 or 1. That is, |K.sub.a,2-Kb,2| satisfies 0 or 1
(.A-inverted.a, .A-inverted.b, where a, b=0, 1, 2 . . . N-1,
a.noteq.b)
[0465] As described above, bias among the phases being used to
transmit the encoded blocks is removed by creating a relationship
between the encoded block and the phase of multiplication. As such,
data reception quality may be improved for the reception
device.
[0466] In the present Embodiment, N phase changing values (or phase
changing sets) are needed in order to perform a change of phase
having a period (cycle) of N with the method for a regular change
of phase. As such, N phase changing values (or phase changing sets)
PHASE[0], PHASE[1], PHASE[2] . . . PHASE[N-2], and PHASE[N-1] are
prepared. However, schemes exist for reordering the phases in the
stated order with respect to the frequency domain. No limitation is
intended in this regard. The N phase changing values (or phase
changing sets) may also change the phases of blocks in the time
domain or in the time-frequency domain to obtain a symbol
arrangement as described in Embodiment 1. Although the above
examples discuss a phase changing method with a period (cycle) of
N, the same effects are obtainable using N phase changing values
(or phase changing sets) at random. That is, the N phase changing
values (or phase changing sets) need not always have regular
periodicity. As long as the above-described conditions are
satisfied, great quality data reception improvements are realizable
for the reception device.
[0467] Furthermore, given the existence of modes for spatial
multiplexing MIMO schemes, MIMO schemes using a fixed precoding
matrix, space-time block coding schemes, single-stream
transmission, and schemes using a regular change of phase (the
transmission schemes described in Embodiments 1 through 4), the
transmission device (broadcaster, base station) may select any one
of these transmission schemes.
[0468] As described in Non-Patent Literature 3, spatial
multiplexing MIMO methods involve transmitting signals s1 and s2,
which are mapped using a selected modulation method, on each of two
different antennas. As described in Embodiments 1 through 4, MIMO
methods using a fixed precoding matrix involve performing precoding
only (with no change of phase). Further, space-time block coding
methods are described in Non-Patent Literature 9, 16, and 17.
Single-stream transmission methods involve transmitting signal s1,
mapped with a selected modulation method, from an antenna after
performing predetermined processing.
[0469] Schemes using multi-carrier transmission such as OFDM
involve a first carrier group made up of a plurality of carriers
and a second carrier group made up of a plurality of carriers
different from the first carrier group, and so on, such that
multi-carrier transmission is realized with a plurality of carrier
groups. For each carrier group, any of spatial multiplexing MIMO
schemes, MIMO schemes using a fixed precoding matrix, space-time
block coding schemes, single-stream transmission, and schemes using
a regular change of phase may be used. In particular, schemes using
a regular change of phase on a selected (sub-)carrier group are
preferably used to realize the present Embodiment.
[0470] When a change of phase is performed, then for example, a
phase changing value for PHASE[i] of X radians is performed on only
one precoded baseband signal, the phase changers of FIGS. 3, 4, 5,
12, 25, 29, 51, and 53 multiplies precoded baseband signal z2' by
e.sup.jX. Then, when a change of phase by, for example, a phase
changing set for PHASE[i] of X radians and Y radians is performed
on both precoded baseband signals, the phase changers from FIGS.
26, 27, 28, 52, and 54 multiply precoded baseband signal z2' by
e.sup.jX and multiply precoded baseband signal z1' by e.sup.jY.
Embodiment B1
[0471] The following describes a sample configuration of an
application of the transmission methods and reception methods
discussed in the above embodiments and a system using the
application.
[0472] FIG. 36 illustrates the configuration of a system that
includes devices executing transmission methods and reception
methods described in the above Embodiments. As shown in FIG. 36,
the devices executing transmission methods and reception methods
described in the above Embodiments include various receivers such
as a broadcaster, a television 3611, a DVD recorder 3612, a STB
(set-top box) 3613, a computer 3620, a vehicle-mounted television
3641, a mobile phone 3630 and so on within a digital broadcasting
system 3600. Specifically, the broadcaster 3601 uses a transmission
method discussed in the above-described Embodiments to transmit
multiplexed data, in which video, audio, and other data are
multiplexed, over a predetermined transmission band.
[0473] The signals transmitted by the broadcaster 3601 are received
by an antenna (such as antenna 3660 or 3640) embedded within or
externally connected to each of the receivers. Each receiver
obtains the multiplexed data by using reception methods discussed
in the above-described Embodiments to demodulate the signals
received by the antenna. Accordingly, the digital broadcasting
system 3600 is able to realize the effects of the present
invention, as discussed in the above-described Embodiments.
[0474] The video data included in the multiplexed data are coded
with a video coding method compliant with a standard such as MPEG-2
(Moving Picture Experts Group), MPEG4-AVC (Advanced Video Coding),
VC-1, or the like. The audio data included in the multiplexed data
are encoded with an audio coding method compliant with a standard
such as Dolby AC-3 (Audio Coding), Dolby Digital Plus, MLP
(Meridian Lossless Packing), DTS (Digital Theatre Systems), DTS-HD,
Linear PCM (Pulse-Code Modulation), or the like.
[0475] FIG. 37 illustrates the configuration of a receiver 7900
that executes a reception method described in the above-described
Embodiments. The receiver 3700 corresponds to a receiver included
in one of the television 3611, the DVD recorder 3612, the STB 3613,
the computer 3620, the vehicle-mounted television 3641, the mobile
phone 3630 and so on from FIG. 36. The receiver 3700 includes a
tuner 3701 converting a high-frequency signal received by an
antenna 3760 into a baseband signal, and a demodulator 3702
demodulating the baseband signal so converted to obtain the
multiplexed data. The demodulator 3702 executes a reception method
discussed in the above-described Embodiments, and thus achieves the
effects of the present invention as explained above.
[0476] The receiver 3700 further includes a stream interface 3720
that demultiplexes the audio and video data in the multiplexed data
obtained by the demodulator 3702, a signal processor 3704 that
decodes the video data obtained from the demultiplexed video data
into a video signal by applying a video decoding method
corresponding thereto and decodes the audio data obtained from the
demultiplexed audio data into an audio signal by applying an audio
decoding method corresponding thereto, an audio output unit 3706
that outputs the decoded audio signal through a speaker or the
like, and a video display unit 3707 that outputs the decoded video
signal on a display or the like.
[0477] When, for example, a user uses a remote control 3750,
information for a selected channel (selected (television) program
or audio broadcast) is transmitted to an operation input unit 3710.
Then, the receiver 3700 performs processing on the received signal
received by the antenna 3760 that includes demodulating the signal
corresponding to the selected channel, performing error-correcting
decoding, and so on, in order to obtain the received data. At this
point, the receiver 3700 obtains control symbol information that
includes information on the transmission method (the transmission
method, modulation method, error-correction method, and so on from
the above-described Embodiments) (as described using FIGS. 5 and
41) from control symbols included the signal corresponding to the
selected channel. As such, the receiver 3700 is able to correctly
set the reception operations, demodulation method, error-correction
method and so on, thus enabling the data included in the data
symbols transmitted by the broadcaster (base station) to be
obtained. Although the above description is given for an example of
the user using the remote control 3750, the same operations apply
when the user presses a selection key embedded in the receiver 3700
to select a channel.
[0478] According to this configuration, the user is able to view
programs received by the receiver 3700.
[0479] The receiver 3700 pertaining to the present Embodiment
further includes a drive 3708 that may be a magnetic disk, an
optical disc, a non-volatile semiconductor memory, or a similar
recording medium. The receiver 3700 stores data included in the
demultiplexed data obtained through demodulation by the demodulator
3702 and error-correcting decoding (in some circumstances, the data
obtained through demodulation by the demodulator 3702 may not be
subject to error correction. Also, the receiver 3700 may perform
further processing after error correction. The same hereinafter
applies to similar statements concerning other components), data
corresponding to such data (e.g., data obtained through compression
of such data), data obtained through audio and video processing,
and so on, on the drive 3708. Here, an optical disc is a recording
medium, such as DVD (Digital Versatile Disc) or BD (Blu-ray Disc),
that is readable and writable with the use of a laser beam. A
magnetic disk is a floppy disk, a hard disk, or similar recording
medium on which information is storable through the use of magnetic
flux to magnetize a magnetic body. A non-volatile semiconductor
memory is a recording medium, such as flash memory or ferroelectric
random access memory, composed of semiconductor element(s).
Specific examples of non-volatile semiconductor memory include an
SD card using flash memory and a Flash SSD (Solid State Drive).
Naturally, the specific types of recording media mentioned herein
are merely examples. Other types of recording mediums may also be
used.
[0480] According to this structure, the user is able to record and
store programs received by the receiver 3700, and is thereby able
to view programs at any given time after broadcasting by reading
out the recorded data thereof.
[0481] Although the above explanations describe the receiver 3700
storing multiplexed data obtained through demodulation by the
demodulator 3702 and error-correcting decoding on the drive 3708, a
portion of the data included in the multiplexed data may instead be
extracted and recorded. For example, when data broadcasting
services or similar content is included along with the audio and
video data in the multiplexed data obtained through demodulation by
the demodulator 3702 and error-correcting decoding, the audio and
video data may be extracted from the multiplexed data demodulated
by the demodulator 3702 and stored as new multiplexed data.
Furthermore, the drive 3708 may store either the audio data or the
video data included in the multiplexed data obtained through
demodulation by the demodulator 3702 and error-correcting decoding
as new multiplexed data. The aforementioned data broadcasting
service content included in the multiplexed data may also be stored
on the drive 3708.
[0482] Furthermore, when a television, recording device (e.g., a
DVD recorder, BD recorder HDD recorder, SD card, or similar), or
mobile phone incorporating the receiver 3700 of the present
invention receives multiplexed data obtained through demodulation
by the demodulator 3702 and error-correcting decoding that includes
data for correcting bugs in software used to operate the television
or recording device, for correcting bugs in software for preventing
personal information and recorded data from being leaked, and so
on, such software bugs may be corrected by installing the data on
the television or recording device. As such, bugs in the receiver
3700 are corrected through the inclusion of data for correcting
bugs in the software of the receiver 3700. Accordingly, the
television, recording device, or mobile phone incorporating the
receiver 3700 may be made to operate more reliably.
[0483] Here, the process of extracting a portion of the data
included in the multiplexed data obtained through demodulation by
the demodulator 3702 and error-correcting decoding is performed by,
for example, the stream interface 3703. Specifically, the stream
interface 3703, demultiplexes the various data included in the
multiplexed data demodulated by the demodulator 3702, such as audio
data, video data, data broadcasting service content, and so on, as
instructed by a non-diagrammed controller such as a CPU. The stream
interface 3703 then extracts and multiplexes only the indicated
demultiplexed data, thus generating new multiplexed data. The data
to be extracted from the demultiplexed data may be determined by
the user or may be determined in advance according to the type of
recording medium.
[0484] According to such a structure, the receiver 3700 is able to
extract and record only the data needed in order to view the
recorded program. As such, the amount of data to be recorded can be
reduced.
[0485] Although the above explanation describes the drive 3708 as
storing multiplexed data obtained through demodulation by the
demodulator 3702 and error-correcting decoding, the video data
included in the multiplexed data so obtained may be converted by
using a different video coding method than the original video
coding method applied thereto, so as to reduce the amount of data
or the bit rate thereof. The drive 3708 may then store the
converted video data as new multiplexed data. Here, the video
coding method used to generate the new video data may conform to a
different standard than that used to generate the original video
data. Alternatively, the same video coding method may be used with
different parameters. Similarly, the audio data included in the
multiplexed data obtained through demodulation by the demodulator
3702 and error-correcting decoding may be converted by using a
different audio coding method than the original audio coding method
applied thereto, so as to reduce the amount of data or the bit rate
thereof. The drive 3708 may then store the converted audio data as
new multiplexed data.
[0486] Here, the process by which the audio or video data included
in the multiplexed data obtained through demodulation by the
demodulator 3702 and error-correcting decoding is converted so as
to reduce the amount of data or the bit rate thereof is performed
by, for example, the stream interface 3703 or the signal processor
3704. Specifically, the stream interface 3703 demultiplexes the
various data included in the multiplexed data demodulated by the
demodulator 3702, such as audio data, video data, data broadcasting
service content, and so on, as instructed by an undiagrammed
controller such as a CPU. The signal processor 3704 then performs
processing to convert the video data so demultiplexed by using a
different video coding method than the original video coding method
applied thereto, and performs processing to convert the audio data
so demultiplexed by using a different video coding method than the
original audio coding method applied thereto. As instructed by the
controller, the stream interface 3703 then multiplexes the
converted audio and video data, thus generating new multiplexed
data. The signal processor 3704 may, in accordance with
instructions from the controller, performing conversion processing
on either the video data or the audio data, alone, or may perform
conversion processing on both types of data. In addition, the
amounts of video data and audio data or the bit rate thereof to be
obtained by conversion may be specified by the user or determined
in advance according to the type of recording medium.
[0487] According to such a structure, the receiver 3700 is able to
modify the amount of data or the bitrate of the audio and video
data for storage according to the data storage capacity of the
recording medium, or according to the data reading or writing speed
of the drive 3708. Therefore, programs can be stored on the drive
despite the storage capacity of the recording medium being less
than the amount of multiplexed data obtained through demodulation
by the demodulator 3702 and error-correcting decoding, or the data
reading or writing speed of the drive being lower than the bit rate
of the demultiplexed data obtained through demodulation by the
demodulator 3702. As such, the user is able to view programs at any
given time after broadcasting by reading out the recorded data.
[0488] The receiver 3700 further includes a stream output interface
3709 that transmits the multiplexed data demultiplexed by the
demodulator 3702 to external devices through a communications
medium 3730. The stream output interface 3709 may be, for example,
a wireless communication device transmitting modulated multiplexed
data to an external device using a wireless transmission method
conforming to a wireless communication standard such as Wi-Fi.TM.
(IEEE 802.11a, IEEE 802.11b, IEEE 802.11g, IEEE 802.11n, and so
on), WiGiG, WirelessHD, Bluetooth.TM., ZigBee.TM., and so on
through a wireless medium (corresponding to the communications
medium 3730). The stream output interface 3709 may also be a wired
communication device transmitting modulated multiplexed data to an
external device using a communication method conforming to a wired
communication standard such as Ethernet.TM., USB (Universal Serial
Bus), PLC (Power Line Communication), HDMI (High-Definition
Multimedia Interface) and so on through a wired transmission path
(corresponding to the communications medium 3730) connected to the
stream output interface 3709.
[0489] According to this configuration, the user is able to use an
external device with the multiplexed data received by the receiver
3700 using the reception method described in the above-described
Embodiments. The usage of multiplexed data by the user here
includes use of the multiplexed data for real-time viewing on an
external device, recording of the multiplexed data by a recording
unit included in an external device, and transmission of the
multiplexed data from an external device to a yet another external
device.
[0490] Although the above explanations describe the receiver 3700
outputting multiplexed data obtained through demodulation by the
demodulator 3702 and error-correcting decoding through the stream
output interface 3709, a portion of the data included in the
multiplexed data may instead be extracted and output. For example,
when data broadcasting services or similar content is included
along with the audio and video data in the multiplexed data
obtained through demodulation by the demodulator 3702 and
error-correcting decoding, the audio and video data may be
extracted from the multiplexed data obtained through demodulation
by the demodulator 3702 and error-correcting decoding, multiplexed
and output by the stream output interface 3709 as new multiplexed
data. In addition, the stream output interface 3709 may store
either the audio data or the video data included in the multiplexed
data obtained through demodulation by the demodulator 3702 and
error-correcting decoding as new multiplexed data.
[0491] Here, the process of extracting a portion of the data
included in the multiplexed data obtained through demodulation by
the demodulator 3702 and error-correcting decoding is performed by,
for example, the stream interface 3703. Specifically, the stream
interface 3703 demultiplexes the various data included in the
multiplexed data demodulated by the demodulator 3702, such as audio
data, video data, data broadcasting service content, and so on, as
instructed by an undiagrammed controller such as a CPU. The stream
interface 3703 then extracts and multiplexes only the indicated
demultiplexed data, thus generating new multiplexed data. The data
to be extracted from the demultiplexed data may be determined by
the user or may be determined in advance according to the type of
stream output interface 3709.
[0492] According to this structure, the receiver 3700 is able to
extract and output only the required data to an external device. As
such, fewer multiplexed data are output using less communication
bandwidth.
[0493] Although the above explanation describes the stream output
interface 3709 as outputting multiplexed data obtained through
demodulation by the demodulator 3702 and error-correcting decoding,
the video data included in the multiplexed data so obtained may be
converted by using a different video coding method than the
original video coding method applied thereto, so as to reduce the
amount of data or the bit rate thereof. The stream output interface
3709 may then output the converted video data as new multiplexed
data. Here, the video coding method used to generate the new video
data may conform to a different standard than that used to generate
the original video data. Alternatively, the same video coding
method may be used with different parameters. Similarly, the audio
data included in the multiplexed data obtained through demodulation
by the demodulator 3702 and error-correcting decoding may be
converted by using a different audio coding method than the
original audio coding method applied thereto, so as to reduce the
amount of data or the bit rate thereof. The stream output interface
3709 may then output the converted audio data as new multiplexed
data.
[0494] Here, the process by which the audio or video data included
in the multiplexed data obtained through demodulation by the
demodulator 3702 and error-correcting decoding is converted so as
to reduce the amount of data or the bit rate thereof is performed
by, for example, the stream interface 3703 or the signal processor
3704. Specifically, the stream interface 3703 demultiplexes the
various data included in the multiplexed data demodulated by the
demodulator 3702, such as audio data, video data, data broadcasting
service content, and so on, as instructed by an undiagrammed
controller. The signal processor 3704 then performs processing to
convert the video data so demultiplexed by using a different video
coding method than the original video coding method applied
thereto, and performs processing to convert the audio data so
demultiplexed by using a different video coding method than the
original audio coding method applied thereto. As instructed by the
controller, the stream interface 3703 then multiplexes the
converted audio and video data, thus generating new multiplexed
data. The signal processor 3704 may, in accordance with
instructions from the controller, performing conversion processing
on either the video data or the audio data, alone, or may perform
conversion processing on both types of data. In addition, the
amounts of video data and audio data or the bit rate thereof to be
obtained by conversion may be specified by the user or determined
in advance according to the type of stream output interface
3709.
[0495] According to this structure, the receiver 3700 is able to
modify the bit rate of the video and audio data for output
according to the speed of communication with the external device.
Thus, despite the speed of communication with an external device
being slower than the bit rate of the multiplexed data obtained
through demodulation by the demodulator 3702 and error-correcting
decoding, by outputting new multiplexed data from the stream output
interface to the external device, the user is able to use the new
multiplexed data with other communication devices.
[0496] The receiver 3700 further includes an audiovisual output
interface 3711 that outputs audio and video signals decoded by the
signal processor 3704 to the external device through an external
communications medium. The audiovisual output interface 3711 may
be, for example, a wireless communication device transmitting
modulated audiovisual data to an external device using a wireless
transmission method conforming to a wireless communication standard
such as Wi-Fi.TM. (IEEE 802.11a, IEEE 802.11b, IEEE 802.11g, IEEE
802.11n, and so on), WiGig, WirelessHD, Bluetooth.TM., ZigBee.TM.,
and so on through a wireless medium. The stream output interface
3709 may also be a wired communication device transmitting
modulated audiovisual data to an external device using a
communication method conforming to a wired communication standard
such as Ethernet.TM., USB, PLC, HDMI, and so on through a wired
transmission path connected to the stream output interface 3709.
Furthermore, the stream output interface 3709 may be a terminal for
connecting a cable that outputs analogue audio signals and video
signals as-is.
[0497] According to such a structure, the user is able to use the
audio signals and video signals decoded by the signal processor
3704 with an external device.
[0498] Further, the receiver 3700 includes an operation input unit
3710 that receives user operations as input. The receiver 3700
behaves in accordance with control signals input by the operation
input unit 3710 according to user operations, such as by switching
the power supply ON or OFF, changing the channel being received,
switching subtitle display ON or OFF, switching between languages,
changing the volume output by the audio output unit 3706, and
various other operations, including modifying the settings for
receivable channels and the like.
[0499] The receiver 3700 may further include functionality for
displaying an antenna level representing the received signal
quality while the receiver 3700 is receiving a signal. The antenna
level may be, for example, a index displaying the received signal
quality calculated according to the RSSI (Received Signal Strength
Indicator), the received signal magnetic field strength, the C/N
(carrier-to-noise) ratio, the BER, the packet error rate, the frame
error rate, the channel state information, and so on, received by
the receiver 3700 and indicating the level and the quality of a
received signal. In such circumstances, the demodulator 3702
includes a signal quality calibrator that measures the RSSI, the
received signal magnetic field strength, the C/N ratio, the BER,
the packet error rate, the frame error rate, the channel state
information, and so on. In response to user operations, the
receiver 3700 displays the antenna level (signal level, signal
quality) in a user-recognizable format on the video display unit
3707. The display format for the antenna level (signal level,
signal quality) may be a numerical value displayed according to the
RSSI, the received signal magnetic field strength, the C/N ratio,
the BER, the packet error rate, the frame error rate, the channel
state information, and so on, or may be an image display that
varies according to the RSSI, the received signal magnetic field
strength, the C/N ratio, the BER, the packet error rate, the frame
error rate, the channel state information, and so on. The receiver
3700 may display multiple antenna level (signal level, signal
quality) calculated for each stream s1, s2, and so on demultiplexed
using the reception method discussed in the above-described
Embodiments, or may display a single antenna level (signal level,
signal quality) calculated for all such streams. When the video
data and audio data composing a program are transmitted
hierarchically, the signal level (signal quality) may also be
displayed for each hierarchical level.
[0500] According to the above structure, the user is given an
understanding of the antenna level (signal level, signal quality)
numerically or visually during reception using the reception
methods discussed in the above-described Embodiments.
[0501] Although the above example describes the receiver 3700 as
including the audio output unit 3706, the video display unit 3707,
the drive 3708, the stream output interface 3709, and the
audiovisual output interface 3711, all of these components are not
strictly necessary. As long as the receiver 3700 includes at least
one of the above-described components, the user is able to use the
multiplexed data obtained through demodulation by the demodulator
3702 and error-correcting decoding. Any receiver may be freely
combined with the above-described components according to the usage
method.
(Multiplexed Data)
[0502] The following is a detailed description of a sample
configuration of multiplexed data. The data configuration typically
used in broadcasting is an MPEG-2 transport stream (TS). Therefore
the following description describes an example related to MPEG2-TS.
However, the data configuration of the multiplexed data transmitted
by the transmission and reception methods discussed in the
above-described Embodiments is not limited to MPEG2-TS. The
advantageous effects of the above-described Embodiments are also
achievable using any other data structure.
[0503] FIG. 38 illustrates a sample configuration for multiplexed
data. As shown, the multiplexed data are elements making up
programmes (or events, being a portion thereof) currently provided
by various services. For example, one or more video streams, audio
streams, presentation graphics (PG) streams, interactive graphics
(IG) streams, and other such element streams are multiplexed to
obtain the multiplexed data. When a broadcast program provided by
the multiplexed data is a movie, the video streams represent main
video and sub video of the movie, the audio streams represent main
audio of the movie and sub-audio to be mixed with the main audio,
and the presentation graphics streams represent subtitles for the
movie. Main video refers to video images normally presented on a
screen, whereas sub-video refers to video images (for example,
images of text explaining the outline of the movie) to be presented
in a small window inserted within the video images. The interactive
graphics streams represent an interactive display made up of GUI
(Graphical User Interface) components presented on a screen.
[0504] Each stream included in the multiplexed data is identified
by an identifier, termed a PID, uniquely assigned to the stream.
For example, PID 0x1011 is assigned to the video stream used for
the main video of the movie, PIDs 0x1100 through 0x111F are
assigned to the audio streams, PIDs 0x1200 through 0x121F are
assigned to the presentation graphics, PIDs 0x1400 through 0x141F
are assigned to the interactive graphics, PIDs 0x1B00 through
0x1B1F are assigned to the video streams used for the sub-video of
the movie, and PIDs 0x1A00 through 0x1A1F are assigned to the audio
streams used as sub-audio to be mixed with the main audio of the
movie.
[0505] FIG. 39 is a schematic diagram illustrating an example of
the multiplexed data being multiplexed. First, a video stream 3901,
made up of a plurality of frames, and an audio stream 3904, made up
of a plurality of audio frames, are respectively converted into PES
packet sequence 3902 and 3905, then further converted into TS
packets 3903 and 3906. Similarly, a presentation graphics stream
3911 and an interactive graphics stream 3914 are respectively
converted into PES packet sequence 3912 and 3915, then further
converted into TS packets 3913 and 3916. The multiplexed data 3917
is made up of the TS packets 3903, 3906, 3913, and 3916 multiplexed
into a single stream.
[0506] FIG. 40 illustrates further details of a PES packet sequence
as contained in the video stream. The first tier of FIG. 40 shows a
video frame sequence in the video stream. The second tier shows a
PES packet sequence. Arrows yy1, yy2, yy3, and yy4 indicate the
plurality of Video Presentation Units, which are I-pictures,
B-pictures, and P-pictures, in the video stream as divided and
individually stored as the payload of a PES packet. Each PES packet
has a PES header. A PES header contains a PTS (Presentation Time
Stamp) at which the picture is to be displayed, a DTS (Decoding
Time Stamp) at which the picture is to be decoded, and so on.
[0507] FIG. 41 illustrates the structure of a TS packet as
ultimately written into the multiplexed data. A TS packet is a
188-byte fixed-length packet made up of a 4-byte PID identifying
the stream and of a 184-byte TS payload containing the data. The
above-described PES packets are divided and individually stored as
the TS payload. For a BD-ROM, each TS packet has a 4-byte
TP_Extra_Header affixed thereto to build a 192-byte source packet,
which is to be written as the multiplexed data. The TP_Extra_Header
contains information such as an Arrival_Time_Stamp (ATS). The ATS
indicates a time for starring transfer of the TS packet to the PID
filter of a decoder. The multiplexed data are made up of source
packets arranged as indicated in the bottom tier of FIG. 41. A SPN
(source packet number) is incremented for each packet, beginning at
the head of the multiplexed data.
[0508] In addition to the video streams, audio streams,
presentation graphics streams, and the like, the TS packets
included in the multiplexed data also include a PAT (Program
Association Table), a PMT (Program Map Table), a PCR (Program Clock
Reference) and so on. The PAT indicates the PID of a PMT used in
the multiplexed data, and the PID of the PAT itself is registered
as 0. The PMT includes PIDs identifying the respective streams,
such as video, audio and subtitles, contained in the multiplexed
data and attribute information (frame rate, aspect ratio, and the
like) of the streams identified by the respective PIDs. In
addition, the PMT includes various types of descriptors relating to
the multiplexed data. One such descriptor may be copy control
information indicating whether or not copying of the multiplexed
data is permitted. The PCR includes information for synchronizing
the ATC (Arrival Time Clock) serving as the chronological axis of
the ATS to the STC (System Time Clock) serving as the chronological
axis of the PTS and DTS. Each PCR packet includes an STC time
corresponding to the ATS at which the packet is to be transferred
to the decoder.
[0509] FIG. 42 illustrates the detailed data configuration of a
PMT. The PMT starts with a PMT header indicating the length of the
data contained in the PMT. Following the PMT header, descriptors
pertaining to the multiplexed data are arranged. One example of a
descriptor included in the PMT is the copy control information
described above. Following the descriptors, stream information
pertaining to the respective streams included in the multiplexed
data is arranged. Each piece of stream information is composed of
stream descriptors indicating a stream type identifying a
compression codec employed for a corresponding stream, a PID for
the stream, and attribute information (frame rate, aspect ratio,
and the like) of the stream. The PMT includes the same number of
stream descriptors as the number of streams included in the
multiplexed data.
[0510] When recorded onto a recoding medium or the like, the
multiplexed data are recorded along with a multiplexed data
information file.
[0511] FIG. 43 illustrates a sample configuration for the
multiplexed data information file. As shown, the multiplexed data
information file is management information for the multiplexed
data, is provided in one-to-one correspondence with the multiplexed
data, and is made up of multiplexed data information, stream
attribute information, and an entry map.
[0512] The multiplexed data information is made up of a system
rate, a playback start time, and a playback end time. The system
rate indicates the maximum transfer rate of the multiplexed data to
the PID filter of a later-described system target decoder. The
multiplexed data includes ATS at an interval set so as not to
exceed the system rate. The playback start time is set to the time
specified by the PTS of the first video frame in the multiplexed
data, whereas the playback end time is set to the time calculated
by adding the playback duration of one frame to the PTS of the last
video frame in the multiplexed data.
[0513] FIG. 44 illustrates a sample configuration for the stream
attribute information included in the multiplexed data information
file. As shown, the stream attribute information is attribute
information for each stream included in the multiplexed data,
registered for each PID. That is, different pieces of attribute
information are provided for different streams, namely for the
video streams, the audio streams, the presentation graphics
streams, and the interactive graphics streams. The video stream
attribute information indicates the compression codec employed to
compress the video stream, the resolution of individual pictures
constituting the video stream, the aspect ratio, the frame rate,
and so on. The audio stream attribute information indicates the
compression codec employed to compress the audio stream, the number
of channels included in the audio stream, the language of the audio
stream, the sampling frequency, and so on. This information is used
to initialize the decoder before playback by a player.
[0514] In the present Embodiment, the stream type included in the
PMT is used among the information included in the multiplexed data.
When the multiplexed data are recorded on a recording medium, the
video stream attribute information included in the multiplexed data
information file is used. Specifically, the video coding method and
device described in any of the above Embodiments may be modified to
additionally include a step or unit of setting a specific piece of
information in the stream type included in the PMT or in the video
stream attribute information. The specific piece of information is
for indicating that the video data are generated by the video
coding method and device described in the Embodiment. According to
such a structure, video data generated by the video coding method
and device described in any of the above Embodiments is
distinguishable from video data compliant with other standards.
[0515] FIG. 45 illustrates a sample configuration of an audiovisual
output device 4500 that includes a reception device 4504 receiving
a modulated signal that includes audio and video data transmitted
by a broadcaster (base station) or data intended for broadcasting.
The configuration of the reception device 4504 corresponds to the
reception device 3700 from FIG. 37. The audiovisual output device
4500 incorporates, for example, an OS (Operating System), or
incorporates a communication device 4506 for connecting to the
Internet (e.g., a communication device intended for a wireless LAN
(Local Area Network) or for Ethernet). As such, a video display
unit 4501 is able to simultaneously display audio and video data,
or video in video data for broadcast 4502, and hypertext 4503 (from
the World Wide Web) provided over the Internet. By operating a
remote control 4507 (alternatively, a mobile phone or keyboard),
either of the video in video data for broadcast 4502 and the
hypertext 4503 provided over the Internet may be selected to change
operations. For example, when the hypertext 4503 provided over the
Internet is selected, the website displayed may be changed by
remote control operations. When audio and video data, or video in
video data for broadcast 4502 is selected, information from a
selected channel (selected (television) program or audio broadcast)
may be transmitted by the remote control 4507. As such, an
interface 4505 obtains the information transmitted by the remote
control. The reception device 4504 performs processing such as
demodulation and error-correction corresponding to the selected
channel, thereby obtaining the received data. At this point, the
reception device 4504 obtains control symbol information that
includes information on the transmission method (as described using
FIG. 5) from control symbols included the signal corresponding to
the selected channel. As such, the reception device 4504 is able to
correctly set the reception operations, demodulation method,
error-correction method and so on, thus enabling the data included
in the data symbols transmitted by the broadcaster (base station)
to be obtained. Although the above description is given for an
example of the user using the remote control 4507, the same
operations apply when the user presses a selection key embedded in
the audiovisual output device 4500 to select a channel.
[0516] In addition, the audiovisual output device 4500 may be
operated using the Internet. For example, the audiovisual output
device 4500 may be made to record (store) a program through another
terminal connected to the Internet. (Accordingly, the audiovisual
output device 4500 should include the drive 3708 from FIG. 37.) The
channel is selected before recording begins. As such, the reception
device 4504 performs processing such as demodulation and
error-correction corresponding to the selected channel, thereby
obtaining the received data. At this point, the reception device
4504 obtains control symbol information that includes information
on the transmission method (the transmission method, modulation
method, error-correction method, and so on from the above-described
Embodiments) (as described using FIG. 5) from control symbols
included the signal corresponding to the selected channel. As such,
the reception device 4504 is able to correctly set the reception
operations, demodulation method, error-correction method and so on,
thus enabling the data included in the data symbols transmitted by
the broadcaster (base station) to be obtained.
(Supplement)
[0517] The present description considers a
communications/broadcasting device such as a broadcaster, a base
station, an access point, a terminal, a mobile phone, or the like
provided with the transmission device, and a communications device
such as a television, radio, terminal, personal computer, mobile
phone, access point, base station, or the like provided with the
reception device. The transmission device and the reception device
pertaining to the present invention are communication devices in a
form able to execute applications, such as a television, radio,
personal computer, mobile phone, or similar, through connection to
some sort of interface (e.g., USB).
[0518] Furthermore, in the present Embodiment, symbols other than
data symbols, such as pilot symbols (namely preamble, unique word,
postamble, reference symbols, scattered pilot symbols and so on),
symbols intended for control information, and so on may be freely
arranged within the frame. Although pilot symbols and symbols
intended for control information are presently named, such symbols
may be freely named otherwise as the function thereof remains the
important consideration.
[0519] Provided that a pilot symbol, for example, is a known symbol
modulated with PSK modulation in the transmitter and receiver
(alternatively, the receiver may be synchronized such that the
receiver knows the symbols transmitted by the transmitter), the
receiver is able to use this symbol for frequency synchronization,
time synchronization, channel estimation (CSI (Channel State
Information) estimation for each modulated signal), signal
detection, and the like.
[0520] The symbols intended for control information are symbols
transmitting information (such as the modulation method,
error-correcting coding method, encoding rate of error-correcting
codes, and setting information for the top layer used in
communications) that must be transmitted to the receiving party in
order to execute transmission of non-data (i.e., applications).
[0521] The present invention is not limited to the Embodiments, but
may also be realized in various other ways. For example, while the
above Embodiments describe communication devices, the present
invention is not limited to such devices and may be implemented as
software for the corresponding communications method.
[0522] Although the above-described Embodiments describe phase
changing methods for methods of transmitting two modulated signals
from two antennas, no limitation is intended in this regard.
Precoding and a change of phase may be performed on four signals
that have been mapped to generate four modulated signals
transmitted using four antennas. That is, the present invention is
applicable to performing a change of phase on N signals that have
been mapped and precoded to generate N modulated signals
transmitted using N antennas.
[0523] Although the above-described Embodiments describe examples
of systems where two modulated signals are transmitted from two
antennas and received by two respective antennas in a MIMO
communications system, the present invention is not limited in this
regard and is also applicable to MISO (Multiple Input Single
Output) communications systems. In a MISO system, the reception
device does not include antenna 701_Y, wireless unit 703_Y, channel
fluctuation estimator 707_1 for modulated signal z1, and channel
fluctuation estimator 707_2 for modulated signal z2 from FIG. 7.
However, the processing described in Embodiment 1 may still be
executed to estimate r1 and r2. Technology for receiving and
decoding a plurality of signals transmitted simultaneously at a
common frequency are received by a single antenna is widely known.
The present invention is additional processing supplementing
conventional technology for a signal processor reverting a phase
changed by the transmitter.
[0524] Although the present invention describes examples of systems
where two modulated signals are transmitted from two antennas and
received by two respective antennas in a MIMO communications
system, the present invention is not limited in this regard and is
also applicable to MISO systems. In a MISO system, the transmission
device performs precoding and change of phase such that the points
described thus far are applicable. However, the reception device
does not include antenna 701_Y, wireless unit 703_Y, channel
fluctuation estimator 707_1 for modulated signal z1, and channel
fluctuation estimator 707_2 for modulated signal z2 from FIG. 7.
However, the processing described in the present description may
still be executed to estimate the data transmitted by the
transmission device. Technology for receiving and decoding a
plurality of signals transmitted simultaneously at a common
frequency are received by a single antenna is widely known (a
single-antenna receiver may apply ML operations (Max-log APP or
similar)). The present invention may have the signal processor 711
from FIG. 7 perform demodulation (detection) by taking the
precoding and change of phase applied by the transmitter into
consideration.
[0525] The present description uses terms such as precoding,
precoding weights, precoding matrix, and so on. The terminology
itself may be otherwise (e.g., may be alternatively termed a
codebook) as the key point of the present invention is the signal
processing itself.
[0526] Furthermore, although the present description discusses
examples mainly using OFDM as the transmission method, the
invention is not limited in this manner. Multi-carrier methods
other than OFDM and single-carrier methods may all be used to
achieve similar Embodiments. Here, spread-spectrum communications
may also be used. When single-carrier methods are used, the change
of phase is performed with respect to the time domain.
[0527] In addition, although the present description discusses the
use of ML operations, APP, Max-log APP, ZF, MMSE and so on by the
reception device, these operations may all be generalized as wave
detection, demodulation, detection, estimation, and demultiplexing
as the soft results (log-likelihood and log-likelihood ratio) and
the hard results (zeroes and ones) obtained thereby are the
individual bits of data transmitted by the transmission device.
[0528] Different data may be transmitted by each stream s1(t) and
s2(t) (s1(i), s2(i)), or identical data may be transmitted
thereby.
[0529] The two stream baseband signals s1(i) and s2(i) (where i
indicates sequence (with respect to time or (carrier) frequency))
undergo precoding and a regular change of phase (the order of
operations may be freely reversed) to generate two post-processing
baseband signals z1(i) and z2(i). For post-processing baseband
signal z1(i), the in-phase component I is I.sub.1(i) while the
quadrature component is Q.sub.1(i), and for post processing
baseband signal z2(i), the in-phase component is I.sub.1(i) while
the quadrature component is Q.sub.2(i). The baseband components may
be switched, as long as the following holds.
[0530] Let the in-phase component and the quadrature component of
switched baseband signal r1(i) be I.sub.1(i) and Q.sub.2(i), and
the in-phase component and the quadrature component of switched
baseband signal r2(i) be I.sub.2(i) and Q.sub.1(i). The modulated
signal corresponding to switched baseband signal r1(i) is
transmitted by transmit antenna 1 and the modulated signal
corresponding to switched baseband signal r2(i) is transmitted from
transmit antenna 2, simultaneously on a common frequency. As such,
the modulated signal corresponding to switched baseband signal
r1(i) and the modulated signal corresponding to switched baseband
signal r2(i) are transmitted from different antennas,
simultaneously on a common frequency. Alternatively, [0531] For
switched baseband signal r1(i), the in-phase component may be
I.sub.1(i) while the quadrature component may be I.sub.2(i), and
for switched baseband signal r2(i), the in-phase component may be
Q.sub.1(i) while the quadrature component may be Q.sub.2(i). [0532]
For switched baseband signal r1(i), the in-phase component may be
I.sub.2(i) while the quadrature component may be I.sub.1(i), and
for switched baseband signal r2(i), the in-phase component may be
Q.sub.1(i) while the quadrature component may be Q.sub.2(i). [0533]
For switched baseband signal r1(i), the in-phase component may be
I.sub.1(i) while the quadrature component may be I.sub.2(i), and
for switched baseband signal r2(i), the in-phase component may be
Q.sub.2(i) while the quadrature component may be Q.sub.1(i). [0534]
For switched baseband signal r1(i), the in-phase component may be
I.sub.2(i) while the quadrature component may be I.sub.1(i), and
for switched baseband signal r2(i), the in-phase component may be
Q.sub.2(i) while the quadrature component may be Q.sub.1(i). [0535]
For switched baseband signal r1(i), the in-phase component may be
I.sub.1(i) while the quadrature component may be Q.sub.2(i), and
for switched baseband signal r2(i), the in-phase component may be
Q.sub.1(i) while the quadrature component may be I.sub.2(i). [0536]
For switched baseband signal r1(i), the in-phase component may be
Q.sub.2(i) while the quadrature component may be I.sub.1(i), and
for switched baseband signal r2(i), the in-phase component may be
I.sub.2(i) while the quadrature component may be Q.sub.1(i). [0537]
For switched baseband signal r1(i), the in-phase component may be
Q.sub.2(i) while the quadrature component may be I.sub.1(i), and
for switched baseband signal r2(i), the in-phase component may be
Q.sub.1(i) while the quadrature component may be I.sub.2(i). [0538]
For switched baseband signal r2(i), the in-phase component may be
I.sub.1(i) while the quadrature component may be I.sub.2(i), and
for switched baseband signal r1(i), the in-phase component may be
Q.sub.1(i) while the quadrature component may be Q.sub.2(i). [0539]
For switched baseband signal r2(i), the in-phase component may be
I.sub.2(i) while the quadrature component may be I.sub.1(i), and
for switched baseband signal r1(i), the in-phase component may be
Q.sub.1(i) while the quadrature component may be Q.sub.2(i). [0540]
For switched baseband signal r2(i), the in-phase component may be
I.sub.1(i) while the quadrature component may be I.sub.2(i), and
for switched baseband signal r1(i), the in-phase component may be
Q.sub.2(i) while the quadrature component may be Q.sub.1(i). [0541]
For switched baseband signal r2(i), the in-phase component may be
I.sub.2(i) while the quadrature component may be I.sub.1(i), and
for switched baseband signal r1(i), the in-phase component may be
Q.sub.2(i) while the quadrature component may be Q.sub.1(i). [0542]
For switched baseband signal r2(i), the in-phase component may be
I.sub.1(i) while the quadrature component may be Q.sub.2(i), and
for switched baseband signal r1(i), the in-phase component may be
I.sub.2(i) while the quadrature component may be Q.sub.1(i). [0543]
For switched baseband signal r2(i), the in-phase component may be
I.sub.1(i) while the quadrature component may be Q.sub.2(i), and
for switched baseband signal r1(i), the in-phase component may be
Q.sub.1(i) while the quadrature component may be I.sub.2(i). [0544]
For switched baseband signal r2(i), the in-phase component may be
Q.sub.2(i) while the quadrature component may be I.sub.1(i), and
for switched baseband signal r1(i), the in-phase component may be
I.sub.2(i) while the quadrature component may be Q.sub.1(i). [0545]
For switched baseband signal r2(i), the in-phase component may be
Q.sub.2(i) while the quadrature component may be I.sub.i(i), and
for switched baseband signal r1(i), the in-phase component may be
Q.sub.1(i) while the quadrature component may be I.sub.2(i).
[0546] Alternatively, although the above description discusses
performing two types of signal processing on both stream signals so
as to switch the in-phase component and quadrature component of the
two signals, the invention is not limited in this manner. The two
types of signal processing may be performed on more than two
streams, so as to switch the in-phase component and quadrature
component thereof.
[0547] Alter, while the above examples describe switching performed
on baseband signals having a common timestamp (common
(sub-)carrier) frequency), the baseband signals being switched need
not necessarily have a common timestamp (common (sub-)carrier)
frequency). For example, any of the following are possible. [0548]
For switched baseband signal r1(i), the in-phase component may be
I.sub.1(i+v) while the quadrature component may be Q.sub.2(i+w),
and for switched baseband signal r2(i), the in-phase component may
be I.sub.2(i+w) while the quadrature component may be Q.sub.1(i+v).
[0549] For switched baseband signal r1(i), the in-phase component
may be I.sub.1(i+v) while the quadrature component may be
Q.sub.2(i+w), and for switched baseband signal r2(i), the in-phase
component may be Q.sub.1(i+v) while the quadrature component may be
Q.sub.2(i+w). [0550] For switched baseband signal r1(i), the
in-phase component may be I.sub.2(i+v) while the quadrature
component may be Q.sub.1(i+w), and for switched baseband signal
r2(i), the in-phase component may be Q.sub.1(i+v) while the
quadrature component may be Q.sub.2(i+w). [0551] For switched
baseband signal r1(i), the in-phase component may be I.sub.1(i+v)
while the quadrature component may be Q.sub.2(i+w), and for
switched baseband signal r2(i), the in-phase component may be
Q.sub.2(i+w) while the quadrature component may be Q.sub.1(i+v).
[0552] For switched baseband signal r1(i), the in-phase component
may be I.sub.2(i+v) while the quadrature component may be
Q.sub.1(i+w), and for switched baseband signal r2(i), the in-phase
component may be Q.sub.2(i+w) while the quadrature component may be
Q.sub.1(i+v). [0553] For switched baseband signal r1(i), the
in-phase component may be I.sub.1(i+v) while the quadrature
component may be Q.sub.2(i+w), and for switched baseband signal
r2(i), the in-phase component may be Q.sub.1(i+v) while the
quadrature component may be I.sub.2(i+w). [0554] For switched
baseband signal r1(i), the in-phase component may be Q.sub.2(i+w)
while the quadrature component may be I.sub.1(i+v), and for
switched baseband signal r2(i), the in-phase component may be
I.sub.2(i+w) while the quadrature component may be Q.sub.1(i+v).
[0555] For switched baseband signal r1(i), the in-phase component
may be Q.sub.2(i+w) while the quadrature component may be
I.sub.1(i+v), and for switched baseband signal r2(i), the in-phase
component may be Q.sub.1(i+v) while the quadrature component may be
I.sub.2(i+w). [0556] For switched baseband signal r2(i), the
in-phase component may be I.sub.1(i+v) while the quadrature
component may be Q.sub.2(i+w), and for switched baseband signal
r1(i), the in-phase component may be Q.sub.1(i+v) while the
quadrature component may be Q.sub.2(i+w). [0557] For switched
baseband signal r2(i), the in-phase component may be I.sub.2(i+v)
while the quadrature component may be Q.sub.1(i+w), and for
switched baseband signal r1(i), the in-phase component may be
Q.sub.1(i+v) while the quadrature component may be Q.sub.2(i+w).
[0558] For switched baseband signal r2(i), the in-phase component
may be I.sub.1(i+v) while the quadrature component may be
Q.sub.2(i+w), and for switched baseband signal r1(i), the in-phase
component may be Q.sub.2(i+w) while the quadrature component may be
Q.sub.1(i+v). [0559] For switched baseband signal r2(i), the
in-phase component may be I.sub.2(i+v) while the quadrature
component may be Q.sub.1(i+w), and for switched baseband signal
r1(i), the in-phase component may be Q.sub.2(i+w) while the
quadrature component may be Q.sub.1(i+v). [0560] For switched
baseband signal r2(i), the in-phase component may be I.sub.1(i+v)
while the quadrature component may be Q.sub.2(i+w), and for
switched baseband signal r1(i), the in-phase component may be
I.sub.2(i+w) while the quadrature component may be Q.sub.1(i+v).
[0561] For switched baseband signal r2(i), the in-phase component
may be I.sub.1(i+v) while the quadrature component may be
Q.sub.2(i+w), and for switched baseband signal r1(i), the in-phase
component may be Q.sub.1(i+v) while the quadrature component may be
I.sub.2(i+w). [0562] For switched baseband signal r2(i), the
in-phase component may be Q.sub.2(i+w) while the quadrature
component may be I.sub.1(i+v), and for switched baseband signal
r1(i), the in-phase component may be I.sub.2(i+w) while the
quadrature component may be Q.sub.1(i+v). [0563] For switched
baseband signal r2(i), the in-phase component may be Q.sub.2(i+w)
while the quadrature component may be I.sub.1(i+v), and for
switched baseband signal r1(i), the in-phase component may be
Q.sub.1(i+v) while the quadrature component may be
I.sub.2(i+w).
[0564] FIG. 55 illustrates a baseband signal switcher 5502
explaining the above. As shown, of the two processed baseband
signals z1(i) 5501_1 and z2(i) 5501_2, processed baseband signal
z1(i) 5501_1 has in-phase component I.sub.1(i) and quadrature
component Q.sub.1(i), while processed baseband signal z2(i) 5501_2
has in-phase component I.sub.2(i) and quadrature component
Q.sub.2(i). Then, after switching, switched baseband signal r1(i)
5503_1 has in-phase component I.sub.r1(i) and quadrature component
Q.sub.r1(i), while switched baseband signal r2(i) 5503_2 has
in-phase component I.sub.r2(i) and quadrature component
Q.sub.r2(i). The in-phase component I.sub.r1(i) and quadrature
component Q.sub.r1(i) of switched baseband signal r1(i) 5503_1 and
the in-phase component I.sub.r2(i) and quadrature component
Q.sub.r2(i) of switched baseband signal r2(i) 5503_2 may be
expressed as any of the above. Although this example describes
switching performed on baseband signals having a common timestamp
(common ((sub-)carrier) frequency) and having undergone two types
of signal processing, the same may be applied to baseband signals
having undergone two types of signal processing but having
different timestamps (different ((sub-)carrier) frequencies).
[0565] Each of the transmit antennas of the transmission device and
each of the receive antennas of the reception device shown in the
figures may be formed by a plurality of antennas.
[0566] The present description uses the symbol V, which is the
universal quantifier, and the symbol .E-backward., which is the
existential quantifier.
[0567] Furthermore, the present description uses the radian as the
unit of phase in the complex plane, e.g., for the argument
thereof.
[0568] When dealing with the complex plane, the coordinates of
complex numbers are expressible by way of polar coordinates. For a
complex number z=a+jb (where a and b are real numbers and j is the
imaginary unit), the corresponding point (a, b) on the complex
plane is expressed with the polar coordinates [r, .theta.],
converted as follows:
a=r.times.cos .theta.
b=r.times.sin .theta.
[Math. 49]
r= {square root over (a.sup.2+b.sup.2)} (formula 49)
[0569] where r is the absolute value of z (r=|z|), and 0 is the
argument thereof. As such, z=a+jb is expressible as
re.sup.j.theta..
[0570] In the present invention, the baseband signals s1, s2, z1,
and z2 are described as being complex signals. A complex signal
made up of in-phase signal I and quadrature signal Q is also
expressible as complex signal I+jQ. Here, either of I and Q may be
equal to zero.
[0571] FIG. 46 illustrates a sample broadcasting system using the
phase changing method described in the present description. As
shown, a video encoder 4601 takes video as input, performs video
encoding, and outputs encoded video data 4602. An audio encoder
4603 takes audio as input, performs audio encoding, and outputs
encoded audio data 4604. A data encoder 4605 takes data as input,
performs data encoding (e.g., data compression), and outputs
encoded data 4606. Taken as a whole, these components form a source
information encoder 4600.
[0572] A transmitter 4607 takes the encoded video data 4602, the
encoded audio data 4604, and the encoded data 4606 as input,
performs error-correcting coding, modulation, precoding, and phase
changing (e.g., the signal processing by the transmission device
from FIG. 3) on a subset of or on the entirety of these, and
outputs transmit signals 4608_1 through 4608_N. Transmit signals
4608_1 through 4608_N are then transmitted by antennas 4609_1
through 4609_N as radio waves.
[0573] A receiver 4612 takes received signals 4611_1 through 4611_M
received by antennas 4610_1 through 4610_M as input, performs
processing such as frequency conversion, change of phase, decoding
of the precoding, log-likelihood ratio calculation, and
error-correcting decoding (e.g., the processing by the reception
device from FIG. 7), and outputs received data 4613, 4615, and
4617. A source information decoder 4619 takes the received data
4613, 4615, and 4617 as input. A video decoder 4614 takes received
data 4613 as input, performs video decoding, and outputs a video
signal. The video is then displayed on a television display. An
audio decoder 4616 takes received data 4615 as input. The audio
decoder 4616 performs audio decoding and outputs an audio signal.
the audio is then played through speakers. A data decoder 4618
takes received data 4617 as input, performs data decoding, and
outputs information.
[0574] In the above-described Embodiments pertaining to the present
invention, the number of encoders in the transmission device using
a multi-carrier transmission method such as OFDM may be any number,
as described above. Therefore, as in FIG. 4, for example, the
transmission device may have only one encoder and apply a method of
distributing output to the multi-carrier transmission method such
as OFDM. In such circumstances, the wireless units 310A and 310B
from FIG. 4 should replace the OFDM-related processors 1301A and
1301B from FIG. 12. The description of the OFDM-related processors
is as given for Embodiment 1.
[0575] Although Embodiment 1 gives Math. 36 (formula 36) as an
example of a precoding matrix, another precoding matrix may also be
used, when the following method is applied.
[ Math . .times. 50 ] ( w .times. .times. 11 w .times. .times. 12 w
.times. .times. 21 w .times. .times. 22 ) = 1 .alpha. 2 + 1 .times.
( e j .times. .times. 0 .alpha. .times. e j .times. .times. .pi.
.alpha. .times. e j .times. .times. 0 e j .times. .times. 0 ) (
formula .times. .times. 50 ) ##EQU00029##
[0576] In the precoding matrices of Math. 36 (formula 36) and Math.
50 (formula 50), the value of a is set as given by Math. 37
(formula 37) and Math. 38 (formula 38). However, no limitation is
intended in this manner. A simple precoding matrix is obtainable by
setting .alpha.=1, which is also a valid value.
[0577] In Embodiment A1, the phase changers from FIGS. 3, 4, 6, 12,
25, 29, 51, and 53 are indicated as having a phase changing value
of PHASE[i] (where i=0, 1, 2, . . . , N-2, N-1) to achieve a period
(cycle) of N (value reached given that FIGS. 3, 4, 6, 12, 25, 29,
51, and 53 perform a change of phase on only one baseband signal).
The present description discusses performing a change of phase on
one precoded baseband signal (i.e., in FIGS. 3, 4, 6, 12, 25, 29,
51 and 53) namely on precoded baseband signal z2'. Here, PHASE[k]
is calculated as follows.
[ Math . .times. 51 ] PHASE .times. [ k ] = 2 .times. .times. k
.times. .times. .pi. N .times. radians ( formula .times. .times. 51
) ##EQU00030##
[0578] where k=0, 1, 2, . . . , N-2, N-1. When N=5, 7, 9, 11, or
15, the reception device is able to obtain good data reception
quality.
[0579] Although the present description discusses the details of
phase changing methods involving two modulated signals transmitted
by a plurality of antennas, no limitation is intended in this
regard. Precoding and a change of phase may be performed on three
or more baseband signals on which mapping has been performed
according to a modulation method, followed by predetermined
processing on the post-phase change baseband signals and
transmission using a plurality of antennas, to realize the same
results.
[0580] Programs for executing the above transmission method may,
for example, be stored in advance in ROM (Read-Only Memory) and be
read out for operation by a CPU.
[0581] Furthermore, the programs for executing the above
transmission method may be stored on a computer-readable recording
medium, the programs stored in the recording medium may be loaded
in the RAM (Random Access Memory) of the computer, and the computer
may be operated in accordance with the programs.
[0582] The components of the above-described Embodiments may be
typically assembled as an LSI (Large Scale Integration), a type of
integrated circuit. Individual components may respectively be made
into discrete chips, or a subset or entirety of the components may
be made into a single chip. Although an LSI is mentioned above, the
terms IC (Integrated Circuit), system LSI, super LSI, or ultra LSI
may also apply, depending on the degree of integration.
Furthermore, the method of integrated circuit assembly is not
limited to LSI. A dedicated circuit or a general-purpose processor
may be used. After LSI assembly, a FPGA (Field Programmable Gate
Array) or reconfigurable processor may be used.
[0583] Furthermore, should progress in the field of semiconductors
or emerging technologies lead to replacement of LSI with other
integrated circuit methods, then such technology may of course be
used to integrate the functional blocks. Applications to
biotechnology are also plausible.
Embodiment C1
[0584] Embodiment 1 explained that the precoding matrix in use may
be switched when transmission parameters change. The present
Embodiment describes a detailed example of such a case, where, as
described above (in the supplement), the transmission parameters
change such that streams s1(t) and s2(t) switch between
transmitting different data and transmitting identical data, and
the precoding matrix and phase changing method being used are
switched accordingly.
[0585] The example of the present Embodiment describes a situation
where two modulated signals transmitted from two different transmit
antenna alternate between having the modulated signals include
identical data and having the modulated signals each include
different data.
[0586] FIG. 56 illustrates a sample configuration of a transmission
device switching between transmission methods, as described above.
In FIG. 56, components operating in the manner described for FIG.
54 use identical reference numbers. As shown, FIG. 56 differs from
FIG. 54 in that a distributor 404 takes the frame configuration
signal 313 as input. The operations of the distributor 404 are
described using FIG. 57.
[0587] FIG. 57 illustrates the operations of the distributor 404
when transmitting identical data and when transmitting different
data. As shown, given encoded data x1, x2, x3, x4, x5, x6, and so
on, when transmitting identical data, distributed data 405 is given
as x1, x2, x3, x4, x5, x6, and so on, while distributed data 405B
is similarly given as x1, x2, x3, x4, x5, x6, and so on.
[0588] On the other hand, when transmitting different data,
distributed data 405A are given as x1, x3, x5, x7, x9, and so on,
while distributed data 405B are given as x2, x4, x6, x8, x10, and
so on.
[0589] The distributor 404 determines, according to the frame
configuration signal 313 taken as input, whether the transmission
mode is identical data transmission or different data
transmission.
[0590] An alternative method to the above is shown in FIG. 58. As
shown, when transmitting identical data, the distributor 404
outputs distributed data 405A as x1, x2, x3, x4, x5, x6, and so on,
while outputting nothing as distributed data 405B. Accordingly,
when the frame configuration signal 313 indicates identical data
transmission, the distributor 404 operates as described above,
while interleaver 304B and mapper 306B from FIG. 56 do not operate.
Thus, only baseband signal 307A output by mapper 306A from FIG. 56
is valid, and is taken as input by both weighting unit 308A and
308B.
[0591] One characteristic feature of the present Embodiment is
that, when the transmission mode switches from identical data
transmission to different data transmission, the precoding matrix
may also be switched. As indicated by Math. 36 (formula 36) and
Math. 39 (formula 39) in Embodiment 1, given a matrix made up of
w11, w12, w21, and w22, the precoding matrix used to transmit
identical data may be as follows.
[ Math . .times. 52 ] ( w .times. .times. 11 w .times. .times. 12 w
.times. .times. 21 w .times. .times. 22 ) = ( a 0 0 a ) ( formula
.times. .times. 52 ) ##EQU00031##
[0592] where a is a real number (a may also be a complex number,
but given that the baseband signal input as a result of precoding
undergoes a change of phase, a real number is preferable for
considerations of circuit size and complexity reduction). Also,
when a is equal to one, the weighting units 308A and 308B do not
perform weighting and output the input signal as-is.
[0593] Accordingly, when transmitting identical data, the weighted
baseband signals 309A and 316B are identical signals output by the
weighting units 308A and 308B.
[0594] When the frame configuration signal 313 indicates identical
transmission mode, a phase changer 5201 performs a change of phase
on weighted baseband signal 309A and outputs post-phase change
baseband signal 5202. Similarly, when the frame configuration
signal indicates identical transmission mode, phase changer 317B
performs a change of phase on weighted baseband signal 316B and
outputs post-phase change baseband signal 309B. The change of phase
performed by phase changer 5201 is of e.sup.jA(t) (alternatively,
e.sup.jA(f) or e.sup.jA(t,f)) (where t is time and f is frequency)
(accordingly, e.sup.jA(t) (alternatively, e.sup.jA(f) or
e.sup.jA(t,f)) is the value by which the input baseband signal is
multiplied), and the change of phase performed by phase changer
317B is of e.sup.jB(t) (alternatively, e.sup.jB(f) or
e.sup.jB(t,f)) (where t is time and f is frequency) (accordingly,
e.sup.jB(t) (alternatively, e.sup.jB(f) or e.sup.jB(t,f)) is the
value by which the input baseband signal is multiplied). As such,
the following condition is satisfied.
[Math. 53]
[0595] Some time t satisfies
e.sup.jA(t).noteq.e.sup.jB(t)
[0596] (Or, some (carrier) frequency f satisfies
e.sup.jA(f).noteq.E.sup.jB(f))
[0597] (Or, some (carrier) frequency f and time t satisfy
e.sup.jA(t,f).noteq.e.sup.jb(t,f))
[0598] As such, the transmit signal is able to reduce multi-path
influence and thereby improve data reception quality for the
reception device. (However, the change of phase may also be
performed by only one of the weighted baseband signals 309A and
316B.)
[0599] In FIG. 56, when OFDM is used, processing such as IFFT and
frequency conversion is performed on post-phase change baseband
signal 5202, and the result is transmitted by a transmit antenna.
(See FIG. 13) (Accordingly, post-phase change baseband signal 5202
may be considered the same as signal 1301A from FIG. 13.)
Similarly, when OFDM is used, processing such as IFFT and frequency
conversion is performed on post-phase change baseband signal 309B,
and the result is transmitted by a transmit antenna. (See FIG. 13)
(Accordingly, post-phase change baseband signal 309B may be
considered the same as signal 1301B from FIG. 13.)
[0600] When the selected transmission mode indicates different data
transmission, then any of Math. 36 (formula 36), Math. 39 (formula
39), and Math. 50 (formula 50) given in Embodiment 1 may apply.
Significantly, the phase changers 5201 and 317B from FIG. 56 is a
different phase changing method than when transmitting identical
data. Specifically, as described in Embodiment 1, for example,
phase changer 5201 performs the change of phase while phase changer
317B does not, or phase changer 317B performs the change of phase
while phase changer 5201 does not. Only one of the two phase
changers performs the change of phase. As such, the reception
device obtains good data reception quality in the LOS environment
as well as the NLOS environment.
[0601] When the selected transmission mode indicates different data
transmission, the precoding matrix may be as given in Math. 52
(formula 52), or as given in any of Math. 36 (formula 36), Math. 50
(formula 50), and Math. 39 (formula 39), or may be a precoding
matrix unlike that given in Math. 52 (formula 52). Thus, the
reception device is especially likely to experience improvements to
data reception quality in the LOS environment.
[0602] Furthermore, although the present Embodiment discusses
examples using OFDM as the transmission method, the invention is
not limited in this manner. Multi-carrier methods other than OFDM
and single-carrier methods may all be used to achieve similar
Embodiments. Here, spread-spectrum communications may also be used.
When single-carrier methods are used, the change of phase is
performed with respect to the time domain.
[0603] As explained in Embodiment 3, when the transmission method
involves different data transmission, the change of phase is
carried out on the data symbols, only. However, as described in the
present Embodiment, when the transmission method involves identical
data transmission, then the change of phase need not be limited to
the data symbols but may also be performed on pilot symbols,
control symbols, and other such symbols inserted into the
transmission frame of the transmit signal. (The change of phase
need not always be performed on symbols such as pilot symbols and
control symbols, though doing so is preferable in order to achieve
diversity gain.)
Embodiment C2
[0604] The present Embodiment describes a configuration method for
a base station corresponding to Embodiment C1.
[0605] FIG. 59 illustrates the relationship of a base stations
(broadcasters) to terminals. A terminal P (5907) receives transmit
signal 5903A transmitted by antenna 5904A and transmit signal 5905A
transmitted by antenna 5906A of broadcaster A (5902A), then
performs predetermined processing thereon to obtained received
data.
[0606] A terminal Q (5908) receives transmit signal 5903A
transmitted by antenna 5904A of base station A (5902A) and transmit
signal 593B transmitted by antenna 5904B of base station B (5902B),
then performs predetermined processing thereon to obtained received
data.
[0607] FIGS. 60 and 61 illustrate the frequency allocation of base
station A (5902A) for transmit signals 5903A and 5905A transmitted
by antennas 5904A and 5906A, and the frequency allocation of base
station B (5902B) for transmit signals 5903B and 5905B transmitted
by antennas 5904B and 5906B. In FIGS. 60 and 61, frequency is on
the horizontal axis and transmission power is on the vertical
axis.
[0608] As shown, transmit signals 5903A and 5905A transmitted by
base station A (5902A) and transmit signals 5903B and 5905B
transmitted by base station B (5902B) use at least frequency band X
and frequency band Y. Frequency band X is used to transmit data of
a first channel, and frequency band Y is used to transmit data of a
second channel.
[0609] Accordingly, terminal P (5907) receives transmit signal
5903A transmitted by antenna 5904A and transmit signal 5905A
transmitted by antenna 5906A of base station A (5902A), extracts
frequency band X therefrom, performs predetermined processing, and
thus obtains the data of the first channel. Terminal Q (5908)
receives transmit signal 5903A transmitted by antenna 5904A of base
station A (5902A) and transmit signal 5903B transmitted by antenna
5904B of base station B (5902B), extracts frequency band Y
therefrom, performs predetermined processing, and thus obtains the
data of the second channel.
[0610] The following describes the configuration and operations of
base station A (5902A) and base station B (5902B).
[0611] As described in Embodiment C1, both base station A (5902A)
and base station B (5902B) incorporate a transmission device
configured as illustrated by FIGS. 56 and 13. When transmitting as
illustrated by FIG. 60, base station A (5902A) generates two
different modulated signals (on which precoding and a change of
phase are performed) with respect to frequency band X as described
in Embodiment C1. The two modulated signals are respectively
transmitted by the antennas 5904A and 5906A. With respect to
frequency band Y, base station A (5902A) operates interleaver 304A,
mapper 306A, weighting unit 308A, and phase changer from FIG. 56 to
generate modulated signal 5202. Then, a transmit signal
corresponding to modulated signal 5202 is transmitted by antenna
1310A from FIG. 13, i.e., by antenna 5904A from FIG. 59. Similarly,
base station B (5902B) operates interleaver 304A, mapper 306A,
weighting unit 308A, and phase changer 5201 from FIG. 56 to
generate modulated signal 5202. Then, a transmit signal
corresponding to modulated signal 5202 is transmitted by antenna
1310A from FIG. 13, i.e., by antenna 5904B from FIG. 59.
[0612] The creation of encoded data in frequency band Y may
involve, as shown in FIG. 56, generating encoded data in individual
base stations, or may involve having one of the base stations
generate such encoded data for transmission to other base stations.
As an alternative method, one of the base stations may generate
modulated signals and be configured to pass the modulated signals
so generated to other base stations.
[0613] Also, in FIG. 59, signal 5901 includes information
pertaining to the transmission mode (identical data transmission or
different data transmission). The base stations obtain this signal
and thereby switch between generation methods for the modulated
signals in each frequency band. Here, signal 5901 is indicated in
FIG. 59 as being input from another device or from a network.
However, configurations where, for example, base station A (5902)
is a master station passing a signal corresponding to signal 5901
to base station B (5902B) are also possible.
[0614] As explained above, when the base station transmits
different data, the precoding matrix and phase changing method are
set according to the transmission method to generate modulated
signals.
[0615] On the other hand, to transmit identical data, two base
stations respectively generate and transmit modulated signals. In
such circumstances, base stations each generating modulated signals
for transmission from a common antenna may be considered to be two
combined base stations using the precoding matrix given by Math. 52
(formula 52). The phase changing method is as explained in
Embodiment C1, for example, and satisfies the conditions of Math.
53 (formula 53).
[0616] In addition, the transmission method of frequency band X and
frequency band Y may vary over time. Accordingly, as illustrated in
FIG. 61, as time passes, the frequency allocation changes from that
indicated in FIG. 60 to that indicated in FIG. 61.
[0617] According to the present Embodiment, not only can the
reception device obtain improved data reception quality for
identical data transmission as well as different data transmission,
but the transmission devices can also share a phase changer.
[0618] Furthermore, although the present Embodiment discusses
examples using OFDM as the transmission method, the invention is
not limited in this manner. Multi-carrier methods other than OFDM
and single-carrier methods may all be used to achieve similar
Embodiments. Here, spread-spectrum communications may also be used.
When single-carrier methods are used, the change of phase is
performed with respect to the time domain.
[0619] As explained in Embodiment 3, when the transmission method
involves different data transmission, the change of phase is
carried out on the data symbols, only. However, as described in the
present Embodiment, when the transmission method involves identical
data transmission, then the change of phase need not be limited to
the data symbols but may also be performed on pilot symbols,
control symbols, and other such symbols inserted into the
transmission frame of the transmit signal. (The change of phase
need not always be performed on symbols such as pilot symbols and
control symbols, though doing so is preferable in order to achieve
diversity gain.)
Embodiment C3
[0620] The present Embodiment describes a configuration method for
a repeater corresponding to Embodiment C1. The repeater may also be
termed a repeating station.
[0621] FIG. 62 illustrates the relationship of a base stations
(broadcasters) to repeaters and terminals. As shown in FIG. 63,
base station 6201 at least transmits modulated signals on frequency
band X and frequency band Y. Base station 6201 transmits respective
modulated signals on antenna 6202A and antenna 6202B. The
transmission method here used is described later, with reference to
FIG. 63.
[0622] Repeater A (6203A) performs processing such as demodulation
on received signal 6205A received by receive antenna 6204A and on
received signal 6207A received by receive antenna 6206A, thus
obtaining received data. Then, in order to transmit the received
data to a terminal, repeater A (6203A) performs transmission
processing to generate modulated signals 6209A and 6211A for
transmission on respective antennas 6210A and 6212A.
[0623] Similarly, repeater B (6203B) performs processing such as
demodulation on received signal 6205B received by receive antenna
6204B and on received signal 6207B received by receive antenna
6206B, thus obtaining received data. Then, in order to transmit the
received data to a terminal, repeater B (6203B) performs
transmission processing to generate modulated signals 6209B and
6211B for transmission on respective antennas 6210B and 6212B.
Here, repeater B (6203B) is a master repeater that outputs a
control signal 6208. repeater A (6203A) takes the control signal as
input. A master repeater is not strictly necessary. Base station
6201 may also transmit individual control signals to repeater A
(6203A) and to repeater B (6203B).
[0624] Terminal P (5907) receives modulated signals transmitted by
repeater A (6203A), thereby obtaining data. Terminal Q (5908)
receives signals transmitted by repeater A (6203A) and by repeater
B (6203B), thereby obtaining data. Terminal R (6213) receives
modulated signals transmitted by repeater B (6203B), thereby
obtaining data.
[0625] FIG. 63 illustrates the frequency allocation for a modulated
signal transmitted by antenna 6202A among transmit signals
transmitted by the base station, and the frequency allocation of
modulated signals transmitted by antenna 6202B. In FIG. 63,
frequency is on the horizontal axis and transmission power is on
the vertical axis.
[0626] As shown, the modulated signals transmitted by antenna 6202A
and by antenna 6202B use at least frequency band X and frequency
band Y. Frequency band X is used to transmit data of a first
channel, and frequency band Y is used to transmit data of a second
channel.
[0627] As described in Embodiment C1, the data of the first channel
is transmitted using frequency band X in different data
transmission mode. Accordingly, as shown in FIG. 63, the modulated
signals transmitted by antenna 6202A and by antenna 6202B include
components of frequency band X. These components of frequency band
X are received by repeater A and by repeater B. Accordingly, as
described in Embodiment 1 and in Embodiment C1, modulated signals
in frequency band X are signals on which mapping has been
performed, and to which precoding (weighting) and the change of
phase are applied.
[0628] As shown in FIG. 62, the data of the second channel is
transmitted by antenna 6202A of FIG. 2 and transmits data in
components of frequency band Y. These components of frequency band
Y are received by repeater A and by repeater B.
[0629] FIG. 64 illustrate the frequency allocation for transmit
signals transmitted by repeater A and repeater B, specifically for
modulated signal 6209A transmitted by antenna 6210A and modulated
signal 6211A transmitted by antenna 6212A of repeater 6210A, and
for modulated signal 6209B transmitted by antenna 6210B and
modulated signal 6211B transmitted by antenna 6212B of repeater B.
In FIG. 64, frequency is on the horizontal axis and transmission
power is on the vertical axis.
[0630] As shown, modulated signal 6209A transmitted by antenna
6210A and modulated signal 6211A transmitted by antenna 6212A use
at least frequency band X and frequency band Y. Also, modulated
signal 6209B transmitted by antenna 6210B and modulated signal
6211B transmitted by antenna 6212B similarly use at least frequency
band X and frequency band Y. Frequency band X is used to transmit
data of a first channel, and frequency band Y is used to transmit
data of a second channel.
[0631] As described in Embodiment C1, the data of the first channel
is transmitted using frequency band X in different data
transmission mode. Accordingly, as shown in FIG. 64, modulated
signal 6209A transmitted by antenna 6210A and modulated signal
6211A transmitted by antenna 6212B include components of frequency
band X. These components of frequency band X are received by
terminal P. Similarly, as shown in FIG. 64, modulated signal 6209B
transmitted by antenna 6210B and modulated signal 6211B transmitted
by antenna 6212B include components of frequency band X. These
components of frequency band X are received by terminal R.
Accordingly, as described in Embodiment 1 and in Embodiment C1,
modulated signals in frequency band X are signals on which mapping
has been performed, and to which precoding (weighting) and the
change of phase are applied.
[0632] As shown in FIG. 64, the data of the second channel is
carried by the modulated signals transmitted by antenna 6210A of
repeater A (6203A) and by antenna 6210B of repeater B (6203) from
FIG. 62 and transmits data in components of frequency band Y. Here,
the components of frequency band Y in modulated signal 6209A
transmitted by antenna 6210A of repeater A (6203A) and those in
modulated signal 6209B transmitted by antenna 6210B of repeater B
(6203B) are used in a transmission mode that involves identical
data transmission, as explained in Embodiment C1. These components
of frequency band Y are received by terminal Q.
[0633] The following describes the configuration of repeater A
(6203A) and repeater B (6203B) from FIG. 62, with reference to FIG.
65.
[0634] FIG. 65 illustrates a sample configuration of a receiver and
transmitter in a repeater. Components operating identically to
those of FIG. 56 use the same reference numbers thereas. Receiver
6203X takes received signal 6502A received by receive antenna 6501A
and received signal 6502B received by receive antenna 6501B as
input, performs signal processing (signal demultiplexing or
compositing, error-correction decoding, and so on) on the
components of frequency band X thereof to obtain data 6204X
transmitted by the base station using frequency band X, outputs the
data to the distributor 404 and obtains transmission method
information included in control information (and transmission
method information when transmitted by a repeater), and outputs the
frame configuration signal 313.
[0635] Receiver 6203X and onward constitute a processor for
generating a modulated signal for transmitting frequency band X.
Further, the receiver here described is not only the receiver for
frequency band X as shown in FIG. 65, but also incorporates
receivers for other frequency bands. Each receiver forms a
processor for generating modulated signals for transmitting a
respective frequency band.
[0636] The overall operations of the distributor 404 are identical
to those of the distributor in the base station described in
Embodiment C2.
[0637] When transmitting as indicated in FIG. 64, repeater A
(6203A) and repeater B (6203B) generate two different modulated
signals (on which precoding and change of phase are performed) in
frequency band X as described in Embodiment C1. The two modulated
signals are respectively transmitted by antennas 6210A and 6212A of
repeater A (6203) from FIG. 62 and by antennas 6210B and 6212B of
repeater B (6203B) from FIG. 62.
[0638] As for frequency band Y, repeater A (6203A) operates a
processor 6500 pertaining to frequency band Y and corresponding to
the signal processor 6500 pertaining to frequency band X shown in
FIG. 65 (the signal processor 6500 is the signal processor
pertaining to frequency band X, but given that an identical signal
processor is incorporated for frequency band Y, this description
uses the same reference numbers), interleaver 304A, mapper 306A,
weighting unit 308A, and phase changer 5201 to generate modulated
signal 5202. A transmit signal corresponding to modulated signal
5202 is then transmitted by antenna 1301A from FIG. 13, that is, by
antenna 6210A from FIG. 62. Similarly, repeater B (6203_B) operates
interleaver 304A, mapper 306A, weighting unit 308A, and phase
changer 5201 from FIG. 62 pertaining to frequency band Y to
generate modulated signal 5202. Then, a transmit signal
corresponding to modulated signal 5202 is transmitted by antenna
1310A from FIG. 13, i.e., by antenna 6210B from FIG. 62.
[0639] As shown in FIG. 66 (FIG. 66 illustrates the frame
configuration of the modulated signal transmitted by the base
station, with time on the horizontal axis and frequency on the
vertical axis), the base station transmits transmission method
information 6601, repeater-applied phase change information 6602,
and data symbols 6603. The repeater obtains and applies the
transmission method information 6601, the repeater-applied phase
change information 6602, and the data symbols 6603 to the transmit
signal, thus determining the phase changing method. When the
repeater-applied phase change information 6602 from FIG. 66 is not
included in the signal transmitted by the base station, then as
shown in FIG. 62, repeater B (6203B) is the master and indicates
the phase changing method to repeater A (6203A).
[0640] As explained above, when the repeater transmits different
data, the precoding matrix and phase changing method are set
according to the transmission method to generate modulated
signals.
[0641] On the other hand, to transmit identical data, two repeaters
respectively generate and transmit modulated signals. In such
circumstances, repeaters each generating modulated signals for
transmission from a common antenna may be considered to be two
combined repeaters using the precoding matrix given by Math. 52
(formula 52). The phase changing method is as explained in
Embodiment C1, for example, and satisfies the conditions of Math.
53 (formula 53).
[0642] Also, as explained in Embodiment C1 for frequency band X,
the base station and repeater may each have two antennas that
transmit respective modulated signals and two antennas that receive
identical data. The operations of such a base station or repeater
are as described for Embodiment C1.
[0643] According to the present Embodiment, not only can the
reception device obtain improved data reception quality for
identical data transmission as well as different data transmission,
but the transmission devices can also share a phase changer.
[0644] Furthermore, although the present Embodiment discusses
examples using OFDM as the transmission method, the invention is
not limited in this manner. Multi-carrier methods other than OFDM
and single-carrier methods may all be used to achieve similar
Embodiments. Here, spread-spectrum communications may also be used.
When single-carrier methods are used, the change of phase is
performed with respect to the time domain.
[0645] As explained in Embodiment 3, when the transmission method
involves different data transmission, the change of phase is
carried out on the data symbols, only. However, as described in the
present Embodiment, when the transmission method involves identical
data transmission, then the change of phase need not be limited to
the data symbols but may also be performed on pilot symbols,
control symbols, and other such symbols inserted into the
transmission frame of the transmit signal. (The change of phase
need not always be performed on symbols such as pilot symbols and
control symbols, though doing so is preferable in order to achieve
diversity gain.)
Embodiment C4
[0646] The present Embodiment concerns a phase changing method
different from the phase changing methods described in Embodiment 1
and in the Supplement.
[0647] In Embodiment 1, Math. 36 (formula 36) is given as an
example of a precoding matrix, and in the Supplement, Math. 50
(formula 50) is similarly given as another such example. In
Embodiment A1, the phase changers from FIGS. 3, 4, 6, 12, 25, 29,
51, and 53 are indicated as having a phase changing value of
PHASE[i] (where i=0, 1, 2, . . . , N-2, N-1) to achieve a period
(cycle) of N (value reached given that FIGS. 3, 4, 6, 12, 25, 29,
51, and 53 perform a change of phase on only one baseband signal).
The present description discusses performing a change of phase on
one precoded baseband signal (i.e., in FIGS. 3, 4, 6, 12, 25, 29,
51 and 53) namely on precoded baseband signal z2'. Here, PHASE[k]
is calculated as follows.
[ Math . .times. 54 ] PHASE .times. [ k ] = 2 .times. .times. k
.times. .times. .pi. N .times. .times. radians ( formula .times.
.times. 54 ) where .times. .times. k = 0 , 1 , 2 , .times. , N - 2
, N - 1. ##EQU00032##
[0648] Accordingly, the reception device is able to achieve
improvements in data reception quality in the LOS environment, and
especially in a radio wave propagation environment. In the LOS
environment, when the change of phase has not been performed, a
regular phase relationship occurs. However, when the change of
phase is performed, the phase relationship is modified, in turn
avoiding poor conditions in a burst-like propagation environment.
As an alternative to Math. 54 (formula 54), PHASE[k] may be
calculated as follows.
[ Math . .times. 55 ] PHASE .times. [ k ] = - k .times. .times.
.pi. N .times. .times. radians ( formula .times. .times. 55 ) where
.times. .times. k = 0 , 1 , 2 , .times. , N - 2 , N - 1.
##EQU00033##
[0649] As a further alternative phase changing method, PHASE[k] may
be calculated as follows.
[ Math . .times. 56 ] PHASE .times. [ k ] = k .times. .times. .pi.
N + Z .times. .times. radians ( formula .times. .times. 56 ) where
.times. .times. k = 0 , 1 , 2 , .times. , N - 2 , N - 1.
##EQU00034##
[0650] As a further alternative phase changing method, PHASE[k] may
be calculated as follows.
[ Math . .times. 57 ] ##EQU00035## PHASE .function. [ k ] = - k
.times. .times. .pi. N + Z .times. .times. radians .times. .times.
where .times. .times. k = 0 , 1 , 2 , .times. , N - 2 , N - 1. (
formula .times. .times. 57 ) ##EQU00035.2##
[0651] As such, by performing the change of phase according to the
present Embodiment, the reception device is made more likely to
obtain good reception quality.
[0652] The change of phase of the present Embodiment is applicable
not only to single-carrier methods but also to multi-carrier
methods. Accordingly, the present Embodiment may also be realized
using, for example, spread-spectrum communications, OFDM, SC-FDMA,
SC-OFDM, wavelet OFDM as described in Non-Patent Literature 7, and
so on. As previously described, while the present Embodiment
explains the change of phase as a change of phase with respect to
the time domain t, the phase may alternatively be changed with
respect to the frequency domain as described in Embodiment 1. That
is, considering the change of phase with respect to the time domain
t described in the present Embodiment and replacing t with f (f
being the ((sub-) carrier) frequency) leads to a change of phase
applicable to the frequency domain. Also, as explained above for
Embodiment 1, the phase changing method of the present Embodiment
is also applicable to a change of phase with respect to both the
time domain and the frequency domain. Further, when the phase
changing method described in the present Embodiment satisfies the
conditions indicated in Embodiment A1, the reception device is
highly likely to obtain good data quality.
Embodiment C5
[0653] The present Embodiment concerns a phase changing method
different from the phase changing methods described in Embodiment
1, in the Supplement, and in Embodiment C4.
[0654] In Embodiment 1, Math. 36 (formula 36) is given as an
example of a precoding matrix, and in the Supplement, Math. 50
(formula 50) is similarly given as another such example. In
Embodiment A1, the phase changers from FIGS. 3, 4, 6, 12, 25, 29,
51, and 53 are indicated as having a phase changing value of
PHASE[i] (where i=0, 1, 2, . . . , N-2, N-1) to achieve a period
(cycle) of N (value reached given that FIGS. 3, 4, 6, 12, 25, 29,
51, and 53 perform a change of phase on only one baseband signal).
The present description discusses performing a change of phase on
one precoded baseband signal (i.e., in FIGS. 3, 4, 6, 12, 25, 29,
51 and 53) namely on precoded baseband signal z2'.
[0655] The characteristic feature of the phase changing method
pertaining to the present Embodiment is the period (cycle) of
N=2n+1. To achieve the period (cycle) of N=2n+1, n+1 different
phase changing values must be prepared. Among these n+1 different
phase changing values, n phase changing values are used twice per
period (cycle), and one phase changing value is used only once per
period (cycle), thus achieving the period (cycle) of N=2n+1. The
following describes these phase changing values in detail.
[0656] The n+1 different phase changing values required to achieve
a phase changing method in which the phase changing value is
regularly switched in a period (cycle) of N=2n+1 are expressed as
PHASE[0], PHASE[1], PHASE[i] PHASE[n-1], PHASE[n] (where i=0, 1, 2
. . . n-2, n-1, n). Here, the n+1 different phase changing values
of PHASE[0], PHASE[1], PHASE[i] PHASE[n-1], PHASE[n] are expressed
as follows.
[ Math . .times. 58 ] ##EQU00036## PHASE .function. [ k ] = 2
.times. k .times. .times. .pi. 2 .times. n + 1 .times. .times.
radians ( formula .times. .times. 58 ) ##EQU00036.2##
[0657] where k=0, 1, 2, . . . , n-2, n-1, n. The n+1 different
phase changing values PHASE[0], PHASE[1] . . . PHASE[i] . . .
PHASE[n-1], PHASE[n] are given by Math. 58 (formula 58). PHASE[0]
is used once, while PHASE[1] through PHASE[n] are each used twice
(i.e., PHASE[1] is used twice, PHASE[2] is used twice, and so on,
until PHASE[n-1] is used twice and PHASE[n] is used twice). As
such, through this phase changing method in which the phase
changing value is regularly switched in a period (cycle) of N=2n+1,
a phase changing method is realized in which the phase changing
value is regularly switched between fewer phase changing values.
Thus, the reception device is able to achieve better data reception
quality. As the phase changing values are smaller, the effect
thereof on the transmission device and reception device may be
reduced. According to the above, the reception device is able to
achieve improvements in data reception quality in the LOS
environment, and especially in a radio wave propagation
environment. In the LOS environment, when the change of phase has
not been performed, a regular phase relationship occurs. However,
when the change of phase is performed, the phase relationship is
modified, in turn avoiding poor conditions in a burst-like
propagation environment. As an alternative to Math. 58 (formula
58), PHASE[k] may be calculated as follows.
[ Math . .times. 59 ] ##EQU00037## PHASE .function. [ k ] = - 2
.times. k .times. .times. .pi. 2 .times. n + 1 .times. .times.
radians .times. .times. where .times. .times. k = 0 , 1 , 2 ,
.times. , n - 2 , n - 1 , n . ( formula .times. .times. 59 )
##EQU00037.2##
[0658] The n+1 different phase changing values PHASE[0], PHASE[1] .
. . PHASE[i] . . . PHASE[n-1], PHASE[n] are given by Math. 59
(formula 59). PHASE[0] is used once, while PHASE[1] through
PHASE[n] are each used twice (i.e., PHASE[1] is used twice,
PHASE[2] is used twice, and so on, until PHASE[n-1] is used twice
and PHASE[n] is used twice). As such, through this phase changing
method in which the phase changing value is regularly switched in a
period (cycle) of N=2n+1, a phase changing method is realized in
which the phase changing value is regularly switched between fewer
phase changing values. Thus, the reception device is able to
achieve better data reception quality. As the phase changing values
are smaller, the effect thereof on the transmission device and
reception device may be reduced.
[0659] As a further alternative, PHASE[k] may be calculated as
follows.
[ Math . .times. 60 ] ##EQU00038## PHASE .function. [ k ] = 2
.times. k .times. .times. .pi. 2 .times. n + 1 + Z .times. .times.
radians .times. .times. where .times. .times. k = 0 , 1 , 2 ,
.times. , N - 2 , N - 1. ( formula .times. .times. 60 )
##EQU00038.2##
[0660] The n+1 different phase changing values PHASE[0], PHASE[1] .
. . PHASE[i] . . . PHASE[n-1], PHASE[n] are given by Math. 60
(formula 60). PHASE[0] is used once, while PHASE[1] through
PHASE[n] are each used twice (i.e., PHASE[1] is used twice,
PHASE[2] is used twice, and so on, until PHASE[n-1] is used twice
and PHASE[n] is used twice). As such, through this phase changing
method in which the phase changing value is regularly switched in a
period (cycle) of N=2n+1, a phase changing method is realized in
which the phase changing value is regularly switched between fewer
phase changing values. Thus, the reception device is able to
achieve better data reception quality. As the phase changing values
are smaller, the effect thereof on the transmission device and
reception device may be reduced.
[0661] As a further alternative, PHASE[k] may be calculated as
follows.
[ Math . .times. 61 ] ##EQU00039## PHASE .function. [ k ] = - 2
.times. k .times. .times. .pi. 2 .times. n + 1 + Z .times. .times.
radians .times. .times. where .times. .times. k = 0 , 1 , 2 ,
.times. , n - 2 , n - 1 , n . ( formula .times. .times. 61 )
##EQU00039.2##
[0662] The n+1 different phase changing values PHASE[0], PHASE[1] .
. . PHASE[i] . . . PHASE[n-1], PHASE[n] are given by Math. 61
(formula 61). PHASE[0] is used once, while PHASE[1] through
PHASE[n] are each used twice (i.e., PHASE[1] is used twice,
PHASE[2] is used twice, and so on, until PHASE[n-1] is used twice
and PHASE[n] is used twice). As such, through this phase changing
method in which the phase changing value is regularly switched in a
period (cycle) of N=2n+1, a phase changing method is realized in
which the phase changing value is regularly switched between fewer
phase changing values. Thus, the reception device is able to
achieve better data reception quality. As the phase changing values
are smaller, the effect thereof on the transmission device and
reception device may be reduced.
[0663] As such, by performing the change of phase according to the
present Embodiment, the reception device is made more likely to
obtain good reception quality.
[0664] The change of phase of the present Embodiment is applicable
not only to single-carrier methods but also to transmission using
multi-carrier methods. Accordingly, the present Embodiment may also
be realized using, for example, spread-spectrum communications,
OFDM, SC-FDMA, SC-OFDM, wavelet OFDM as described in Non-Patent
Literature 7, and so on. As previously described, while the present
Embodiment explains the change of phase as a change of phase with
respect to the time domain t, the phase may alternatively be
changed with respect to the frequency domain as described in
Embodiment 1. That is, considering the change of phase with respect
to the time domain t described in the present Embodiment and
replacing t with f (f being the ((sub-) carrier) frequency) leads
to a change of phase applicable to the frequency domain. Also, as
explained above for Embodiment 1, the phase changing method of the
present Embodiment is also applicable to a change of phase with
respect to both the time domain and the frequency domain.
Embodiment C6
[0665] The present Embodiment describes a method of regularly
changing the phase, specifically that of Embodiment C5, when
encoding is performed using block codes as described in Non-Patent
Literature 12 through 15, such as QC LDPC Codes (not only QC-LDPC
but also LDPC codes may be used), concatenated LDPC (blocks) and
BCH codes, Turbo codes or Duo-Binary Turbo Codes using tail-biting,
and so on. The following example considers a case where two streams
s1 and s2 are transmitted. When encoding has been performed using
block codes and control information and the like is not necessary,
the number of bits making up each encoded block matches the number
of bits making up each block code (control information and so on
described below may yet be included). When encoding has been
performed using block codes or the like and control information or
the like (e.g., CRC transmission parameters) is required, then the
number of bits making up each encoded block is the sum of the
number of bits making up the block codes and the number of bits
making up the information.
[0666] FIG. 34 illustrates the varying numbers of symbols and slots
needed in each encoded block when block codes are used. FIG. 34
illustrates the varying numbers of symbols and slots needed in each
encoded block when block codes are used when, for example, two
streams s1 and s2 are transmitted as indicated by the transmission
device from FIG. 4, and the transmission device has only one
encoder. (Here, the transmission method may be any single-carrier
method or multi-carrier method such as OFDM.)
[0667] As shown in FIG. 34, when block codes are used, there are
6000 bits making up a single encoded block. In order to transmit
these 6000 bits, the number of required symbols depends on the
modulation method, being 3000 for QPSK, 1500 for 16-QAM, and 1000
for 64-QAM.
[0668] Then, given that the transmission device from FIG. 4
transmits two streams simultaneously, 1500 of the aforementioned
3000 symbols needed when the modulation method is QPSK are assigned
to s1 and the other 1500 symbols are assigned to s2. As such, 1500
slots for transmitting the 1500 symbols (hereinafter, slots) are
required for each of s1 and s2.
[0669] By the same reasoning, when the modulation method is 16-QAM,
750 slots are needed to transmit all of the bits making up each
encoded block, and when the modulation method is 64-QAM, 500 slots
are needed to transmit all of the bits making up each encoded
block.
[0670] The following describes the relationship between the
above-defined slots and the phase, as pertains to methods for a
regular change of phase.
[0671] Here, five different phase changing values (or phase
changing sets) are assumed as having been prepared for use in the
method for a regular change of phase, which has a period (cycle) of
five. That is, the phase changer of the transmission device from
FIG. 4 uses five phase changing values (or phase changing sets) to
achieve the period (cycle) of five. However, as described in
Embodiment C5, three different phase changing values are present.
Accordingly, some of the five phase changing values needed for the
period (cycle) of five are identical. (As in FIG. 6, five phase
changing values are needed in order to perform a change of phase
having a period (cycle) of five on precoded baseband signal z2'
only. Also, as in FIG. 26, two phase changing values are needed for
each slot in order to perform the change of phase on both precoded
baseband signals z1' and z2'. These two phase changing values are
termed a phase changing set. Accordingly, five phase changing sets
should ideally be prepared in order to perform a change of phase
having a period (cycle) of five in such circumstances). The five
phase changing values (or phase changing sets) needed for the
period (cycle) of five are expressed as P[0], P[1], P[2], P[3], and
P[4].
[0672] The following describes the relationship between the
above-defined slots and the phase, as pertains to methods for a
regular change of phase.
[0673] For the above-described 1500 slots needed to transmit the
6000 bits making up a single encoded block when the modulation
method is QPSK, phase changing value P[0] is used on 300 slots,
phase changing value P[1] is used on 300 slots, phase changing
value P[2] is used on 300 slots, phase changing value P[3] is used
on 300 slots, and phase changing value P[4] is used on 300 slots.
This is due to the fact that any bias in phase changing value usage
causes great influence to be exerted by the more frequently used
phase changing value, and that the reception device is dependent on
such influence for data reception quality.
[0674] Similarly, for the above-described 1500 slots needed to
transmit the 6000 bits making up the pair of encoded blocks when
the modulation method is 16-QAM, phase changing value P[0] is used
on 150 slots, phase changing value P[1] is used on 150 slots, phase
changing value P[2] is used on 150 slots, phase changing value P[3]
is used on 150 slots, and phase changing value P[4] is used on 150
slots.
[0675] Further, for the above-described 500 slots needed to
transmit the 6000 bits making up a single encoded block when the
modulation method is 64-QAM, phase changing value P[0] is used on
100 slots, phase changing value P[1] is used on 100 slots, phase
changing value P[2] is used on 100 slots, phase changing value P[3]
is used on 100 slots, and phase changing value P[4] is used on 100
slots.
[0676] As described above, a phase changing method for regularly
varying the phase changing value as given in Embodiment C5 requires
the preparation of N=2n+1 phase changing values P[0], P[1] . . .
P[2n-1], P[2n] (where P[0], P[1] . . . P[2n-1], P[2n] are expressed
as PHASE[0], PHASE[1], PHASE[2] . . . PHASE[n-1], PHASE[n] (see
Embodiment C5)). As such, in order to transmit all of the bits
making up the encoded block, phase changing value P[0] is used on
K.sub.0 slots, phase changing value P[1] is used on K.sub.1 slots,
phase changing value P[i] is used on Ki slots (where i=0, 1, 2, . .
. , 2n-1, 2n), and phase changing value P[2n] is used on K.sub.2n
slots, such that Condition #C01 is met.
(Condition #C01)
[0677] K.sub.0=K.sub.1 . . . K.sub.i= . . . K.sub.2n. That is,
K.sub.a=K.sub.b (.A-inverted.a and .A-inverted.b where a, b,=0, 1,
2 . . . 2n-1, 2n (a, b being integers between 0 and 2n,
a.noteq.b).
[0678] A phase changing method for a regular change of phase
changing value as given in Embodiment C5 having a period (cycle) of
N=2n+1 requires the preparation of phase changing values PHASE[0],
PHASE[1], PHASE[2] . . . PHASE[n-1], PHASE[n]. As such, in order to
transmit all of the bits making up a single encoded block, phase
changing value PHASE[0] is used on Go slots, phase changing value
PHASE[1] is used on G.sub.1 slots, phase changing value PHASE[i] is
used on G.sub.i slots (where i=0, 1, 2, . . . , n-1, n), and phase
changing value PHASE[n] is used on G.sub.n slots, such that
Condition #C01 is met. Condition #C01 may be modified as
follows.
(Condition #C02)
[0679] 2.times.G.sub.0=G.sub.1 . . . =G.sub.i= . . . G.sub.n. That
is, 2.times.G.sub.0=G.sub.a (.A-inverted.a where a=1, 2 . . . n-1,
n (a being an integer between 1 and n).
[0680] Then, when a communication system that supports multiple
modulation methods selects one such supported method for use,
Condition #C01 (or Condition #C02) must be met for the supported
modulation method.
[0681] However, when multiple modulation methods are supported,
each such modulation method typically uses symbols transmitting a
different number of bits per symbols (though some may happen to use
the same number), Condition #C01 (or Condition #C02) may not be
satisfied for some modulation methods. In such a case, the
following condition applies instead of Condition #C01.
(Condition #C03)
[0682] The difference between K.sub.a and K.sub.b satisfies 0 or 1.
That is, |K.sub.a-K.sub.b| satisfies 0 or 1 (.A-inverted.a,
.A-inverted.b, where a, b=0, 1, 2 . . . 2n-1, 2n (a and b being
integers between 0 and 2n) a.noteq.b).
Alternatively, Condition #C03 may be expressed as follows.
(Condition #C04)
[0683] The difference between G.sub.a and G.sub.b satisfies 0, 1,
or 2. That is, |G.sub.a-G.sub.b| satisfies 0, 1, or 2
(.A-inverted.a, .A-inverted.b, where a, b=1, 2 . . . n-1, n (a and
b being integers between 1 and n) a.noteq.b) and
The difference between 2.times.G.sub.0 and G.sub.a satisfies 0, 1,
or 2. That is, |2.times.G.sub.0-G.sub.a| satisfies 0, 1, or 2
(.A-inverted.a, where a=1, 2 . . . n-1, n (a being an integer
between 1 and n)).
[0684] FIG. 35 illustrates the varying numbers of symbols and slots
needed in two coded blocks when block codes are used. FIG. 35
illustrates the varying numbers of symbols and slots needed in each
encoded block when block codes are used when, for example, two
streams s1 and s2 are transmitted as indicated by the transmission
device from FIG. 3 and FIG. 12, and the transmission device has two
encoders. (Here, the transmission method may be any single-carrier
method or multi-carrier method such as OFDM.)
[0685] As shown in FIG. 35, when block codes are used, there are
6000 bits making up a single encoded block. In order to transmit
these 6000 bits, the number of required symbols depends on the
modulation method, being 3000 for QPSK, 1500 for 16-QAM, and 1000
for 64-QAM.
[0686] The transmission device from FIG. 3 and the transmission
device from FIG. 12 each transmit two streams at once, and have two
encoders. As such, the two streams each transmit different code
blocks. Accordingly, when the modulation method is QPSK, two
encoded blocks drawn from s1 and s2 are transmitted within the same
interval, e.g., a first encoded block drawn from s1 is transmitted,
then a second encoded block drawn from s2 is transmitted. As such,
3000 slots are needed in order to transmit the first and second
encoded blocks.
[0687] By the same reasoning, when the modulation method is 16-QAM,
1500 slots are needed to transmit all of the bits making up two
encoded blocks, and when the modulation method is 64-QAM, 1000
slots are needed to transmit all of the bits making up the two
encoded blocks.
[0688] The following describes the relationship between the
above-defined slots and the phase, as pertains to methods for a
regular change of phase.
[0689] Here, five different phase changing values (or phase
changing sets) are assumed as having been prepared for use in the
method for a regular change of phase, which has a period (cycle) of
five. That is, the phase changer of the transmission device from
FIG. 4 uses five phase changing values (or phase changing sets) to
achieve the period (cycle) of five. However, as described in
Embodiment C5, three different phase changing values are present.
Accordingly, some of the five phase changing values needed for the
period (cycle) of five are identical. (As in FIG. 6, five phase
changing values are needed in order to perform a change of phase
having a period (cycle) of five on precoded baseband signal z2'
only. Also, as in FIG. 26, two phase changing values are needed for
each slot in order to perform the change of phase on both precoded
baseband signals z1' and z2'. These two phase changing values are
termed a phase changing set. Accordingly, five phase changing sets
should ideally be prepared in order to perform a change of phase
having a period (cycle) of five in such circumstances). The five
phase changing values (or phase changing sets) needed for the
period (cycle) of five are expressed as P[0], P[1], P[2], P[3], and
P[4].
[0690] For the above-described 3000 slots needed to transmit the
6000.times.2 bits making up the pair of encoded blocks when the
modulation method is QPSK, phase changing value P[0] is used on 600
slots, phase changing value P[1] is used on 600 slots, phase
changing value P[2] is used on 600 slots, phase changing value P[3]
is used on 6100 slots, and phase changing value P[4] is used on 600
slots. This is due to the fact that any bias in phase changing
value usage causes great influence to be exerted by the more
frequently used phase changing value, and that the reception device
is dependent on such influence for data reception quality.
[0691] Further, in order to transmit the first coded block, phase
changing value P[0] is used on slots 600 times, phase changing
value P[1] is used on slots 600 times, phase changing value P[2] is
used on slots 600 times, phase changing value P[3] is used on slots
600 times, and phase changing value PHASE[4] is used on slots 600
times. Furthermore, in order to transmit the second coded block,
phase changing value P[0] is used on slots 600 times, phase
changing value P[1] is used on slots 600 times, phase changing
value P[2] is used on slots 600 times, phase changing value P[3] is
used on slots 600 times, and phase changing value P[4] is used on
slots 600 times.
[0692] Similarly, for the above-described 1500 slots needed to
transmit the 6000.times.2 bits making up the pair of encoded blocks
when the modulation method is 16-QAM, phase changing value P[0] is
used on 300 slots, phase changing value P[1] is used on 300 slots,
phase changing value P[2] is used on 300 slots, phase changing
value P[3] is used on 300 slots, and phase changing value P[4] is
used on 300 slots.
[0693] Furthermore, in order to transmit the first coded block,
phase changing value P[0] is used on slots 300 times, phase
changing value P[1] is used on slots 300 times, phase changing
value P[2] is used on slots 300 times, phase changing value P[3] is
used on slots 300 times, and phase changing value P[4] is used on
slots 300 times. Furthermore, in order to transmit the second coded
block, phase changing value P[0] is used on slots 300 times, phase
changing value P[1] is used on slots 300 times, phase changing
value P[2] is used on slots 300 times, phase changing value P[3] is
used on slots 300 times, and phase changing value P[4] is used on
slots 300 times.
[0694] Similarly, for the above-described 1000 slots needed to
transmit the 6000.times.2 bits making up the pair of encoded blocks
when the modulation method is 64-QAM, phase changing value P[0] is
used on 200 slots, phase changing value P[1] is used on 200 slots,
phase changing value P[2] is used on 200 slots, phase changing
value P[3] is used on 200 slots, and phase changing value P[4] is
used on 200 slots.
[0695] Furthermore, in order to transmit the first coded block,
phase changing value P[0] is used on slots 200 times, phase
changing value P[1] is used on slots 200 times, phase changing
value P[2] is used on slots 200 times, phase changing value P[3] is
used on slots 200 times, and phase changing value P[4] is used on
slots 200 times. Furthermore, in order to transmit the second coded
block, phase changing value P[0] is used on slots 200 times, phase
changing value P[1] is used on slots 200 times, phase changing
value P[2] is used on slots 200 times, phase changing value P[3] is
used on slots 200 times, and phase changing value P[4] is used on
slots 200 times.
[0696] As described above, a phase changing method for regularly
varying the phase changing value as given in Embodiment C5 requires
the preparation of N=2n+1 phase changing values P[0], P[1] . . .
P[2n-1], P[2n] (where P[0], P[1] . . . P[2n-1], P[2n] are expressed
as PHASE[0], PHASE[1], PHASE[2] . . . PHASE[n-1], PHASE[n] (see
Embodiment C5)). As such, in order to transmit all of the bits
making up the two encoded blocks, phase changing value P[0] is used
on K.sub.0 slots, phase changing value P[1] is used on K.sub.1
slots, phase changing value P[i] is used on K.sub.i slots (where
i=0, 1, 2 . . . 2n-1, 2n), and phase changing value P[2n] is used
on K2n slots.
(Condition #C05)
[0697] K.sub.0=K.sub.1 . . . =K.sub.i= . . . K.sub.2n. That is,
K.sub.a=K.sub.b (.A-inverted.a and .A-inverted.b where a, b,=0, 1,
2 . . . 2n-1, 2n (a, b being integers between 0 and 2n, a.noteq.b).
In order to transmit all of the bits making up the first coded
block, phase changing value P[0] is used K0,1 times, phase changing
value P[1] is used K.sub.1,1 times, phase changing value P[i] is
used K.sub.i,1 (where i=0, 1, 2 . . . 2n-1, 2n), and phase changing
value P[2n] is used K.sub.2n,1 times.
(Condition #C06)
[0697] [0698] K.sub.0,1=K.sub.1,1 . . . =K.sub.i,1= . . .
K.sub.2n,1. That is, K.sub.a,1=K.sub.b,1 (.A-inverted.a and
.A-inverted.b where a, b,=0, 1, 2 . . . 2n-1, 2n (a, b being
integers between 0 and 2n, a.noteq.b). In order to transmit all of
the bits making up the second encoded block, phase changing value
P[0] is used K.sub.0,2 times, phase changing value P[1] is used
K1,2 times, phase changing value P[i] is used K.sub.i,2 (where i=0,
1, 2 . . . 2n-1, 2n), and phase changing value P[2n] is used K2n,2
times.
(Condition #C07)
[0698] [0699] K.sub.0,2=K.sub.1,2 . . . =K.sub.i,2= . . .
K.sub.2n,2. That is, K.sub.a,2=K.sub.b,2 (.A-inverted.a and
.A-inverted.b where a, b,=0, 1, 2 . . . 2n-1, 2n (a, b being
integers between 0 and 2n, a # b).
[0700] A phase changing method for regularly varying the phase
changing value as given in Embodiment C5 having a period (cycle) of
N=2n+1 requires the preparation of phase changing values PHASE[0],
PHASE[1], PHASE[2] . . . PHASE[n-1], PHASE[n]. As such, in order to
transmit all of the bits making up the two encoded blocks, phase
changing value PHASE[0] is used on Go slots, phase changing value
PHASE[1] is used on G.sub.1 slots, phase changing value PHASE[i] is
used on G.sub.i slots (where i=0, 1, 2 . . . n-1, n), and phase
changing value PHASE[n] is used on G.sub.n slots, such that
Condition #C05 is met.
(Condition #C08)
[0701] 2.times.G.sub.0=G.sub.1 . . . =G.sub.i= . . . G.sub.n. That
is, 2.times.G.sub.0=G.sub.a (.A-inverted.a where a=1, 2 . . . n-1,
n (a being an integer between 1 and n). In order to transmit all of
the bits making up the first encoded block, phase changing value
PHASE[0] is used G.sub.0,1 times, phase changing value PHASE[1] is
used G.sub.1,1 times, phase changing value PHASE[i] is used
G.sub.i,1 (where i=0, 1, 2 . . . n-1, n), and phase changing value
PHASE[n] is used G.sub.n,1 times.
(Condition #C09)
[0701] [0702] 2.times.G.sub.0,=G.sub.1,1 . . . =G.sub.i,1= . . .
G.sub.n,1. That is, 2.times.G.sub.0,1=G.sub.a,1 (.A-inverted.a
where a=1, 2 . . . n-1, n (a being an integer between 1 and n). In
order to transmit all of the bits making up the second coded block,
phase changing value PHASE[0] is used G.sub.0,2 times, phase
changing value PHASE[1] is used G1,2 times, phase changing value
PHASE[i] is used G.sub.i,2 (where i=0, 1, 2 . . . n-1, n), and
phase changing value PHASE[n] is used G.sub.n,1 times.
(Condition #C10)
[0702] [0703] 2.times.G.sub.0,2=G.sub.1,2 . . .
=G.sub.i,2=G.sub.n,2. That is, 2.times.G.sub.0,2=G.sub.a,2
(.A-inverted.a where a=1, 2 . . . n-1, n (a being an integer
between 1 and n).
[0704] Then, when a communication system that supports multiple
modulation methods selects one such supported method for use,
Condition #C05, Condition #C06, and Condition #C07 (or Condition
#C08, Condition #C09, and Condition #C10) must be met for the
supported modulation method.
[0705] However, when multiple modulation methods are supported,
each such modulation method typically uses symbols transmitting a
different number of bits per symbols (though some may happen to use
the same number), Condition #C05, Condition #C06, and Condition
#C07 (or Condition #C08, Condition #C09, and Condition #C10) may
not be satisfied for some modulation methods. In such a case, the
following conditions apply instead of Condition #C05, Condition
#C06, and Condition #C07.
(Condition #C11)
[0706] The difference between K.sub.a and K.sub.b satisfies 0 or 1.
That is, |K.sub.a-K.sub.b satisfies 0 or 1 (.A-inverted.a,
.A-inverted.b, where a, b=0, 1, 2 . . . 2n-1, 2n (a and b being
integers between 0 and 2n) a.noteq.b).
(Condition #C12)
[0706] [0707] The difference between K.sub.a,1 and K.sub.b,1
satisfies 0 or 1. That is, |K.sub.a,1-K.sub.b,1| satisfies 0 or 1
(.A-inverted.a, .A-inverted.b, where a, b=0, 1, 2 . . . 2n-1, 2n (a
and b being integers between 0 and 2n) a.noteq.b).
(Condition #C13)
[0707] [0708] The difference between K.sub.a,2 and K.sub.b,2
satisfies 0 or 1. That is, |K.sub.a,2-K.sub.b,2| satisfies 0 or 1
(.A-inverted.a, .A-inverted.b, where a, b=0, 1, 2 . . . 2n-1, 2n (a
and b being integers between 0 and 2n) a.noteq.b). [0709]
Alternatively, Condition #C11, Condition #C12, and Condition #C13
may be expressed as follows.
(Condition #C14)
[0709] [0710] The difference between G.sub.a and G.sub.b satisfies
0, 1, or 2. That is, |G.sub.a-G.sub.b| satisfies 0, 1, or 2
(.A-inverted.a, .A-inverted.b, where a, b=1, 2 . . . n-1, n (a and
b being integers between 1 and n) a.noteq.b) and [0711] The
difference between 2.times.G.sub.0 and G.sub.a satisfies 0, 1, or
2. That is, |2.times.G.sub.0-G.sub.a| satisfies 0, 1, or 2
(.A-inverted.a, where a=1, 2 . . . n-1, n (a being an integer
between 1 and n)).
(Condition #C15)
[0711] [0712] The difference between G.sub.a,1 and G.sub.b,1
satisfies 0, 1, or 2. That is, |G.sub.a,1-G.sub.b,1| satisfies 0,
1, or 2 (.A-inverted.a, .A-inverted.b, where a, b=1, 2 . . . n-1, n
(a and b being integers between 1 and n) a.noteq.b) and [0713] The
difference between 2.times.G.sub.0,1 and G.sub.a,1 satisfies 0, 1,
or 2. That is, |2.times.G.sub.0,1-G.sub.a,1| satisfies 0, 1, or 2
(.A-inverted.a, where a=1, 2 . . . n-1, n (a being an integer
between 1 and n))
(Condition #C16)
[0713] [0714] The difference between G.sub.a,2 and G.sub.b,2
satisfies 0, 1, or 2. That is, |G.sub.a,2 G.sub.b,2| satisfies 0,
1, or 2 (.A-inverted.a, .A-inverted.b, where a, b=1, 2 . . . n-1, n
(a and b being integers between 1 and n) a.noteq.b) and [0715] The
difference between 2.times.G.sub.0,2 and G.sub.a,2 satisfies 0, 1,
or 2. That is, |2.times.G.sub.0,2-G.sub.a,2| satisfies 0, 1, or 2
(.A-inverted.a, where a=1, 2 . . . n-1, n (a being an integer
between 1 and n))
[0716] As described above, bias among the phase changing values
being used to transmit the encoded blocks is removed by creating a
relationship between the encoded block and the phase changing
values. As such, data reception quality can be improved for the
reception device.
[0717] In the present Embodiment, N phase changing values (or phase
changing sets) are needed in order to perform a change of phase
having a period (cycle) of N with the method for a regular change
of phase. As such, N phase changing values (or phase changing sets)
P[0], P[1], P[2] . . . P[N-2], and P[N-1] are prepared.
[0718] However, schemes exist for ordering the phases in the stated
order with respect to the frequency domain. No limitation is
intended in this regard. The N phase changing values (or phase
changing sets) P[0], P[1], P[2] . . . P[N-2], and P[N-1] may also
change the phases of blocks in the time domain or in the
time-frequency domain to obtain a symbol arrangement as described
in Embodiment 1. Although the above examples discuss a phase
changing scheme with a period (cycle) of N, the same effects are
obtainable using N phase changing values (or phase changing sets)
at random. That is, the N phase changing values (or phase changing
sets) need not always have regular periodicity. As long as the
above-described conditions are satisfied, quality data reception
improvements are realizable for the reception device.
[0719] Furthermore, given the existence of modes for spatial
multiplexing MIMO methods, MIMO methods using a fixed precoding
matrix, space-time block coding methods, single-stream
transmission, and methods using a regular change of phase, the
transmission device (broadcaster, base station) may select any one
of these transmission methods.
[0720] As described in Non-Patent Literature 3, spatial
multiplexing MIMO methods involve transmitting signals s1 and s2,
which are mapped using a selected modulation method, on each of two
different antennas. MIMO methods using a fixed precoding matrix
involve performing precoding only (with no change in phase).
Further, space-time block coding methods are described in
Non-Patent Literature 9, 16, and 17. Single-stream transmission
methods involve transmitting signal s1, mapped with a selected
modulation method, from an antenna after performing predetermined
processing.
[0721] Schemes using multi-carrier transmission such as OFDM
involve a first carrier group made up of a plurality of carriers
and a second carrier group made up of a plurality of carriers
different from the first carrier group, and so on, such that
multi-carrier transmission is realized with a plurality of carrier
groups. For each carrier group, any of spatial multiplexing MIMO
schemes, MIMO schemes using a fixed precoding matrix, space-time
block coding schemes, single-stream transmission, and schemes using
a regular change of phase may be used. In particular, schemes using
a regular change of phase on a selected (sub-)carrier group are
preferably used to realize the present Embodiment.
[0722] When a change of phase by, for example, a phase changing
value for P[i] of X radians is performed on only one precoded
baseband signal, the phase changers of FIGS. 3, 4, 6, 12, 25, 29,
51, and 53 multiply precoded baseband signal z2' by e.sup.jX. Then,
when a change of phase by, for example, a phase changing set for
P[i] of X radians and Y radians is performed on both precoded
baseband signals, the phase changers from FIGS. 26, 27, 28, 52, and
54 multiply precoded baseband signal z2' by e.sup.jX and multiply
precoded baseband signal z1' by e.sup.jY.
Embodiment C7
[0723] The present Embodiment describes a method of regularly
changing the phase, specifically as done in Embodiment A1 and
Embodiment C6, when encoding is performed using block codes as
described in Non-Patent Literature 12 through 15, such as QC LDPC
Codes (not only QC-LDPC but also LDPC (block) codes may be used),
concatenated LDPC and BCH codes, Turbo codes or Duo-Binary Turbo
Codes, and so on. The following example considers a case where two
streams s1 and s2 are transmitted. When encoding has been performed
using block codes and control information and the like is not
necessary, the number of bits making up each encoded block matches
the number of bits making up each block code (control information
and so on described below may yet be included). When encoding has
been performed using block codes or the like and control
information or the like (e.g., CRC transmission parameters) is
required, then the number of bits making up each encoded block is
the sum of the number of bits making up the block codes and the
number of bits making up the information.
[0724] FIG. 34 illustrates the varying numbers of symbols and slots
needed in one coded block when block codes are used. FIG. 34
illustrates the varying numbers of symbols and slots needed in each
encoded block when block codes are used when, for example, two
streams s1 and s2 are transmitted as indicated by the transmission
device from FIG. 4, and the transmission device has only one
encoder. (Here, the transmission method may be any single-carrier
method or multi-carrier method such as OFDM.)
[0725] As shown in FIG. 34, when block codes are used, there are
6000 bits making up a single encoded block. In order to transmit
these 6000 bits, the number of required symbols depends on the
modulation method, being 3000 for QPSK, 1500 for 16-QAM, and 1000
for 64-QAM.
[0726] Then, given that the transmission device from FIG. 4
transmits two streams simultaneously, 1500 of the aforementioned
3000 symbols needed when the modulation method is QPSK are assigned
to s1 and the other 1500 symbols are assigned to s2. As such, 1500
slots for transmitting the 1500 symbols (hereinafter, slots) are
required for each of s1 and s2.
[0727] By the same reasoning, when the modulation method is 16-QAM,
750 slots are needed to transmit all of the bits making up two
encoded blocks, and when the modulation method is 64-QAM, 500 slots
are needed to transmit all of the bits making up the two encoded
blocks.
[0728] The following describes the relationship between the
above-defined slots and the phase, as pertains to methods for a
regular change of phase.
[0729] Here, five different phase changing values (or phase
changing sets) are assumed as having been prepared for use in the
method for a regular change of phase, which has a period (cycle) of
five. The phase changing values (or phase changing sets) prepared
in order to regularly change the phase with a period (cycle) of
five are P[0], P[1], P[2], P[3], and P[4]. However, P[0], P[1],
P[2], P[3], and P[4] should include at least two different phase
changing values (i.e., P[0], P[1], P[2], P[3], and P[4] may include
identical phase changing values). (As in FIG. 6, five phase
changing values are needed in order to perform a change of phase
having a period (cycle) of five on precoded baseband signal z2'
only. Also, as in FIG. 26, two phase changing values are needed for
each slot in order to perform the change of phase on both precoded
baseband signals z1' and z2'. These two phase changing values are
termed a phase changing set. Accordingly, five phase changing sets
should ideally be prepared in order to perform a change of phase
having a period (cycle) of five in such circumstances).
[0730] For the above-described 1500 slots needed to transmit the
6000 bits making up a single encoded block when the modulation
method is QPSK, phase changing value P[0] is used on 300 slots,
phase changing value P[1] is used on 300 slots, phase changing
value P[2] is used on 300 slots, phase changing value P[3] is used
on 300 slots, and phase changing value P[4] is used on 300 slots.
This is due to the fact that any bias in phase changing value usage
causes great influence to be exerted by the more frequently used
phase changing value, and that the reception device is dependent on
such influence for data reception quality.
[0731] Further, for the above-described 750 slots needed to
transmit the 6000 bits making up a single encoded block when the
modulation method is 16-QAM, phase changing value P[0] is used on
150 slots, phase changing value P[1] is used on 150 slots, phase
changing value P[2] is used on 150 slots, phase changing value P[3]
is used on 150 slots, and phase changing value P[4] is used on 150
slots.
[0732] Further, for the above-described 500 slots needed to
transmit the 6000 bits making up a single encoded block when the
modulation method is 64-QAM, phase changing value P[0] is used on
100 slots, phase changing value P[1] is used on 100 slots, phase
changing value P[2] is used on 100 slots, phase changing value P[3]
is used on 100 slots, and phase changing value P[4] is used on 100
slots.
[0733] As described above, the phase changing values used in the
phase changing method regularly switching between phase changing
values with a period (cycle) of N are expressed as P[0], P[1] . . .
P[N-2], P[N-1]. However, P[0], P[1] . . . P[N-2], P[N-1] should
include at least two different phase changing values (i.e., P[0],
P[1] . . . P[N-2], P[N-1] may include identical phase changing
values). In order to transmit all of the bits making up a single
coded block, phase changing value P[0] is used on K.sub.0 slots,
phase changing value P[1] is used on K.sub.1 slots, phase changing
value P[i] is used on K.sub.i slots (where i=0, 1, 2 . . . N-1),
and phase changing value P[N-1] is used on K.sub.N-1 slots, such
that Condition #C17 is met.
(Condition #C17)
[0734] K.sub.0=K.sub.1 . . . =K.sub.i= . . . K.sub.N-1. That is,
K.sub.a=K.sub.b (.A-inverted.a and .A-inverted.b where a, b,=0, 1,
2 . . . N-1 (a and b being integers between zero and N-1)
a.noteq.b).
[0735] Then, when a communication system that supports multiple
modulation methods selects one such supported method for use,
Condition #C17 must be met for the supported modulation method.
[0736] However, when multiple modulation methods are supported,
each such modulation method typically uses symbols transmitting a
different number of bits per symbols (though some may happen to use
the same number), Condition #C17 may not be satisfied for some
modulation methods. In such a case, the following condition applies
instead of Condition #C17.
(Condition #C18)
[0737] The difference between K.sub.a and K.sub.b satisfies 0 or 1.
That is, |K.sub.a|K.sub.b| satisfies 0 or 1 (.A-inverted.a,
.A-inverted.b, where a, b=0, 1, 2 . . . N-1 (a and b being integers
between 0 and 2n) a.noteq.b).
[0738] FIG. 35 illustrates the varying numbers of symbols and slots
needed in two coded blocks when block codes are used. FIG. 35
illustrates the varying numbers of symbols and slots needed in each
encoded block when block codes are used when, for example, two
streams s1 and s2 are transmitted as indicated by the transmission
device from FIG. 3 and FIG. 12, and the transmission device has two
encoders. (Here, the transmission method may be any single-carrier
method or multi-carrier method such as OFDM.)
[0739] As shown in FIG. 35, when block codes are used, there are
6000 bits making up a single encoded block. In order to transmit
these 6000 bits, the number of required symbols depends on the
modulation method, being 3000 for QPSK, 1500 for 16-QAM, and 1000
for 64-QAM.
[0740] The transmission device from FIG. 3 and the transmission
device from FIG. 12 each transmit two streams at once, and have two
encoders. As such, the two streams each transmit different code
blocks. Accordingly, when the modulation method is QPSK, two
encoded blocks drawn from s1 and s2 are transmitted within the same
interval, e.g., a first encoded block drawn from s1 is transmitted,
then a second encoded block drawn from s2 is transmitted. As such,
3000 slots are needed in order to transmit the first and second
encoded blocks.
[0741] By the same reasoning, when the modulation method is 16-QAM,
1500 slots are needed to transmit all of the bits making up two
encoded blocks, and when the modulation method is 64-QAM, 1000
slots are needed to transmit all of the bits making up the two
encoded blocks.
[0742] The following describes the relationship between the
above-defined slots and the phase, as pertains to methods for a
regular change of phase.
[0743] Here, five different phase changing values (or phase
changing sets) are assumed as having been prepared for use in the
method for a regular change of phase, which has a period (cycle) of
five. That is, the phase changer of the transmission device from
FIG. 4 uses five phase changing values (or phase changing sets)
P[0], P[1], P[2], P[3], and P[4] to achieve the period (cycle) of
five. However, P[0], P[1], P[2], P[3], and P[4] should include at
least two different phase changing values (i.e., P[0], P[1], P[2],
P[3], and P[4] may include identical phase changing values). (As in
FIG. 6, five phase changing values are needed in order to perform a
change of phase having a period (cycle) of five on precoded
baseband signal z2' only. Also, as in FIG. 26, two phase changing
values are needed for each slot in order to perform the change of
phase on both precoded baseband signals z1' and z2'. These two
phase changing values are termed a phase changing set. Accordingly,
five phase changing sets should ideally be prepared in order to
perform a change of phase having a period (cycle) of five in such
circumstances). The five phase changing values (or phase changing
sets) needed for the period (cycle) of five are expressed as P[0],
P[1], P[2], P[3], and P[4].
[0744] For the above-described 3000 slots needed to transmit the
6000.times.2 bits making up the pair of encoded blocks when the
modulation method is QPSK, phase changing value P[0] is used on 600
slots, phase changing value P[1] is used on 600 slots, phase
changing value P[2] is used on 600 slots, phase changing value P[3]
is used on 600 slots, and phase changing value P[4] is used on 600
slots. This is due to the fact that any bias in phase changing
value usage causes great influence to be exerted by the more
frequently used phase changing value, and that the reception device
is dependent on such influence for data reception quality.
[0745] Further, in order to transmit the first coded block, phase
changing value P[0] is used on slots 600 times, phase changing
value P[1] is used on slots 600 times, phase changing value P[2] is
used on slots 600 times, phase changing value P[3] is used on slots
600 times, and phase changing value PHASE[4] is used on slots 600
times. Furthermore, in order to transmit the second coded block,
phase changing value P[0] is used on slots 600 times, phase
changing value P[1] is used on slots 600 times, phase changing
value P[2] is used on slots 600 times, phase changing value P[3] is
used on slots 600 times, and phase changing value P[4] is used on
slots 600 times.
[0746] Similarly, for the above-described 1500 slots needed to
transmit the 6000.times.2 bits making up the pair of encoded blocks
when the modulation method is 16-QAM, phase changing value P[0] is
used on 300 slots, phase changing value P[1] is used on 300 slots,
phase changing value P[2] is used on 300 slots, phase changing
value P[3] is used on 300 slots, and phase changing value P[4] is
used on 300 slots.
[0747] Furthermore, in order to transmit the first coded block,
phase changing value P[0] is used on slots 300 times, phase
changing value P[1] is used on slots 300 times, phase changing
value P[2] is used on slots 300 times, phase changing value P[3] is
used on slots 300 times, and phase changing value P[4] is used on
slots 300 times. Furthermore, in order to transmit the second coded
block, phase changing value P[0] is used on slots 300 times, phase
changing value P[1] is used on slots 300 times, phase changing
value P[2] is used on slots 300 times, phase changing value P[3] is
used on slots 300 times, and phase changing value P[4] is used on
slots 300 times.
[0748] Furthermore, for the above-described 1000 slots needed to
transmit the 6000.times.2 bits making up the two encoded blocks
when the modulation method is 64-QAM, phase changing value P[0] is
used on 200 slots, phase changing value P[1] is used on 200 slots,
phase changing value P[2] is used on 200 slots, phase changing
value P[3] is used on 200 slots, and phase changing value P[4] is
used on 200 slots.
[0749] Furthermore, in order to transmit the first coded block,
phase changing value P[0] is used on slots 200 times, phase
changing value P[1] is used on slots 200 times, phase changing
value P[2] is used on slots 200 times, phase changing value P[3] is
used on slots 200 times, and phase changing value P[4] is used on
slots 200 times. Furthermore, in order to transmit the second coded
block, phase changing value P[0] is used on slots 200 times, phase
changing value P[1] is used on slots 200 times, phase changing
value P[2] is used on slots 200 times, phase changing value P[3] is
used on slots 200 times, and phase changing value P[4] is used on
slots 200 times.
[0750] As described above, the phase changing values used in the
phase changing method regularly switching between phase changing
values with a period (cycle) of N are expressed as P[0], P[1] . . .
P[N-2], P[N-1]. However, P[0], P[1] . . . P[N-2], P[N-1] should
include at least two different phase changing values (i.e., P[0],
P[1] . . . P[N-2], P[N-1] may include identical phase changing
values). In order to transmit all of the bits making up a single
coded block, phase changing value P[0] is used on K.sub.0 slots,
phase changing value P[1] is used on K.sub.1 slots, phase changing
value P[i] is used on K.sub.i slots (where i=0, 1, 2 . . . N-1),
and phase changing value P[N-1] is used on K.sub.N-1 slots, such
that Condition #C19 is met.
(Condition #C19)
[0751] K.sub.0=K.sub.1 . . . =K.sub.i= . . . K.sub.N-1. That is,
K.sub.a=K.sub.b (.A-inverted.a and .A-inverted.b where a, b,=0, 1,
2 . . . N-1 (a and b being integers between zero and N-1)
a.noteq.b). [0752] In order to transmit all of the bits making up
the first coded block, phase changing value P[0] is used K.sub.0,1
times, phase changing value P[1] is used K.sub.1,1 times, phase
changing value P[i] is used K.sub.i,1 (where i=0, 1, 2 . . . N-1),
and phase changing value P[N-1] is used KN-1,1 times.
(Condition #C20)
[0752] [0753] K.sub.0,1=K.sub.1,1= . . . K.sub.i,1= . . .
K.sub.N-1,1. That is, K.sub.a,1=K.sub.b,1 (.A-inverted.a and
.A-inverted.b where a, b,=0, 1, 2 . . . N-1, a.noteq.b). [0754] In
order to transmit all of the bits making up the second coded block,
phase changing value P[0] is used K.sub.0,2 times, phase changing
value P[1] is used K.sub.1,2 times, phase changing value P[i] is
used K.sub.i,2 (where i=0, 1, 2 . . . N-1), and phase changing
value P[N-1] is used K.sub.N-1,2 times.
(Condition #C21)
[0754] [0755] K.sub.0,2=K.sub.1,2= . . . K.sub.i,2= . . .
K.sub.N-1,2. That is, K.sub.a,2=K.sub.b,2 (.A-inverted.a and
.A-inverted.b where a, b,=0, 1, 2 . . . N-1, a.noteq.b).
[0756] Then, when a communication system that supports multiple
modulation methods selects one such supported method for use,
Condition #C19, Condition #C20, and Condition #C21 are preferably
met for the supported modulation method.
[0757] However, when multiple modulation methods are supported,
each such modulation method typically uses symbols transmitting a
different number of bits per symbols (though some may happen to use
the same number), Condition #C19, Condition #C20, and Condition
#C21 may not be satisfied for some modulation methods. In such a
case, the following conditions apply instead of Condition #C19,
Condition #C20, and Condition #C21.
(Condition #C22)
[0758] The difference between K.sub.a and K.sub.b satisfies 0 or 1.
That is, |K.sub.a|K.sub.b| satisfies 0 or 1 (.A-inverted.a,
.A-inverted.b, where a, b=0, 1, 2 . . . N-1 (a and b being integers
between 0 and N-1) a.noteq.b).
(Condition #C23)
[0759] The difference between K.sub.a,1 and .sub.Kb,1 satisfies 0
or 1. That is, |K.sub.a,1-K.sub.b,1| satisfies 0 or 1
(.A-inverted.a, .A-inverted.b, where a, b=0, 1, 2 . . . N-1 (a and
b being integers between 0 and N-1) a.noteq.b).
(Condition #C24)
[0759] [0760] The difference between K.sub.a,2 and K.sub.b,2
satisfies 0 or 1. That is, |K.sub.a,2-K.sub.b,2| satisfies 0 or 1
(.A-inverted.a, .A-inverted.b, where a, b=0, 1, 2 . . . N-1 (a and
b being integers between 0 and N-1) a.noteq.b).
[0761] As described above, bias among the phase changing values
being used to transmit the encoded blocks is removed by creating a
relationship between the encoded block and the phase changing
values. As such, data reception quality can be improved for the
reception device.
[0762] In the present Embodiment, N phase changing values (or phase
changing sets) are needed in order to perform a change of phase
having a period (cycle) of N with the method for a regular change
of phase. As such, N phase changing values (or phase changing sets)
P[0], P[1], P[2] . . . P[N-2], and P[N-1] are prepared. However,
methods exist for ordering the phases in the stated order with
respect to the frequency domain. No limitation is intended in this
regard. The N phase changing values (or phase changing sets) P[0],
P[1], P[2] . . . P[N-2], and P[N-1] may also change the phases of
blocks in the time domain or in the time-frequency domain to obtain
a symbol arrangement as described in Embodiment 1. Although the
above examples discuss a phase changing method with a period
(cycle) of N, the same effects are obtainable using N phase
changing values (or phase changing sets) at random. That is, the N
phase changing values (or phase changing sets) need not always have
regular periodicity. As long as the above-described conditions are
satisfied, great quality data reception improvements are realizable
for the reception device.
[0763] Furthermore, given the existence of modes for spatial
multiplexing MIMO methods, MIMO methods using a fixed precoding
matrix, space-time block coding methods, single-stream
transmission, and methods using a regular change of phase, the
transmission device (broadcaster, base station) may select any one
of these transmission methods.
[0764] As described in Non-Patent Literature 3, spatial
multiplexing MIMO methods involve transmitting signals s1 and s2,
which are mapped using a selected modulation method, on each of two
different antennas. MIMO methods using a fixed precoding matrix
involve performing precoding only (with no change in phase).
Further, space-time block coding methods are described in
Non-Patent Literature 9, 16, and 17. Single-stream transmission
methods involve transmitting signal s1, mapped with a selected
modulation method, from an antenna after performing predetermined
processing.
[0765] Schemes using multi-carrier transmission such as OFDM
involve a first carrier group made up of a plurality of carriers
and a second carrier group made up of a plurality of carriers
different from the first carrier group, and so on, such that
multi-carrier transmission is realized with a plurality of carrier
groups. For each carrier group, any of spatial multiplexing MIMO
schemes, MIMO schemes using a fixed precoding matrix, space-time
block coding schemes, single-stream transmission, and schemes using
a regular change of phase may be used. In particular, schemes using
a regular change of phase on a selected (sub-)carrier group are
preferably used to realize the present Embodiment.
[0766] When a change of phase by, for example, a phase changing
value for P[i] of X radians is performed on only one precoded
baseband signal, the phase changers of FIGS. 3, 4, 6, 12, 25, 29,
51, and 53 multiply precoded baseband signal z2' by e.sup.jX. Then,
when a change of phase by, for example, a phase changing set for
P[i] of X radians and Y radians is performed on both precoded
baseband signals, the phase changers from FIGS. 26, 27, 28, 52, and
54 multiply precoded baseband signal z2' by e.sup.jXand multiply
precoded baseband signal z1' by e.sup.jY.
Embodiment D 1
[0767] The present Embodiment is first described as a variation of
Embodiment 1. FIG. 67 illustrates a sample transmission device
pertaining to the present Embodiment. Components thereof operating
identically to those of FIG. 3 use the same reference numbers
thereas, and the description thereof is omitted for simplicity,
below. FIG. 67 differs from FIG. 3 in the insertion of a baseband
signal switcher 6702 directly following the weighting units.
Accordingly, the following explanations are primarily centred on
the baseband signal switcher 6702.
[0768] FIG. 21 illustrates the configuration of the weighting units
308A and 308B. The area of FIG. 21 enclosed in the dashed line
represents one of the weighting units. Baseband signal 307A is
multiplied by w11 to obtain w11s1(t), and multiplied by s21 to
obtain w21s1(t). Similarly, baseband signal 307B is multiplied by
s12 to obtain w12s2(t), and multiplied by w22 to obtain w22s2(t).
Next, z1(t)=w11s1(t)+w12s2(t) and z2(t)=w21s1(t)+w22s22(t) are
obtained. Here, as explained in Embodiment 1, s1(t) and s2(t) are
baseband signals modulated according to a modulation method such as
BPSK, QPSK, 8-PSK, 16-QAM, 32-QAM, 64-QAM, 256-QAM, 16-APSK and so
on. Both weighting units perform weighting using a fixed precoding
matrix. The precoding matrix uses, for example, the method of Math.
62 (formula 62), and satisfies the conditions of Math. 63 (formula
63) or Math. 64 (formula 64), all found below. However, this is
only an example. The value of a is not limited to Math. 63 (formula
63) and Math. 64 (formula 64), and may, for example, be 1, or may
be 0 (.alpha. is preferably a real number greater than or equal to
0, but may be also be an imaginary number).
[0769] Here, the precoding matrix is
[ Math . .times. 62 ] ##EQU00040## ( w .times. .times. 11 w .times.
.times. 12 w .times. .times. 21 w .times. .times. 22 ) = 1 .alpha.
2 + 1 .times. ( e j .times. .times. 0 .alpha. .times. e j .times.
.times. 0 .alpha. .times. e j .times. .times. 0 e j .times. .times.
.pi. ) ( formula .times. .times. 62 ) ##EQU00040.2##
[0770] In Math. 62 (formula 62), above, a is given by:
[ Math . .times. 63 ] ##EQU00041## .alpha. = 2 + 4 2 + 2 ( formula
.times. .times. 63 ) ##EQU00041.2##
[0771] Alternatively, in Math. 62 (formula 62), above, a may be
given by:
[ Math . .times. 64 ] ##EQU00042## .alpha. = 2 + 3 + 5 2 + 3 - 5 (
formula .times. .times. 64 ) ##EQU00042.2##
[0772] Alternatively, the precoding matrix is not restricted to
that of Math. 62 (formula 62), but may also be:
[ Math . .times. 65 ] ##EQU00043## ( w .times. .times. 11 w .times.
.times. 12 w .times. .times. 21 w .times. .times. 22 ) = ( a b c d
) ( formula .times. .times. 65 ) ##EQU00043.2##
[0773] where a=Ae.sup.j.delta.11, b=Be.sup.j.delta.12,
c=Ce.sup.j.delta.21, and d=De.sup.j.delta.22. Further, one of a, b,
c, and d may be equal to zero. For example: (1) a may be zero while
b, c, and d are non-zero, (2) b may be zero while a, c, and d are
non-zero, (3) c may be zero while a, b, and d are non-zero, or (4)
d may be zero while a, b, and c are non-zero.
[0774] Alternatively, any two of a, b, c, and d may be equal to
zero. For example, (1) a and d may be zero while b and c are
non-zero, or (2) b and c may be zero while a and d are
non-zero.
[0775] When any of the modulation method, error-correcting codes,
and the encoding rate thereof are changed, the precoding matrix in
use may also be set and changed, or the same precoding matrix may
be used as-is.
[0776] Next, the baseband signal switcher 6702 from FIG. 67 is
described. The baseband signal switcher 6702 takes weighted signal
309A and weighted signal 316B as input, performs baseband signal
switching, and outputs switched baseband signal 6701A and switched
baseband signal 6701B. The details of baseband signal switching are
as described with reference to FIG. 55. The baseband signal
switching performed in the present Embodiment differs from that of
FIG. 55 in terms of the signal used for switching. The following
describes the baseband signal switching of the present Embodiment
with reference to FIG. 68.
[0777] In FIG. 68, weighted signal 309A(p1(i)) has an in-phase
component I of I.sub.p1(i) and a quadrature component Q of
Q.sub.p1(i), while weighted signal 316B(p2(i)) has an in-phase
component I of I.sub.p2(i) and a quadrature component Q of
Q.sub.p2(i). In contrast, switched baseband signal 6701A(q1(i)) has
an in-phase component I of I.sub.q1(i) and a quadrature component Q
of Q.sub.q1(i), while switched baseband signal 6701B(q2(i) has an
in-phase component I of I.sub.q2(i) and a quadrature component Q of
Q.sub.q2(i). (Here, i represents (time or (carrier) frequency
order. In the example of FIG. 67, i represents time, though i may
also represent (carrier) frequency when FIG. 67 is applied to an
OFDM scheme, as in FIG. 12. These points are elaborated upon
below.)
[0778] Here, the baseband components are switched by the baseband
signal switcher 6702, such that: [0779] For switched baseband
signal q1(i), the in-phase component I may be I.sub.p1(i) while the
quadrature component Q may be Q.sub.p2(i), and for switched
baseband signal q2(i), the in-phase component I may be I.sub.p2(i)
while the quadrature component q may be Q.sub.p1(i). The modulated
signal corresponding to switched baseband signal q1(i) is
transmitted by transmit antenna 1 and the modulated signal
corresponding to switched baseband signal q2(i) is transmitted from
transmit antenna 2, simultaneously on a common frequency. As such,
the modulated signal corresponding to switched baseband signal
q1(i) and the modulated signal corresponding to switched baseband
signal q2(i) are transmitted from different antennas,
simultaneously on a common frequency. Alternatively, [0780] For
switched baseband signal q1(i), the in-phase component may be
I.sub.p1(i) while the quadrature component may be I.sub.p2(i), and
for switched baseband signal q2(i), the in-phase component may be
Q.sub.p1(i) while the quadrature component may be Q.sub.p2(i).
[0781] For switched baseband signal q1(i), the in-phase component
may be I.sub.p2(i) while the quadrature component may be
I.sub.p1(i), and for switched baseband signal q2(i), the in-phase
component may be Q.sub.p1(i) while the quadrature component may be
Q.sub.p2(i). [0782] For switched baseband signal q1(i), the
in-phase component may be I.sub.p1(i) while the quadrature
component may be I.sub.p2(i), and for switched baseband signal
q2(i), the in-phase component may be Q.sub.p2(i) while the
quadrature component may be Q.sub.p1(i). [0783] For switched
baseband signal q1(i), the in-phase component may be I.sub.p2(i)
while the quadrature component may be I.sub.p1(i), and for switched
baseband signal q2(i), the in-phase component may be Q.sub.p2(i)
while the quadrature component may be Q.sub.p1(i). [0784] For
switched baseband signal q1(i), the in-phase component may be
I.sub.p1(i) while the quadrature component may be Q.sub.p2(i), and
for switched baseband signal q2(i), the in-phase component may be
Q.sub.p1(i) while the quadrature component may be I.sub.p2(i).
[0785] For switched baseband signal q1(i), the in-phase component
may be Q.sub.p2(i) while the quadrature component may be
I.sub.p1(i), and for switched baseband signal q2(i), the in-phase
component may be I.sub.p2(i) while the quadrature component may be
Q.sub.p1(i). [0786] For switched baseband signal q1(i), the
in-phase component may be Q.sub.p2(i) while the quadrature
component may be I.sub.p1(i), and for switched baseband signal
q2(i), the in-phase component may be Q.sub.p1(i) while the
quadrature component may be I.sub.p2(i). [0787] For switched
baseband signal q2(i), the in-phase component may be I.sub.p1(i)
while the quadrature component may be I.sub.p2(i), and for switched
baseband signal q1(i), the in-phase component may be Q.sub.p1(i)
while the quadrature component may be Q.sub.p2(i). [0788] For
switched baseband signal q2(i), the in-phase component may be
I.sub.p2(i) while the quadrature component may be I.sub.p1(i), and
for switched baseband signal q1(i), the in-phase component may be
Q.sub.p1(i) while the quadrature component may be Q.sub.p2(i).
[0789] For switched baseband signal q2(i), the in-phase component
may be I.sub.p1(i) while the quadrature component may be
I.sub.p2(i), and for switched baseband signal q1(i), the in-phase
component may be Q.sub.p2(i) while the quadrature component may be
Q.sub.p1(i). [0790] For switched baseband signal q2(i), the
in-phase component may be I.sub.p2(i) while the quadrature
component may be I.sub.p1(i), and for switched baseband signal
q1(i), the in-phase component may be Q.sub.p2(i) while the
quadrature component may be Q.sub.p1(i). [0791] For switched
baseband signal q2(i), the in-phase component may be I.sub.p1(i)
while the quadrature component may be Q.sub.p2(i), and for switched
baseband signal q1(i), the in-phase component may be I.sub.p2(i)
while the quadrature component may be Q.sub.p1(i). [0792] For
switched baseband signal q2(i), the in-phase component may be
I.sub.p1(i) while the quadrature component may be Q.sub.p2(i), and
for switched baseband signal q1(i), the in-phase component may be
Q.sub.p1(i) while the quadrature component may be I.sub.p2(i).
[0793] For switched baseband signal q2(i), the in-phase component
may be Q.sub.p2(i) while the quadrature component may be
I.sub.p1(i), and for switched baseband signal q1(i), the in-phase
component may be I.sub.p2(i) while the quadrature component may be
Q.sub.p1(i). [0794] For switched baseband signal q2(i), the
in-phase component may be Q.sub.p2(i) while the quadrature
component may be I.sub.p1(i), and for switched baseband signal
q1(i), the in-phase component may be Q.sub.p1(i) while the
quadrature component may be I.sub.p2(i). Alternatively, the
weighted signals 309A and 316B are not limited to the
above-described switching of in-phase component and quadrature
component. Switching may be performed on in-phase components and
quadrature components greater than those of the two signals.
[0795] Also, while the above examples describe switching performed
on baseband signals having a common timestamp (common
(sub-)carrier) frequency), the baseband signals being switched need
not necessarily have a common timestamp (common (sub-)carrier)
frequency). For example, any of the following are possible. [0796]
For switched baseband signal q1(i), the in-phase component may be
I.sub.p1(i+v) while the quadrature component may be Q.sub.p2(i+w),
and for switched baseband signal q2(i), the in-phase component may
be I.sub.p2(i+w) while the quadrature component may be
Q.sub.p1(i+v). [0797] For switched baseband signal q1(i), the
in-phase component may be I.sub.p1(i+v) while the quadrature
component may be I.sub.p2(i+w), and for switched baseband signal
q2(i), the in-phase component may be Q.sub.p1(i+v) while the
quadrature component may be Q.sub.p2(i+w). [0798] For switched
baseband signal q1(i), the in-phase component may be I.sub.p2(i+w)
while the quadrature component may be I.sub.p1(i+v), and for
switched baseband signal q2(i), the in-phase component may be
Q.sub.p1(i+v) while the quadrature component may be Q.sub.p2(i+w).
[0799] For switched baseband signal q1(i), the in-phase component
may be I.sub.p1(i+v) while the quadrature component may be
I.sub.p2(i+w), and for switched baseband signal q2(i), the in-phase
component may be Q.sub.p2(i+w) while the quadrature component may
be Q.sub.p1(i+v). [0800] For switched baseband signal q1(i), the
in-phase component may be I.sub.p2(i+w) while the quadrature
component may be I.sub.p1(i+v), and for switched baseband signal
q2(i), the in-phase component may be Q.sub.p2(i+w) while the
quadrature component may be Q.sub.p1(i+v). [0801] For switched
baseband signal q1(i), the in-phase component may be I.sub.p1(i+v)
while the quadrature component may be Q.sub.p2(i+w), and for
switched baseband signal q2(i), the in-phase component may be
Q.sub.p1(i+v) while the quadrature component may be I.sub.p2(i+w).
[0802] For switched baseband signal q1(i), the in-phase component
may be Q.sub.p2(i+w) while the quadrature component may be
I.sub.p1(i+v), and for switched baseband signal q2(i), the in-phase
component may be I.sub.p2(i+w) while the quadrature component may
be Q.sub.p1(i+v). [0803] For switched baseband signal q1(i), the
in-phase component may be Q.sub.p2(i+w) while the quadrature
component may be I.sub.p1(i+v), and for switched baseband signal
q2(i), the in-phase component may be Q.sub.p1(i+v) while the
quadrature component may be I.sub.p2(i+w). [0804] For switched
baseband signal q2(i), the in-phase component may be I.sub.p1(i+v)
while the quadrature component may be I.sub.p2(i+w), and for
switched baseband signal q1(i), the in-phase component may be
Q.sub.p1(i+v) while the quadrature component may be Q.sub.p2(i+w).
[0805] For switched baseband signal q2(i), the in-phase component
may be I.sub.p2(i+w) while the quadrature component may be
I.sub.p1(i+v), and for switched baseband signal q1(i), the in-phase
component may be Q.sub.p1(i+v) while the quadrature component may
be Q.sub.p2(i+w). [0806] For switched baseband signal q2(i), the
in-phase component may be I.sub.p1(i+v) while the quadrature
component may be I.sub.p2(i+w), and for switched baseband signal
q1(i), the in-phase component may be Q.sub.p2(i+w) while the
quadrature component may be Q.sub.p1(i+v). [0807] For switched
baseband signal q2(i), the in-phase component may be I.sub.p2(i+w)
while the quadrature component may be I.sub.p1(i+v), and for
switched baseband signal q1(i), the in-phase component may be
Q.sub.p2(i+w) while the quadrature component may be Q.sub.p1(i+v).
[0808] For switched baseband signal q2(i), the in-phase component
may be I.sub.p1(i+v) while the quadrature component may be
Q.sub.p2(i+w), and for switched baseband signal q1(i), the in-phase
component may be I.sub.p2(i+w) while the quadrature component may
be Q.sub.p1(i+v). [0809] For switched baseband signal q2(i), the
in-phase component may be I.sub.p1(i+v) while the quadrature
component may be Q.sub.p2(i+w), and for switched baseband signal
q1(i), the in-phase component may be Q.sub.p1(i+v) while the
quadrature component may be I.sub.p2(i+w). [0810] For switched
baseband signal q2(i), the in-phase component may be Q.sub.p2(i+w)
while the quadrature component may be I.sub.p1(i+v), and for
switched baseband signal q1(i), the in-phase component may be
I.sub.p2(i+w) while the quadrature component may be Q.sub.p1(i+v).
[0811] For switched baseband signal q2(i), the in-phase component
may be Q.sub.p2(i+w) while the quadrature component may be
I.sub.p1(i+v), and for switched baseband signal q1(i), the in-phase
component may be Q.sub.p1(i+v) while the quadrature component may
be I.sub.p2(i+w).
[0812] Here, weighted signal 309A(p1(i)) has an in-phase component
I of I.sub.p1(i) and a quadrature component Q of Q.sub.p1(i), while
weighted signal 316B(p2(i)) has an in-phase component I of
I.sub.p2(i) and a quadrature component Q of Q.sub.p2(i). In
contrast, switched baseband signal 6701A(q1(i)) has an in-phase
component I of I.sub.q1(i) and a quadrature component Q of
Q.sub.q1(i), while switched baseband signal 6701B(q2(i)) has an
in-phase component I.sub.q2(i) and a quadrature component Q of
Q.sub.q2(i).
[0813] In FIG. 68, as described above, weighted signal 309A(p1(i))
has an in-phase component I of I.sub.p1(i) and a quadrature
component Q of Q.sub.p1(i), while weighted signal 316B(p2(i)) has
an in-phase component I of I.sub.p2(i) and a quadrature component Q
of Q.sub.p2(i). In contrast, switched baseband signal 6701A(q1(i))
has an in-phase component I of I.sub.q1(i) and a quadrature
component Q of Q.sub.q1(i), while switched baseband signal
6701B(q2(i)) has an in-phase component I.sub.q2(i) and a quadrature
component Q of Q.sub.q2(i).
[0814] As such, in-phase component I of I.sub.q1(i) and quadrature
component Q of Q.sub.q1(i) of switched baseband signal 6701A(q1(i))
and in-phase component I.sub.q2(i) and quadrature component Q of
Q.sub.q2(i) of baseband signal 6701B(q2(i)) are expressible as any
of the above.
[0815] As such, the modulated signal corresponding to switched
baseband signal 6701A(q1(i)) is transmitted from transmit antenna
312A, while the modulated signal corresponding to switched baseband
signal 6701B(q2(i)) is transmitted from transmit antenna 312B, both
being transmitted simultaneously on a common frequency. Thus, the
modulated signals corresponding to switched baseband signal
6701A(q1(i)) and switched baseband signal 6701B(q2(i)) are
transmitted from different antennas, simultaneously on a common
frequency.
[0816] Phase changer 317B takes switched baseband signal 6701B and
signal processing method information 315 as input and regularly
changes the phase of switched baseband signal 6701B for output.
This regular change is a change of phase performed according to a
predetermined phase changing pattern having a predetermined period
(cycle) (e.g., every n symbols (n being an integer, n.gtoreq.1) or
at a predetermined interval). The phase changing pattern is
described in detail in Embodiment 4.
[0817] Wireless unit 310B takes post-phase change signal 309B as
input and performs processing such as quadrature modulation, band
limitation, frequency conversion, amplification, and so on, then
outputs transmit signal 311B. Transmit signal 311B is then output
as radio waves by an antenna 312B.
[0818] FIG. 67, much like FIG. 3, is described as having a
plurality of encoders. However, FIG. 67 may also have an encoder
and a distributor like FIG. 4. In such a case, the signals output
by the distributor are the respective input signals for the
interleaver, while subsequent processing remains as described above
for FIG. 67, despite the changes required thereby.
[0819] FIG. 5 illustrates an example of a frame configuration in
the time domain for a transmission device according to the present
Embodiment. Symbol 500_1 is a symbol for notifying the reception
device of the transmission method. For example, symbol 500_1
conveys information such as the error-correction method used for
transmitting data symbols, the encoding rate thereof, and the
modulation method used for transmitting data symbols.
[0820] Symbol 501_1 is for estimating channel fluctuations for
modulated signal z1(t) (where t is time) transmitted by the
transmission device. Symbol 502_1 is a data symbol transmitted by
modulated signal z1(t) as symbol number u (in the time domain).
Symbol 503_1 is a data symbol transmitted by modulated signal z1(t)
as symbol number u+1.
[0821] Symbol 501_2 is for estimating channel fluctuations for
modulated signal z2(t) (where t is time) transmitted by the
transmission device. Symbol 502_2 is a data symbol transmitted by
modulated signal z2(t) as symbol number u. Symbol 503_2 is a data
symbol transmitted by modulated signal z1(t) as symbol number
u+1.
[0822] Here, the symbols of z1(t) and of z2(t) having the same
timestamp (identical timing) are transmitted from the transmit
antenna using the same (shared/common) frequency .
[0823] The following describes the relationships between the
modulated signals z1(t) and z2(t) transmitted by the transmission
device and the received signals r1(t) and r2(t) received by the
reception device.
[0824] In FIG. 5, 504#1 and 504#2 indicate transmit antennas of the
transmission device, while 505#1 and 505#2 indicate receive
antennas of the reception device. The transmission device transmits
modulated signal z1(t) from transmit antenna 504#1 and transmits
modulated signal z2(t) from transmit antenna 504#2. Here, modulated
signals z1(t) and z2(t) are assumed to occupy the same
(shared/common) frequency (bandwidth). The channel fluctuations in
the transmit antennas of the transmission device and the antennas
of the reception device are h.sub.11(t), h.sub.12(t), h.sub.21(t),
and h.sub.22(t), respectively. Assuming that receive antenna 505#1
of the reception device receives received signal r1(t) and that
receive antenna 505#2 of the reception device receives received
signal r2(t), the following relationship holds.
[ Math . .times. 66 ] ##EQU00044## ( r .times. .times. 1 .times. (
t ) r .times. .times. 2 .times. ( t ) ) = ( h 11 .function. ( t ) h
12 .function. ( t ) h 21 .function. ( t ) h 22 .function. ( t ) )
.times. ( z .times. .times. 1 .times. ( t ) z .times. .times. 2
.times. ( t ) ) ( formula .times. .times. 66 ) ##EQU00044.2##
[0825] FIG. 69 pertains to the weighting method (precoding method),
the baseband switching method, and the phase changing method of the
present Embodiment. The weighting unit 600 is a combined version of
the weighting units 308A and 308B from FIG. 67. As shown, stream
s1(t) and stream s2(t) correspond to the baseband signals 307A and
307B of FIG. 3. That is, the streams s1(t) and s2(t) are baseband
signals made up of an in-phase component I and a quadrature
component Q conforming to mapping by a modulation method such as
QPSK, 16-QAM, and 64-QAM. As indicated by the frame configuration
of FIG. 69, stream s1(t) is represented as s1(u) at symbol number
u, as s1(u+1) at symbol number u+1, and so forth. Similarly, stream
s2(t) is represented as s2(u) at symbol number u, as s2(u+1) at
symbol number u+1, and so forth. The weighting unit 600 takes the
baseband signals 307A (s1(t)) and 307B (s2(t)) as well as the
signal processing method information 315 from FIG. 67 as input,
performs weighting in accordance with the signal processing method
information 315, and outputs the weighted signals 309A (.sub.p1(t))
and 316B(.sub.p2(t)) from FIG. 67.
[0826] Here, given vector W1=(w11,w12) from the first row of the
fixed precoding matrix F, p.sub.1(t) can be expressed as Math. 67
(formula 67), below.
[Math. 67]
p1(t)=W1s1(t) (formula 67)
[0827] Here, given vector W2=(w21,w22) from the first row of the
fixed precoding matrix F, p.sub.2(t) can be expressed as Math. 68
(formula 68), below.
[Math. 68]
p2(t)=W2s2(t) (formula 68)
[0828] Accordingly, precoding matrix F may be expressed as
follows.
[ Math . .times. 69 ] ##EQU00045## F = ( w .times. .times. 11 w
.times. .times. 12 w .times. .times. 21 w .times. .times. 22 ) (
formula .times. .times. 69 ) ##EQU00045.2##
[0829] After the baseband signals have been switched, switched
baseband signal 6701A(q.sub.1(i)) has an in-phase component I of
Iq.sub.1(i) and a quadrature component Q of Qp.sub.1(i), and
switched baseband signal 6701B(q.sub.2(i)) has an in-phase
component I of Iq.sub.2(i) and a quadrature component Q of
Qq.sub.2(i). The relationships between all of these are as stated
above. When the phase changer uses phase changing formula y(t), the
post-phase change baseband signal 309B(q'2(i)) is given by Math. 70
(formula 70), below.
[Math. 70]
q2'(t)=y(t)q2(t) (formula 70)
[0830] Here, y(t) is a phase changing formula obeying a
predetermined method. For example, given a period (cycle) of four
and timestamp u, the phase changing formula may be expressed as
Math. 71 (formula 71), below.
[Math. 71]
y(u)=e.sup.j0 (formula 71)
[0831] Similarly, the phase changing formula for timestamp u+1 may
be, for example, as given by Math. 72 (formula 72).
[Math. 72]
y(u+1)=e.sup.j.pi./2 (formula 72)
[0832] That is, the phase changing formula for timestamp u+k
generalizes to Math. 73 (formula 73).
[ Math . .times. 73 ] ##EQU00046## y .function. ( u + k ) = e j
.times. k .times. .times. .pi. 2 ( formula .times. .times. 73 )
##EQU00046.2##
[0833] Note that Math. 71 (formula 71) through Math. 73 (formula
73) are given only as an example of a regular change of phase.
[0834] The regular change of phase is not restricted to a period
(cycle) of four. Improved reception capabilities (the
error-correction capabilities, to be exact) may potentially be
promoted in the reception device by increasing the period (cycle)
number (this does not mean that a greater period (cycle) is better,
though avoiding small numbers such as two is likely ideal.).
[0835] Furthermore, although Math. 71 (formula 71) through Math. 73
(formula 73), above, represent a configuration in which a change of
phase is carried out through rotation by consecutive predetermined
phases (in the above formula, every .pi./2), the change of phase
need not be rotation by a constant amount but may also be random.
For example, in accordance with the predetermined period (cycle) of
y(t), the phase may be changed through sequential multiplication as
shown in Math. 74 (formula 74) and Math. 75 (formula 75). The key
point of the regular change of phase is that the phase of the
modulated signal is regularly changed. The phase changing degree
variance rate is preferably as even as possible, such as from -.pi.
radians to .pi. radians. However, given that this concerns a
distribution, random variance is also possible.
.times. [ Math . .times. 74 ] e j .times. .times. 0 .fwdarw. e j
.times. .pi. 5 .fwdarw. e j .times. 2 .times. .pi. 5 .fwdarw. e j
.times. 3 .times. .pi. 5 .fwdarw. e j .times. 4 .times. .pi. 5
.fwdarw. e j .times. .times. .pi. .fwdarw. e j .times. 6 .times.
.pi. 5 .fwdarw. e j .times. 7 .times. .pi. 5 .fwdarw. e j .times. 8
.times. .pi. 5 .fwdarw. e j .times. 9 .times. .pi. 5 ( formula
.times. .times. 74 ) .times. [ Math . .times. 75 ] e j .times. .pi.
2 .fwdarw. e j .times. .times. .pi. .fwdarw. e j .times. 3 .times.
.pi. 2 .fwdarw. e j .times. .times. 2 .times. .pi. .fwdarw. e j
.times. .pi. 4 .fwdarw. e j .times. 3 4 .times. .pi. .fwdarw. e j
.times. 5 .times. .pi. 4 .fwdarw. e j .times. 7 .times. .pi. 4 (
formula .times. .times. 75 ) ##EQU00047##
[0836] As such, the weighting unit 600 of FIG. 6 performs precoding
using fixed, predetermined precoding weights, the baseband signal
switcher performs baseband signal switching as described above, and
the phase changer changes the phase of the signal input thereto
while regularly varying the degree of change.
[0837] When a specialized precoding matrix is used in the LOS
environment, the reception quality is likely to improve
tremendously. However, depending on the direct wave conditions, the
phase and amplitude components of the direct wave may greatly
differ from the specialized precoding matrix, upon reception. The
LOS environment has certain rules. Thus, data reception quality is
tremendously improved through a regular change of transmit signal
phase that obeys those rules. The present invention offers a signal
processing method for improving the LOS environment.
[0838] FIG. 7 illustrates a sample configuration of a reception
device 700 pertaining to the present embodiment. Wireless unit
703_X receives, as input, received signal 702_X received by antenna
701_X, performs processing such as frequency conversion, quadrature
demodulation, and the like, and outputs baseband signal 704_X.
[0839] Channel fluctuation estimator 705_1 for modulated signal z1
transmitted by the transmission device takes baseband signal 704_X
as input, extracts reference symbol 501_1 for channel estimation
from FIG. 5, estimates the value of h.sub.11 from Math. 66 (formula
66), and outputs channel estimation signal 706_1.
[0840] Channel fluctuation estimator 705_2 for modulated signal z2
transmitted by the transmission device takes baseband signal 704_X
as input, extracts reference symbol 501_2 for channel estimation
from FIG. 5, estimates the value of h.sub.12 from Math. 66 (formula
66), and outputs channel estimation signal 706_2.
[0841] Wireless unit 703_Y receives, as input, received signal
702_Y received by antenna 701_X, performs processing such as
frequency conversion, quadrature demodulation, and the like, and
outputs baseband signal 704_Y.
[0842] Channel fluctuation estimator 707_1 for modulated signal z1
transmitted by the transmission device takes baseband signal 704_Y
as input, extracts reference symbol 501_1 for channel estimation
from FIG. 5, estimates the value of h.sub.21 from Math. 66 (formula
66), and outputs channel estimation signal 708_1.
[0843] Channel fluctuation estimator 707_2 for modulated signal z2
transmitted by the transmission device takes baseband signal 704_Y
as input, extracts reference symbol 501_2 for channel estimation
from FIG. 5, estimates the value of h.sub.22 from Math. 66 (formula
66), and outputs channel estimation signal 708_2.
[0844] A control information decoder 709 receives baseband signal
704_X and baseband signal 704_Y as input, detects symbol 500_1 that
indicates the transmission method from FIG. 5, and outputs a
transmission device transmission method information signal 710.
[0845] A signal processor 711 takes the baseband signals 704_X and
704_Y, the channel estimation signals 706_1, 706_2, 708_1, and
708_2, and the transmission method information signal 710 as input,
performs detection and decoding, and then outputs received data
712_1 and 712_2.
[0846] Next, the operations of the signal processor 711 from FIG. 7
are described in detail. FIG. 8 illustrates a sample configuration
of the signal processor 711 pertaining to the present embodiment.
As shown, the signal processor 711 is primarily made up of an inner
MIMO detector, a soft-in/soft-out decoder, and a coefficient
generator. Non-Patent Literature 2 and Non-Patent Literature 3
describe the method of iterative decoding with this structure. The
MIMO system described in Non-Patent Literature 2 and Non-Patent
Literature 3 is a spatial multiplexing MIMO system, while the
present Embodiment differs from Non-Patent Literature 2 and
Non-Patent Literature 3 in describing a MIMO system that regularly
changes the phase over time, while using the precoding matrix and
performing baseband signal switching. Taking the (channel) matrix
H(t) of Math. 66 (formula 66), then by letting the precoding weight
matrix from FIG. 69 be F (here, a fixed precoding matrix remaining
unchanged for a given received signal) and letting the phase
changing formula used by the phase changer from FIG. 69 be Y(t)
(here, Y(t) changes over time t), then given the baseband signal
switching, the receive vector R(t)=(r1(t),r2(t)).sup.T and the
stream vector S(t)=(s1(t),s2(t)).sup.T lead to the decoding method
of Non-Patent Literature 2 and Non-Patent Literature 3, thus
enabling MIMO detection.
[0847] Accordingly, the coefficient generator 819 from FIG. 8 takes
a transmission method information signal 818 (corresponding to 710
from FIG. 7) indicated by the transmission device (information for
specifying the fixed precoding matrix in use and the phase changing
pattern used when the phase is changed) and outputs a signal
processing method information signal 820.
[0848] The inner MIMO detector 803 takes the signal processing
method information signal 820 as input and performs iterative
detection and decoding using the signal. The operations are
described below.
[0849] The processing unit illustrated in FIG. 8 must use a
processing method, as is illustrated in FIG. 10, to perform
iterative decoding (iterative detection). First, detection of one
codeword (or one frame) of modulated signal (stream) s1 and of one
codeword (or one frame) of modulated signal (stream) s2 are
performed. As a result, the soft-in/soft-out decoder obtains the
log-likelihood ratio of each bit of the codeword (or frame) of
modulated signal (stream) s1 and of the codeword (or frame) of
modulated signal (stream) s2. Next, the log-likelihood ratio is
used to perform a second round of detection and decoding. These
operations (referred to as iterative decoding (iterative
detection)) are performed multiple times . The following
explanations centre on the creation method of the log-likelihood
ratio of a symbol at a specific time within one frame.
[0850] In FIG. 8, a memory 815 takes baseband signal 801X
(corresponding to baseband signal 704_X from FIG. 7), channel
estimation signal group 802X (corresponding to channel estimation
signals 706_1 and 706_2 from FIG. 7), baseband signal 801Y
(corresponding to baseband signal 704_Y from FIG. 7), and channel
estimation signal group 802Y (corresponding to channel estimation
signals 708_1 and 708_2 from FIG. 7) as input, performs iterative
decoding (iterative detection), and stores the resulting matrix as
a transformed channel signal group. The memory 815 then outputs the
above-described signals as needed, specifically as baseband signal
816X, transformed channel estimation signal group 817X, baseband
signal 816Y, and transformed channel estimation signal group
817Y.
[0851] Subsequent operations are described separately for initial
detection and for iterative decoding (iterative detection).
[0852] (Initial Detection)
[0853] The inner MIMO detector 803 takes baseband signal 801X,
channel estimation signal group 802X, baseband signal 801Y, and
channel estimation signal group 802Y as input. Here, the modulation
method for modulated signal (stream) s1 and modulated signal
(stream) s2 is described as 16-QAM.
[0854] The inner MIMO detector 803 first computes a candidate
signal point corresponding to baseband signal 801X from the channel
estimation signal groups 802X and 802Y. FIG. 11 represents such a
calculation. In FIG. 11, each black dot is a candidate signal point
in the IQ plane. Given that the modulation method is 16-QAM, 256
candidate signal points exist. (However, FIG. 11 is only a
representation and does not indicate all 256 candidate signal
points.) Letting the four bits transmitted in modulated signal s1
be b0, b1, b2, and b3 and the four bits transmitted in modulated
signal s2 be b4, b5, b6, and b7, candidate signal points
corresponding to (b0, b1, b2, b3, b4, b5, b6, b7) are found in FIG.
11. The Euclidean squared distance between each candidate signal
point and each received signal point 1101 (corresponding to
baseband signal 801X) is then computed. The Euclidean squared
distance between each point is divided by the noise variance
G.sup.2. Accordingly, Ex(b0, b1, b2, b3, b4, b5, b6, b7) is
calculated. That is, the Euclidean squared distance between a
candidate signal point corresponding to (b0, b1, b2, b3, b4, b5,
b6, b7) and a received signal point is divided by the noise
variance. Here, each of the baseband signals and the modulated
signals s1 and s2 is a complex signal.
[0855] Similarly, the inner MIMO detector 803 calculates candidate
signal points corresponding to baseband signal 801Y from channel
estimation signal group 802X and channel estimation signal group
802Y, computes the Euclidean squared distance between each of the
candidate signal points and the received signal points
(corresponding to baseband signal 801Y), and divides the Euclidean
squared distance by the noise variance .sigma.2. Accordingly,
E.sub.Y(b0, b1, b2, b3, b4, b5, b6, b7) is calculated. That is,
E.sub.Y is the Euclidean squared distance between a candidate
signal point corresponding to (b0, b1, b2, b3, b4, b5, b6, b7) and
a received signal point, divided by the noise variance.
[0856] Next, Ex(b0, b1, b2, b3, b4, b5, b6, b7)+E.sub.Y(b0, b1, b2,
b3, b4, b5, b6, b7)=E(b0, b1, b2, b3, b4, b5, b6, b7) is
computed.
[0857] The inner MIMO detector 803 outputs E(b0, b1, b2, b3, b4,
b5, b6, b7) as the signal 804.
[0858] Log-likelihood calculator 805A takes the signal 804 as
input, calculates the log-likelihood of bits b0, b1, b2, and b3,
and outputs a log-likelihood signal 806A. Note that this
log-likelihood calculation produces the log-likelihood of a bit
being 1 and the log-likelihood of a bit being 0. The calculation
method is as shown in Math. 28 (formula 28), Math. 29 (formula 29),
and Math. 30 (formula 30), and the details are given by Non-Patent
Literature 2 and 3.
[0859] Similarly, log-likelihood calculator 805B takes the signal
804 as input, calculates the log-likelihood of bits b4, b5, b6, and
b7, and outputs log-likelihood signal 806B.
[0860] A deinterleaver (807A) takes log-likelihood signal 806A as
input, performs deinterleaving corresponding to that of the
interleaver (the interleaver (304A) from FIG. 67), and outputs
deinterleaved log-likelihood signal 808A.
[0861] Similarly, a deinterleaver (807B) takes log-likelihood
signal 806B as input, performs deinterleaving corresponding to that
of the interleaver (the interleaver (6704B) from FIG. 67), and
outputs deinterleaved log-likelihood signal 808B.
[0862] Log-likelihood ratio calculator 809A takes deinterleaved
log-likelihood signal 808A as input, calculates the log-likelihood
ratio of the bits encoded by encoder 6702A from FIG. 67, and
outputs log-likelihood ratio signal 810A.
[0863] Similarly, log-likelihood ratio calculator 809B takes
deinterleaved log-likelihood signal 808B as input, calculates the
log-likelihood ratio of the bits encoded by encoder 302B from FIG.
67, and outputs log-likelihood ratio signal 810B.
[0864] Soft-in/soft-out decoder 811A takes log-likelihood ratio
signal 810A as input, performs decoding, and outputs a decoded
log-likelihood ratio 812A.
[0865] Similarly, soft-in/soft-out decoder 811B takes
log-likelihood ratio signal 810B as input, performs decoding, and
outputs decoded log-likelihood ratio 812B.
[0866] (Iterative Decoding (Iterative Detection), k Iterations)
[0867] The interleaver (813A) takes the k-1th decoded
log-likelihood ratio 812A decoded by the soft-in/soft-out decoder
as input, performs interleaving, and outputs interleaved
log-likelihood ratio 814A. Here, the interleaving pattern used by
the interleaver (813A) is identical to that of the interleaver
(304A) from FIG. 67.
[0868] Another interleaver (813B) takes the k-1th decoded
log-likelihood ratio 812B decoded by the soft-in/soft-out decoder
as input, performs interleaving, and outputs interleaved
log-likelihood ratio 814B. Here, the interleaving pattern used by
the interleaver (813B) is identical to that of the other
interleaver (304B) from FIG. 67.
[0869] The inner MIMO detector 803 takes baseband signal 816X,
transformed channel estimation signal group 817X, baseband signal
816Y, transformed channel estimation signal group 817Y, interleaved
log-likelihood ratio 814A, and interleaved log-likelihood ratio
814B as input. Here, baseband signal 816X, transformed channel
estimation signal group 817X, baseband signal 816Y, and transformed
channel estimation signal group 817Y are used instead of baseband
signal 801X, channel estimation signal group 802X, baseband signal
801Y, and channel estimation signal group 802Y because the latter
cause delays due to the iterative decoding.
[0870] The iterative decoding operations of the inner MIMO detector
803 differ from the initial detection operations thereof in that
the interleaved log-likelihood ratios 814A and 814B are used in
signal processing for the former. The inner MIMO detector 803 first
calculates E(b0, b1, b2, b3, b4, b5, b6, b7) in the same manner as
for initial detection. In addition, the coefficients corresponding
to Math. 11 (formula 11) and Math. 32 (formula 32) are computed
from the interleaved log-likelihood ratios 814A and 914B. The value
of E(b0, b1, b2, b3, b4, b5, b6, b7) is corrected using the
coefficients so calculated to obtain E'(b0, b1, b2, b3, b4, b5, b6,
b7), which is output as the signal 804.
[0871] The log-likelihood calculator 805A takes the signal 804 as
input, calculates the log-likelihood of bits b0, b1, b2, and b3,
and outputs the log-likelihood signal 806A. Note that this
log-likelihood calculation produces the log-likelihood of a bit
being 1 and the log-likelihood of a bit being 0. The calculation
method is as shown in Math. 31 (formula 31) through Math. 35
(formula 35), and the details are given by Non-Patent Literature 2
and 3.
[0872] Similarly, log-likelihood calculator 805B takes the signal
804 as input, calculates the log-likelihood of bits b4, b5, b6, and
b7, and outputs log-likelihood signal 806B. Operations performed by
the deinterleaver onwards are similar to those performed for
initial detection.
[0873] While FIG. 8 illustrates the configuration of the signal
processor when performing iterative detection, this structure is
not absolutely necessary as good reception improvements are
obtainable by iterative detection alone. As long as the components
needed for iterative detection are present, the configuration need
not include the interleavers 813A and 813B. In such a case, the
inner MIMO detector 803 does not perform iterative detection.
[0874] As shown in Non-Patent Literature 5 and the like, QR
decomposition may also be used to perform initial detection and
iterative detection. Also, as indicated by Non-Patent Literature
11, MMSE and ZF linear operations may be performed when performing
initial detection.
[0875] FIG. 9 illustrates the configuration of a signal processor
unlike that of FIG. 8, that serves as the signal processor for
modulated signals transmitted by the transmission device from FIG.
4 as used in FIG. 67. The point of difference from FIG. 8 is the
number of soft-in/soft-out decoders. A soft-in/soft-out decoder 901
takes the log-likelihood ratio signals 810A and 810B as input,
performs decoding, and outputs a decoded log-likelihood ratio 902.
A distributor 903 takes the decoded log-likelihood ratio 902 as
input for distribution. Otherwise, the operations are identical to
those explained for FIG. 8.
[0876] As described above, when a transmission device according to
the present Embodiment using a MIMO system transmits a plurality of
modulated signals from a plurality of antennas, changing the phase
over time while multiplying by the precoding matrix so as to
regularly change the phase results in improvements to data
reception quality for a reception device in a LOS environment,
where direct waves are dominant, compared to a conventional spatial
multiplexing MIMO system.
[0877] In the present Embodiment, and particularly in the
configuration of the reception device, the number of antennas is
limited and explanations are given accordingly. However, the
Embodiment may also be applied to a greater number of antennas. In
other words, the number of antennas in the reception device does
not affect the operations or advantageous effects of the present
Embodiment.
[0878] Further, in the present Embodiments, the encoding is not
particularly limited to LDPC codes. Similarly, the decoding method
is not limited to implementation by a soft-in/soft-out decoder
using sum-product decoding. The decoding method used by the
soft-in/soft-out decoder may also be, for example, the BCJR
algorithm, S OVA, and the Max-Log-Map algorithm. Details are
provided in Non-Patent Literature 6.
[0879] In addition, although the present Embodiment is described
using a single-carrier method, no limitation is intended in this
regard. The present Embodiment is also applicable to multi-carrier
transmission. Accordingly, the present Embodiment may also be
realized using, for example, spread-spectrum communications, OFDM,
SC-FDMA, SC-OFDM, wavelet OFDM as described in Non-Patent
Literature 7, and so on. Furthermore, in the present Embodiment,
symbols other than data symbols, such as pilot symbols (preamble,
unique word, and so on) or symbols transmitting control
information, may be arranged within the frame in any manner.
[0880] The following describes an example in which OFDM is used as
a multi-carrier method.
[0881] FIG. 70 illustrates the configuration of a transmission
device using OFDM. In FIG. 70, components operating in the manner
described for FIGS. 3, 12, and 67 use identical reference
numbers.
[0882] An OFDM-related processor 1201A takes weighted signal 309A
as input, performs OFDM-related processing thereon, and outputs
transmit signal 1202A. Similarly, OFDM-related processor 1201B
takes post-phase change signal 309B as input, performs OFDM-related
processing thereon, and outputs transmit signal 1202B
[0883] FIG. 13 illustrates a sample configuration of the
OFDM-related processors 1201A and 1201B and onward from FIG. 70.
Components 1301A through 1310A belong between 1201A and 312A from
FIG. 70, while components 1301B through 1310B belong between 1201B
and 312B.
[0884] Serial-to-parallel converter 1302A performs
serial-to-parallel conversion on switched baseband signal 1301A
(corresponding to switched baseband signal 6701A from FIG. 70) and
outputs parallel signal 1303A.
[0885] Reorderer 1304A takes parallel signal 1303A as input,
performs reordering thereof, and outputs reordered signal 1305A.
Reordering is described in detail later.
[0886] IFFT unit 1306A takes reordered signal 1305A as input,
applies an IFFT thereto, and outputs post-IFFT signal 1307A.
[0887] Wireless unit 1308A takes post-IFFT signal 1307A as input,
performs processing such as frequency conversion and amplification,
thereon, and outputs modulated signal 1309A. Modulated signal 1309A
is then output as radio waves by antenna 1310A.
[0888] Serial-to-parallel converter 1302B performs
serial-to-parallel conversion on post-phase change 1301B
(corresponding to post-phase change 309B from FIG. 12) and outputs
parallel signal 1303B.
[0889] Reorderer 1304B takes parallel signal 1303B as input,
performs reordering thereof, and outputs reordered signal 1305B.
Reordering is described in detail later.
[0890] IFFT unit 1306B takes reordered signal 1305B as input,
applies an IFFT thereto, and outputs post-IFFT signal 1307B.
[0891] Wireless unit 1308B takes post-IFFT signal 1307B as input,
performs processing such as frequency conversion and amplification
thereon, and outputs modulated signal 1309B. Modulated signal 1309B
is then output as radio waves by antenna 1310A.
[0892] The transmission device from FIG. 67 does not use a
multi-carrier transmission method. Thus, as shown in FIG. 69, a
change of phase is performed to achieve a period (cycle) of four
and the post-phase change symbols are arranged in the time domain.
As shown in FIG. 70, when multi-carrier transmission, such as OFDM,
is used, then, naturally, symbols in precoded baseband signals
having undergone switching and phase changing may be arranged in
the time domain as in FIG. 67, and this may be applied to each
(sub-)carrier. However, for multi-carrier transmission, the
arrangement may also be in the frequency domain, or in both the
frequency domain and the time domain. The following describes these
arrangements.
[0893] FIGS. 14A and 14B indicate frequency on the horizontal axes
and time on the vertical axes thereof, and illustrate an example of
a symbol reordering method used by the reorderers 1301A and 1301B
from FIG. 13. The frequency axes are made up of (sub-)carriers 0
through 9. The modulated signals z1 and z2 share common timestamps
(timing) and use a common frequency band. FIG. 14A illustrates a
reordering method for the symbols of modulated signal z1, while
FIG. 14B illustrates a reordering method for the symbols of
modulated signal z2. With respect to the symbols of switched
baseband signal 1301A input to serial-to-parallel converter 1302A,
the ordering is #0, #1, #2, #3, and so on. Here, given that the
example deals with a period (cycle) of four, #0, #1, #2, and #3 are
equivalent to one period (cycle). Similarly, #4n, #4n+1, #4n+2, and
#4n+3 (n being a non-zero positive integer) are also equivalent to
one period (cycle).
[0894] As shown in FIG. 14A, symbols #0, #1, #2, #3, and so on are
arranged in order, beginning at carrier 0. Symbols #0 through #9
are given timestamp $1, followed by symbols #10 through #19 which
are given timestamp #2, and so on in a regular arrangement. Here,
modulated signals z1 and z2 are complex signals.
[0895] Similarly, with respect to the symbols of weighted signal
1301B input to serial-to-parallel converter 1302B, the assigned
ordering is #0, #1, #2, #3, and so on. Here, given that the example
deals with a period (cycle) of four, a different change in phase is
applied to each of #0, #1, #2, and #3, which are equivalent to one
period (cycle). Similarly, a different change in phase is applied
to each of #4n, #4n+1, #4n+2, and #4n+3 (n being a non-zero
positive integer), which are also equivalent to one period
(cycle).
[0896] As shown in FIG. 14B, symbols #0, #1, #2, #3, and so on are
arranged in order, beginning at carrier 0. Symbols #0 through #9
are given timestamp $1, followed by symbols #10 through #19 which
are given timestamp $2, and so on in a regular arrangement.
[0897] The symbol group 1402 shown in FIG. 14B corresponds to one
period (cycle) of symbols when the phase changing method of FIG. 69
is used. Symbol #0 is the symbol obtained by using the phase at
timestamp u in FIG. 69, symbol #1 is the symbol obtained by using
the phase at timestamp u+1 in FIG. 69, symbol #2 is the symbol
obtained by using the phase at timestamp u+2 in FIG. 69, and symbol
#3 is the symbol obtained by using the phase at timestamp u+3 in
FIG. 69. Accordingly, for any symbol #x, symbol #x is the symbol
obtained by using the phase at timestamp u in FIG. 69 when x mod 4
equals 0 (i.e., when the remainder of x divided by 4 is 0, mod
being the modulo operator), symbol #x is the symbol obtained by
using the phase at timestamp x+1 in FIG. 69 when x mod 4 equals 1,
symbol #x is the symbol obtained by using the phase at timestamp
x+2 in FIG. 69 when x mod 4 equals 2, and symbol #x is the symbol
obtained by using the phase at timestamp x+3 in FIG. 69 when x mod
4 equals 3.
[0898] In the present Embodiment, modulated signal z1 shown in FIG.
14A has not undergone a change of phase.
[0899] As such, when using a multi-carrier transmission method such
as OFDM, and unlike single carrier transmission, symbols can be
arranged in the frequency domain. Of course, the symbol arrangement
method is not limited to those illustrated by FIGS. 14A and 14B.
Further examples are shown in FIGS. 15A, 15B, 16A, and 16B.
[0900] FIGS. 15A and 15B indicate frequency on the horizontal axes
and time on the vertical axes thereof, and illustrate an example of
a symbol reordering scheme used by the reorderers 1301A and 1301B
from FIG. 13 that differs from that of FIGS. 14A and 14B. FIG. 15A
illustrates a reordering scheme for the symbols of modulated signal
z1, while FIG. 15B illustrates a reordering scheme for the symbols
of modulated signal z2. FIGS. 15A and 15B differ from FIGS. 14A and
14B in that different reordering methods are applied to the symbols
of modulated signal z1 and to the symbols of modulated signal z2.
In FIG. 15B, symbols #0 through #5 are arranged at carriers 4
through 9, symbols #6 though #9 are arranged at carriers 0 through
3, and this arrangement is repeated for symbols #10 through #19.
Here, as in FIG. 14B, symbol group 1502 shown in FIG. 15B
corresponds to one period (cycle) of symbols when the phase
changing method of FIG. 6 is used.
[0901] FIGS. 16A and 16B indicate frequency on the horizontal axes
and time on the vertical axes thereof, and illustrate an example of
a symbol reordering method used by the reorderers 1301A and 1301B
from FIG. 13 that differs from that of FIGS. 14A and 14B. FIG. 16A
illustrates a reordering method for the symbols of modulated signal
z1, while FIG. 16B illustrates a reordering method for the symbols
of modulated signal z2. FIGS. 16A and 16B differ from FIGS. 14A and
14B in that, while FIGS. 14A and 14B showed symbols arranged at
sequential carriers, FIGS. 16A and 16B do not arrange the symbols
at sequential carriers. Obviously, for FIGS. 16A and 16B, different
reordering methods may be applied to the symbols of modulated
signal z1 and to the symbols of modulated signal z2 as in FIGS. 15A
and 15B.
[0902] FIGS. 17A and 17B indicate frequency on the horizontal axes
and time on the vertical axes thereof, and illustrate an example of
a symbol reordering method used by the reorderers 1301A and 1301B
from FIG. 13 that differs from those of FIGS. 14A through 16B. FIG.
17A illustrates a reordering method for the symbols of modulated
signal z1 and FIG. 17B illustrates a reordering method for the
symbols of modulated signal z2. While FIGS. 14A through 16B show
symbols arranged with respect to the frequency axis, FIGS. 17A and
17B use the frequency and time axes together in a single
arrangement.
[0903] While FIG. 69 describes an example where the change of phase
is performed in a four slot period (cycle), the following example
describes an eight slot period (cycle). In FIGS. 17A and 17B, the
symbol group 1702 is equivalent to one period (cycle) of symbols
when the phase changing scheme is used (i.e., to eight symbols)
such that symbol #0 is the symbol obtained by using the phase at
timestamp u, symbol #1 is the symbol obtained by using the phase at
timestamp u+1, symbol #2 is the symbol obtained by using the phase
at timestamp u+2, symbol #3 is the symbol obtained by using the
phase at timestamp u+3, symbol #4 is the symbol obtained by using
the phase at timestamp u+4, symbol #5 is the symbol obtained by
using the phase at timestamp u+5, symbol #6 is the symbol obtained
by using the phase at timestamp u+6, and symbol #7 is the symbol
obtained by using the phase at timestamp u+7. Accordingly, for any
symbol #x, symbol #x is the symbol obtained by using the phase at
timestamp u when x mod 8 equals 0, symbol #x is the symbol obtained
by using the phase at timestamp u+1 when x mod 8 equals 1, symbol
#x is the symbol obtained by using the phase at timestamp u+2 when
x mod 8 equals 2, symbol #x is the symbol obtained by using the
phase at timestamp u+3 when x mod 8 equals 3, symbol #x is the
symbol obtained by using the phase at timestamp u+4 when x mod 8
equals 4, symbol #x is the symbol obtained by using the phase at
timestamp u+5 when x mod 8 equals 5, symbol #x is the symbol
obtained by using the phase at timestamp u+6 when x mod 8 equals 6,
and symbol #x is the symbol obtained by using the phase at
timestamp u+7 when x mod 8 equals 7. In FIGS. 17A and 17B four
slots along the time axis and two slots along the frequency axis
are used for a total of 4.times.2=8 slots, in which one period
(cycle) of symbols is arranged. Here, given m.times.n symbols per
period (cycle) (i.e., m.times.n different phases are available for
multiplication), then n slots (carriers) in the frequency domain
and m slots in the time domain should be used to arrange the
symbols of each period (cycle), such that m>n. This is because
the phase of direct waves fluctuates slowly in the time domain
relative to the frequency domain. Accordingly, the present
Embodiment performs a regular change of phase that reduces the
effect of steady direct waves. Thus, the phase changing period
(cycle) should preferably reduce direct wave fluctuations.
Accordingly, m should be greater than n. Taking the above into
consideration, using the time and frequency domains together for
reordering, as shown in FIGS. 17A and 17B, is preferable to using
either of the frequency domain or the time domain alone due to the
strong probability of the direct waves becoming regular. As a
result, the effects of the present invention are more easily
obtained. However, reordering in the frequency domain may lead to
diversity gain due the fact that frequency-domain fluctuations are
abrupt. As such, using the frequency and time domains together for
reordering is not always ideal.
[0904] FIGS. 18A and 18B indicate frequency on the horizontal axes
and time on the vertical axes thereof, and illustrate an example of
a symbol reordering method used by the reorderers 1301A and 1301B
from FIG. 13 that differs from that of FIGS. 17A and 17B. FIG. 18A
illustrates a reordering method for the symbols of modulated signal
z1, while FIG. 18B illustrates a reordering method for the symbols
of modulated signal z2. Much like FIGS. 17A and 17B, FIGS. 18A and
18B illustrate the use of the time and frequency domains, together.
However, in contrast to FIGS. 17A and 17B, where the frequency
domain is prioritized and the time domain is used for secondary
symbol arrangement, FIGS. 18A and 18B prioritize the time domain
and use the frequency domain for secondary symbol arrangement. In
FIG. 18B, symbol group 1802 corresponds to one period (cycle) of
symbols when the phase changing method is used.
[0905] In FIGS. 17A, 17B, 18A, and 18B, the reordering method
applied to the symbols of modulated signal z1 and the symbols of
modulated signal z2 may be identical or may differ as like in FIGS.
15A and 15B. Either approach allows good reception quality to be
obtained. Also, in FIGS. 17A, 17B, 18A, and 18B, the symbols may be
arranged non-sequentially as in FIGS. 16A and 16B. Either approach
allows good reception quality to be obtained.
[0906] FIG. 22 indicates frequency on the horizontal axis and time
on the vertical axis thereof, and illustrates an example of a
symbol reordering method used by the reorderers 1301A and 1301B
from FIG. 13 that differs from the above. FIG. 22 illustrates a
regular phase changing method using four slots, similar to
timestamps u through u+3 from FIG. 69. The characteristic feature
of FIG. 22 is that, although the symbols are reordered with respect
to the frequency domain, when read along the time axis, a periodic
shift of n (n=1 in the example of FIG. 22) symbols is apparent. The
frequency-domain symbol group 2210 in FIG. 22 indicates four
symbols to which are applied the changes of phase at timestamps u
through u+3 from FIG. 69.
[0907] Here, symbol #0 is obtained through a change of phase at
timestamp u, symbol #1 is obtained through a change of phase at
timestamp u+1, symbol #2 is obtained through a change of phase at
timestamp u+2, and symbol #3 is obtained through a change of phase
at timestamp u+3.
[0908] Similarly, for frequency-domain symbol group 2220, symbol #4
is obtained through a change of phase at timestamp u, symbol #5 is
obtained through a change of phase at timestamp u+1, symbol #6 is
obtained through a change of phase at timestamp u+2, and symbol #7
is obtained through a change of phase at timestamp u+3.
[0909] The above-described change of phase is applied to the symbol
at timestamp $1. However, in order to apply periodic shifting with
respect to the time domain, the following change of phases are
applied to symbol groups 2201, 2202, 2203, and 2204.
[0910] For time-domain symbol group 2201, symbol #0 is obtained
through a change of phase at timestamp u, symbol #9 is obtained
through a change of phase at timestamp u+1, symbol #18 is obtained
through a change of phase at timestamp u+2, and symbol #27 is
obtained through a change of phase at timestamp u+3.
[0911] For time-domain symbol group 2202, symbol #28 is obtained
through a change of phase at timestamp u, symbol #1 is obtained
through a change of phase at timestamp u+1, symbol #10 is obtained
through a change of phase at timestamp u+2, and symbol #19 is
obtained through a change of phase at timestamp u+3.
[0912] For time-domain symbol group 2203, symbol #20 is obtained
through a change of phase at timestamp u, symbol #29 is obtained
through a change of phase at timestamp u+1, symbol #2 is obtained
through a change of phase at timestamp u+2, and symbol #11 is
obtained through a change of phase at timestamp u+3.
[0913] For time-domain symbol group 2204, symbol #12 is obtained
through a change of phase at timestamp u, symbol #21 is obtained
through a change of phase at timestamp u+1, symbol #30 is obtained
through a change of phase at timestamp u+2, and symbol #3 is
obtained through a change of phase at timestamp u+3.
[0914] The characteristic feature of FIG. 22 is seen in that,
taking symbol #11 as an example, the two neighbouring symbols
thereof having the same timestamp in the frequency domain (#10 and
#12) are both symbols changed using a different phase than symbol
#11, and the two neighbouring symbols thereof having the same
carrier in the time domain (#2 and #20) are both symbols changed
using a different phase than symbol #11. This holds not only for
symbol #11, but also for any symbol having two neighbouring symbols
in the frequency domain and the time domain. Accordingly, the
change of phase is effectively carried out. This is highly likely
to improve data reception quality as influence from regularizing
direct waves is less prone to reception.
[0915] Although FIG. 22 illustrates an example in which n=1, the
invention is not limited in this manner. The same may be applied to
a case in which n=3. Furthermore, although FIG. 22 illustrates the
realization of the above-described effects by arranging the symbols
in the frequency domain and advancing in the time domain so as to
achieve the characteristic effect of imparting a periodic shift to
the symbol arrangement order, the symbols may also be randomly (or
regularly) arranged to the same effect.
[0916] Although the present Embodiment describes a variation of
Embodiment 1 in which a baseband signal switcher is inserted before
the change of phase, the present Embodiment may also be realized as
a combination with Embodiment 2, such that the baseband signal
switcher is inserted before the change of phase in FIGS. 26 and 28.
Accordingly, in FIG. 26, phase changer 317A takes switched baseband
signal 6701A(q.sub.1(i)) as input, and phase changer 317B takes
switched baseband signal 6701B(q.sub.2(i)) as input. The same
applies to the phase changers 317A and 317B from FIG. 28.
[0917] The following describes a method of allowing the reception
device to obtain good received signal quality for data, regardless
of the reception device arrangement, by considering the location of
the reception device with respect to the transmission device.
[0918] FIG. 31 illustrates an example of frame configuration for a
portion of the symbols within a signal in the time-frequency
domains, given a transmission method where a regular change of
phase is performed for a multi-carrier method such as OFDM.
[0919] FIG. 31 illustrates the frame configuration of modulated
signal z2' corresponding to the switched baseband signal input to
phase changer 317B from FIG. 67. Each square represents one symbol
(although both signals s1 and s2 are included for precoding
purposes, depending on the precoding matrix, only one of signals s1
and s2 may be used).
[0920] Consider symbol 3100 at carrier 2 and timestamp $2 of FIG.
31. The carrier here described may alternatively be termed a
sub-carrier.
[0921] Within carrier 2, there is a very strong correlation between
the channel conditions for symbol 3100A at carrier 2, timestamp $2
and the channel conditions for the time domain nearest-neighbour
symbols to timestamp $2, i.e., symbol 3013 at timestamp $1 and
symbol 3101 at timestamp $3 within carrier 2.
[0922] Similarly, for timestamp $2, there is a very strong
correlation between the channel conditions for symbol 3100 at
carrier 2, timestamp $2 and the channel conditions for the
frequency-domain nearest-neighbour symbols to carrier 2, i.e.,
symbol 3104 at carrier 1, timestamp $2 and symbol 3104 at timestamp
$2, carrier 3.
[0923] As described above, there is a very strong correlation
between the channel conditions for symbol 3100 and the channel
conditions for each symbol 3101, 3102, 3103, and 3104.
[0924] The present description considers N different phases (N
being an integer, N.gtoreq.2) for multiplication in a transmission
method where the phase is regularly changed. The symbols
illustrated in FIG. 31 are indicated as e.sup.j0, for example. This
signifies that this symbol is signal z2' from FIG. 6 having
undergone a change in phase through multiplication by e.sup.j0.
That is, the values given for the symbols in FIG. 31 are the value
of y(t) as given by Math. 70 (formula 70).
[0925] The present Embodiment takes advantage of the high
correlation in channel conditions existing between neighbouring
symbols in the frequency domain and/or neighbouring symbols in the
time domain in a symbol arrangement enabling high data reception
quality to be obtained by the reception device receiving the
post-phase change symbols.
[0926] In order to achieve this high data reception quality,
conditions #D1-1 and #D1-2 must be met.
(Condition #D1-1)
[0927] As shown in FIG. 69, for a transmission method involving a
regular change of phase performed on switched baseband signal q2
using a multi-carrier method such as OFDM, time X, carrier Y must
be a symbol for transmitting data (hereinafter, data symbol),
neighbouring symbols in the time domain, i.e., at time X-1, carrier
Y and at time X+1, carrier Y must also be data symbols, and a
different change of phase must be performed on switched baseband
signal q2 corresponding to each of these three data symbols, i.e.,
on switched baseband signal q2 at time X, carrier Y, at time X-1,
carrier Y and at time X+1, carrier Y.
(Condition #D1-2)
[0928] As shown in FIG. 69, for a transmission method involving a
regular change of phase performed on switched baseband signal q2
using a multi-carrier method such as OFDM, time X, carrier Y must
be a symbol for transmitting data (hereinafter, data symbol),
neighbouring symbols in the time domain, i.e., at time X, carrier
Y+1 and at time X, carrier Y-1 must also be data symbols, and a
different change of phase must be performed on switched baseband
signal q2 corresponding to each of these three data symbols, i.e.,
on switched baseband signal q2 at time X, carrier Y, at time X,
carrier Y-1 and at time X, carrier Y+1.
[0929] Ideally, a data symbol should satisfy Condition #D1-1.
Similarly, the data symbols should satisfy Condition #D1-2.
[0930] The reasons supporting Conditions #D1-1 and #D1-2 are as
follows.
[0931] A very strong correlation exists between the channel
conditions of given symbol of a transmit signal (hereinafter,
symbol A) and the channel conditions of the symbols neighbouring
symbol A in the time domain, as described above.
[0932] Accordingly, when three neighbouring symbols in the time
domain each have different phases, then despite reception quality
degradation in the LOS environment (poor signal quality caused by
degradation in conditions due to phase relations despite high
signal quality in terms of SNR) for symbol A, the two remaining
symbols neighbouring symbol A are highly likely to provide good
reception quality. As a result, good received signal quality is
achievable after error correction and decoding.
[0933] Similarly, a very strong correlation exists between the
channel conditions of given symbol of a transmit signal (symbol A)
and the channel conditions of the symbols neighbouring symbol A in
the frequency domain, as described above.
[0934] Accordingly, when three neighbouring symbols in the
frequency domain each have different phases, then despite reception
quality degradation in the LOS environment (poor signal quality
caused by degradation in conditions due to direct wave phase
relationships despite high signal quality in terms of SNR) for
symbol A, the two remaining symbols neighbouring symbol A are
highly likely to provide good reception quality. As a result, good
received signal quality is achievable after error correction and
decoding.
[0935] By combining Conditions #D1-1 and #D1-2, ever greater data
reception quality is likely achievable for the reception device.
Accordingly, the following Condition #D1-3 can be derived.
(Condition #D1-3)
[0936] As shown in FIG. 69, for a transmission method involving a
regular change of phase performed on switched baseband signal q2
using a multi-carrier method such as OFDM, time X, carrier Y must
be a symbol for transmitting data (data symbol), neighbouring
symbols in the time domain, i.e., at time X-1, carrier Y and at
time X+1, carrier Y must also be data symbols, and neighbouring
symbols in the frequency domain, i.e., at time X, carrier Y-1 and
at time X, carrier Y+1 must also be data symbols, such that a
different change of phase must be performed on switched baseband
signal q2 corresponding to each of these five data symbols, i.e.,
on switched baseband signal q2 at time X, carrier Y, at time X,
carrier Y-1, at time X, carrier Y+1, at time X-1, carrier Y and at
time X+1, carrier Y.
[0937] Here, the different changes in phase are as follows. Phase
changes are defined from 0 radians to 2.pi. radians. For example,
for time X, carrier Y, a phase change of e.sup.j.theta.X,Y is
applied to precoded baseband signal q.sub.2 from FIG. 69, for time
X-1, carrier Y, a phase change of e.sup.j.theta.X-1,Y is applied to
precoded baseband signal q2 from FIG. 69, for time X+1, carrier Y,
a phase change of e.sup.j.theta.X+1,Y is applied to precoded
baseband signal q2 from FIG. 69, such that
0.ltoreq..theta..sub.X,Y<2.pi.,
0.ltoreq..theta..sub.X-1,Y>2.pi., and
0.ltoreq..theta..sub.X+1,Y<2.pi., .quadrature..quadrature.all
units being in radians. Accordingly, for Condition #D1-1, it
follows that .theta..sub.X,Y.noteq..theta..sub.X,Y-1,
.theta..sub.X,Y.noteq..theta..sub.X,Y+1, and that
.theta..sub.X,Y-1.noteq..theta..sub.X,Y+1. Similarly, for Condition
#D1-2, it follows that .theta..sub.X,Y.noteq..theta..sub.X,Y-1,
.theta..sub.X,Y.noteq..theta..sub.X,Y+1, and that
.theta..sub.X,Y-1.noteq..theta..sub.X,Y+1. And, for Condition
#D1-3, it follows that
.theta..sub.X,Y.noteq..theta..sub.X-1,Y.theta..sub.X,Y.noteq..theta..sub.-
X+1,Y, .theta..sub.X,Y.noteq..theta..sub.X,Y-1,
.theta..sub.X,Y.noteq..theta..sub.X,Y+1,
.theta..sub.X-1,Y.noteq..theta..sub.X+1,Y,
.theta..sub.X-1,Y.noteq..theta..sub.X,Y-1,
.theta..sub.X-1,Y.noteq..theta..sub.X,Y+1,
.theta..sub.X+1,Y.noteq..theta..sub.X,Y-1,
.theta..sub.X+1,Y.noteq..theta..sub.X,Y+1, and that
.theta..sub.X,Y-1.noteq..theta..sub.X,Y+1.
[0938] Ideally, a data symbol should satisfy Condition #D1-3.
[0939] FIG. 31 illustrates an example of Condition #D1-3, where
symbol A corresponds to symbol 3100. The symbols are arranged such
that the phase by which switched baseband signal q2 from FIG. 69 is
multiplied differs for symbol 3100, for both neighbouring symbols
thereof in the time domain 3101 and 3102, and for both neighbouring
symbols thereof in the frequency domain 3102 and 3104. Accordingly,
despite received signal quality degradation of symbol 3100 for the
receiver, good signal quality is highly likely for the neighbouring
signals, thus guaranteeing good signal quality after error
correction.
[0940] FIG. 32 illustrates a symbol arrangement obtained through
phase changes under these conditions.
[0941] As evident from FIG. 32, with respect to any data symbol, a
different change in phase is applied to each neighbouring symbol in
the time domain and in the frequency domain. As such, the ability
of the reception device to correct errors may be improved.
[0942] In other words, in FIG. 32, when all neighbouring symbols in
the time domain are data symbols, Condition #D1-1 is satisfied for
all Xs and all Ys.
[0943] Similarly, in FIG. 32, when all neighbouring symbols in the
frequency domain are data symbols, Condition #D1-2 is satisfied for
all Xs and all Ys.
[0944] Similarly, in FIG. 32, when all neighbouring symbols in the
frequency domain are data symbols and all neighbouring symbols in
the time domain are data symbols, Condition #D1-3 is satisfied for
all Xs and all Ys.
[0945] The following discusses the above-described example for a
case where the change of phase is performed on two switched
baseband signals q1 and q2 (see FIG. 68).
[0946] Several phase changing methods are applicable to performing
a change of phase on two switched baseband signals q1 and q2. The
details thereof are explained below.
[0947] Method 1 involves a change in phase of switched baseband
signal q2 as described above, to achieve the change in phase
illustrated by FIG. 32. In FIG. 32, a change of phase having a
period (cycle) of ten is applied to switched baseband signal q2.
However, as described above, in order to satisfy Conditions #D1-1,
#D1-2, and #D1-3, the change in phase applied to switched baseband
signal q2 at each (sub-)carrier changes over time. (Although such
changes are applied in FIG. 32 with a period (cycle) of ten, other
phase changing methods are also applicable.) Then, as shown in FIG.
33, the phase change degree performed on switched baseband signal
q2 produce a constant value that is one-tenth that of the change in
phase performed on switched baseband signal q2. In FIG. 33, for a
period (cycle) (of phase change performed on switched baseband
signal q2) including timestamp $1, the value of the change in phase
performed on switched baseband signal q1 is e.sup.j0. Then, for the
next period (cycle) (of change in phase performed on switched
baseband signal q2) including timestamp $2, the value of the phase
changing degree performed on precoded baseband signal q1 is
e.sup.j.pi./9, and so on.
[0948] The symbols illustrated in FIG. 33 are indicated as
e.sup.j0, for example. This signifies that this symbol is signal q1
from FIG. 26 having undergone a change of phase through
multiplication by e.sup.j0.
[0949] As shown in FIG. 33, the change in phase applied to switched
baseband signal q1 produces a constant value that is one-tenth that
of the change in phase performed on precoded, switched baseband
signal q2 such that the post-phase change value varies with the
number of each period (cycle). (As described above, in FIG. 33, the
value is e.sup.j0 for the first period (cycle), e.sup.j.pi./9 for
the second period (cycle), and so on.)
[0950] As described above, the change in phase performed on
switched baseband signal q2 has a period (cycle) of ten, but the
period (cycle) can be effectively made greater than ten by taking
the degree of phase change applied to switched baseband signal q1
and to switched baseband signal q2 into consideration. Accordingly,
data reception quality may be improved for the reception
device.
[0951] Scheme 2 involves a change in phase of switched baseband
signal q2 as described above, to achieve the change in phase
illustrated by FIG. 32. In FIG. 32, a change of phase having a
period (cycle) of ten is applied to switched baseband signal q2.
However, as described above, in order to satisfy Conditions #D1-1,
#D1-2, and #D1-3, the change in phase applied to switched baseband
signal q2 at each (sub-)carrier changes over time. (Although such
changes are applied in FIG. 32 with a period (cycle) of ten, other
phase changing methods are also applicable.) Then, as shown in FIG.
33, the change in phase performed on switched baseband signal q2
produces a constant value that is one-tenth of that performed on
switched baseband signal q2.
[0952] The symbols illustrated in FIG. 30 are indicated as
e.sup.j0, for example. This signifies that this symbol is switched
baseband signal q1 having undergone a change of phase through
multiplication by e.sup.j0.
[0953] As described above, the change in phase performed on
switched baseband signal q2 has a period (cycle) of ten, but the
period (cycle) can be effectively made greater than ten by taking
the changes in phase applied to switched baseband signal q1 and to
switched baseband signal q2 into consideration. Accordingly, data
reception quality may be improved for the reception device. An
effective way of applying method 2 is to perform a change in phase
on switched baseband signal q1 with a period (cycle) of N and
perform a change in phase on precoded baseband signal q2 with a
period (cycle) of M such that N and M are coprime. As such, by
taking both switched baseband signals q1 and q2 into consideration,
a period (cycle) of N.times.M is easily achievable, effectively
making the period (cycle) greater when N and M are coprime.
[0954] While the above discusses an example of the above-described
phase changing method, the present invention is not limited in this
manner. The change in phase may be performed with respect to the
frequency domain, the time domain, or on time-frequency blocks.
Similar improvement to the data reception quality can be obtained
for the reception device in all cases.
[0955] The same also applies to frames having a configuration other
than that described above, where pilot symbols (SP symbols) and
symbols transmitting control information are inserted among the
data symbols. The details of the change in phase in such
circumstances are as follows.
[0956] FIGS. 47A and 47B illustrate the frame configuration of
modulated signals (switched baseband signals q1 and q2) z1 or z1'
and z2' in the time-frequency domain. FIG. 47A illustrates the
frame configuration of modulated signal (switched baseband signal
q1) z1 or z1' while FIG. 47B illustrates the frame configuration of
modulated signal (switched baseband signal q2) z2'. In FIGS. 47A
and 47B, 4701 marks pilot symbols while 4702 marks data symbols.
The data symbols 4702 are symbols on which switching or switching
and change in phase have been performed.
[0957] FIGS. 47A and 47B, like FIG. 69, indicate the arrangement of
symbols when a change in phase is applied to switched baseband
signal q2 (while no change in phase is performed on switched
baseband signal q1). (Although FIG. 69 illustrates a change in
phase with respect to the time domain, switching time t with
carrier fin FIG. 69 corresponds to a change in phase with respect
to the frequency domain. In other words, replacing (t) with (t, f)
where t is time and f is frequency corresponds to performing a
change of phase on time-frequency blocks.) Accordingly, the
numerical values indicated in FIGS. 47A and 47B for each of the
symbols are the values of switched baseband signal q2 after the
change in phase. No values are given for the symbols of switched
baseband signal q1 (z1) from FIGS. 47A and 47B as no change in
phase is performed thereon.
[0958] The important point of FIGS. 47A and 47B is that the change
in phase performed on the data symbols of switched baseband signal
q2, i.e., on symbols having undergone precoding or precoding and
switching. (The symbols under discussion, being precoded, actually
include both symbols s1 and s2.) Accordingly, no change in phase is
performed on the pilot symbols inserted in z2'.
[0959] FIGS. 48A and 48B illustrate the frame configuration of
modulated signals (switched baseband signals q1 and q2) z1 or z1'
and z2' in the time-frequency domain. FIG. 48A illustrates the
frame configuration of modulated signal (switched baseband signal
q1) z1 or z1' while FIG. 48B illustrates the frame configuration of
modulated signal (switched baseband signal q2) z2'. In FIGS. 48A
and 48B, 4701 marks pilot symbols while 4702 marks data symbols.
The data symbols 4702 are symbols on which precoding or precoding
and a change in phase have been performed.
[0960] FIGS. 48A and 48B indicate the arrangement of symbols when a
change in phase is applied to switched baseband signal q1 and to
switched baseband signal q2. Accordingly, the numerical values
indicated in FIGS. 48A and 48B for each of the symbols are the
values of switched baseband signals q1 and q2 after a change in
phase.
[0961] The important point of FIGS. 48A and 48B is that the change
in phase is performed on the data symbols of switched baseband
signal q1, that is, on the precoded or precoded and switched
symbols thereof, and on the data symbols of switched baseband
signal q2, that is, on the precoded or precoded and switched
symbols thereof. (The symbols under discussion, being precoded,
actually include both symbols s1 and s2.) Accordingly, no change in
phase is performed on the pilot symbols inserted in z1', nor on the
pilot symbols inserted in z2'.
[0962] FIGS. 49A and 49B illustrate the frame configuration of
modulated signals (switched baseband signals q1 and q2) z1 or z1'
and z2' in the time-frequency domain. FIG. 49A illustrates the
frame configuration of modulated signal (switched baseband signal
q1) z1 or z1' while FIG. 49B illustrates the frame configuration of
modulated signal (switched baseband signal q2) z2'. In FIGS. 49A
and 49B, 4701 marks pilot symbols, 4702 marks data symbols, and
4901 marks null symbols for which the in-phase component of the
baseband signal I=0 and the quadrature component Q=0. As such, data
symbols 4702 are symbols on which precoding or precoding and a
change in phase have been performed. FIGS. 49A and 49B differ from
FIGS. 47A and 47B in the configuration scheme for symbols other
than data symbols. The times and carriers at which pilot symbols
are inserted into modulated signal z1' are null symbols in
modulated signal z2'. Conversely, the times and carriers at which
pilot symbols are inserted into modulated signal z2' are null
symbols in modulated signal z1'.
[0963] FIGS. 49A and 49B, like FIG. 69, indicate the arrangement of
symbols when a change in phase is applied to switched baseband
signal q2 (while no change in phase is performed on switched
baseband signal q1). (Although FIG. 69 illustrates a change in
phase with respect to the time domain, switching time t with
carrier fin FIG. 6 corresponds to a change in phase with respect to
the frequency domain. In other words, replacing (t) with (t, f)
where t is time and f is frequency corresponds to performing a
change of phase on time-frequency blocks.) Accordingly, the
numerical values indicated in FIGS. 49A and 49B for each of the
symbols are the values of switched baseband signal q2 after the
change in phase. No values are given for the symbols of switched
baseband signal q1 from FIGS. 49A and 49B as no change in phase is
performed thereon.
[0964] The important point of FIGS. 49A and 49B is that the change
in phase performed on the data symbols of switched baseband signal
q2, i.e., on symbols having undergone precoding or precoding and
switching. (The symbols under discussion, being precoded, actually
include both symbols s1 and s2.) Accordingly, no change in phase is
performed on the pilot symbols inserted in z2'.
[0965] FIGS. 50A and 50B illustrate the frame configuration of
modulated signals (switched baseband signals q1 and q2) z1 or z1'
and z2' in the time-frequency domain. FIG. 50A illustrates the
frame configuration of modulated signal (switched baseband signal
q1) z1 or z1' while FIG. 50B illustrates the frame configuration of
modulated signal (switched baseband signal q2) z2'. In FIGS. 50A
and 50B, 4701 marks pilot symbols, 4702 marks data symbols, and
4901 marks null symbols for which the in-phase component of the
baseband signal I=0 and the quadrature component Q=0. As such, data
symbols 4702 are symbols on which precoding or precoding and a
change in phase have been performed. FIGS. 50A and 50B differ from
FIGS. 48A and 48B in the configuration scheme for symbols other
than data symbols. The times and carriers at which pilot symbols
are inserted into modulated signal z1' are null symbols in
modulated signal z2'. Conversely, the times and carriers at which
pilot symbols are inserted into modulated signal z2' are null
symbols in modulated signal z1'.
[0966] FIGS. 50A and 50B indicate the arrangement of symbols when a
change in phase is applied to switched baseband signal q1 and to
switched baseband signal q2. Accordingly, the numerical values
indicated in FIGS. 50A and 50B for each of the symbols are the
values of switched baseband signals q1 and q2 after a change in
phase.
[0967] The important point of FIGS. 50A and 50B is that a change in
phase is performed on the data symbols of switched baseband signal
q1, that is, on the precoded or precoded and switched symbols
thereof, and on the data symbols of switched baseband signal q2,
that is, on the precoded or precoded and switched symbols thereof.
(The symbols under discussion, being precoded, actually include
both symbols s1 and s2.) Accordingly, no change in phase is
performed on the pilot symbols inserted in z1', nor on the pilot
symbols inserted in z2'.
[0968] FIG. 51 illustrates a sample configuration of a transmission
device generating and transmitting modulated signal having the
frame configuration of FIGS. 47A, 47B, 49A, and 49B. Components
thereof performing the same operations as those of FIG. 4 use the
same reference symbols thereas. FIG. 51 does not include a baseband
signal switcher as illustrated in FIGS. 67 and 70. However, FIG. 51
may also include a baseband signal switcher between the weighting
unit and phase changer, much like FIGS. 67 and 70.
[0969] In FIG. 51, the weighting units 308A and 308B, phase changer
317B, and baseband signal switcher only operate at times indicated
by the frame configuration signal 313 as corresponding to data
symbols.
[0970] In FIG. 51, a pilot symbol generator 5101 (that also
generates null symbols) outputs baseband signals 5102A and 5102B
for a pilot symbol whenever the frame configuration signal 313
indicates a pilot symbol (and a null symbol).
[0971] Although not indicated in the frame configurations from
FIGS. 47A through 50B, when precoding (and phase rotation) is not
performed, such as when transmitting a modulated signal using only
one antenna (such that the other antenna transmits no signal) or
when using a space-time coding transmission method (particularly,
space-time block coding) to transmit control information symbols,
then the frame configuration signal 313 takes control information
symbols 5104 and control information 5103 as input. When the frame
configuration signal 313 indicates a control information symbol,
baseband signals 5102A and 5102B thereof are output.
[0972] Wireless units 310A and 310B of FIG. 51 take a plurality of
baseband signals as input and select a desired baseband signal
according to the frame configuration signal 313. The wireless units
310A and 310B then apply OFDM signal processing and output
modulated signals 311A and 311B conforming to the frame
configuration.
[0973] FIG. 52 illustrates a sample configuration of a transmission
device generating and transmitting modulated signal having the
frame configuration of FIGS. 48A, 48B, 50A, and 50B. Components
thereof performing the same operations as those of FIGS. 4 and 51
use the same reference symbols thereas. FIG. 52 features an
additional phase changer 317A that only operates when the frame
configuration signal 313 indicates a data symbol. At all other
times, the operations are identical to those explained for FIG. 51.
FIG. 52 does not include a baseband signal switcher as illustrated
in FIGS. 67 and 70. However, FIG. 52 may also include a baseband
signal switcher between the weighting unit and phase changer, much
like FIGS. 67 and 70.
[0974] FIG. 53 illustrates a sample configuration of a transmission
device that differs from that of FIG. 51. FIG. 53 does not include
a baseband signal switcher as illustrated in FIGS. 67 and 70.
However, FIG. 53 may also include a baseband signal switcher
between the weighting unit and phase changer, much like FIGS. 67
and 70. The following describes the points of difference. As shown
in FIG. 53, phase changer 317B takes a plurality of baseband
signals as input. Then, when the frame configuration signal 313
indicates a data symbol, phase changer 317B performs the change in
phase on precoded baseband signal 316B. When frame configuration
signal 313 indicates a pilot symbol (or null symbol) or a control
information symbol, phase changer 317B pauses phase changing
operations such that the symbols of the baseband signal are output
as-is. (This may be interpreted as performing forced rotation
corresponding to e.sup.j0.)
[0975] A selector 5301 takes the plurality of baseband signals as
input and selects a baseband signal having a symbol indicated by
the frame configuration signal 313 for output.
[0976] FIG. 54 illustrates a sample configuration of a transmission
device that differs from that of FIG. 52. FIG. 54 does not include
a baseband signal switcher as illustrated in FIGS. 67 and 70.
However, FIG. 54 may also include a baseband signal switcher
between the weighting unit and phase changer, much like FIGS. 67
and 70. The following describes the points of difference. As shown
in FIG. 54, phase changer 317B takes a plurality of baseband
signals as input. Then, when the frame configuration signal 313
indicates a data symbol, phase changer 317B performs the change in
phase on precoded baseband signal 316B. When frame configuration
signal 313 indicates a pilot symbol (or null symbol) or a control
information symbol, phase changer 317B pauses phase changing
operations such that the symbols of the baseband signal are output
as-is. (This may be interpreted as performing forced rotation
corresponding to e.sup.j0.)
[0977] Similarly, as shown in FIG. 54, phase changer 5201 takes a
plurality of baseband signals as input. Then, when the frame
configuration signal 313 indicates a data symbol, phase changer
5201 performs the change in phase on precoded baseband signal 309A.
When frame configuration signal 313 indicates a pilot symbol (or
null symbol) or a control information symbol, phase changer 5201
pauses phase changing operations such that the symbols of the
baseband signal are output as-is. (This may be interpreted as
performing forced rotation corresponding to e.sup.j0.)
[0978] The above explanations are given using pilot symbols,
control symbols, and data symbols as examples. However, the present
invention is not limited in this manner. When symbols are
transmitted using methods other than precoding, such as
single-antenna transmission or transmission using space-time block
coding, the absence of change in phase is important. Conversely,
performing the change of phase on symbols that have been precoded
is the key point of the present invention.
[0979] Accordingly, a characteristic feature of the present
invention is that the change in phase is not performed on all
symbols within the frame configuration in the time-frequency
domain, but only performed on baseband signals that have been
precoded and have undergone switching.
[0980] The following describes a scheme for regularly changing the
phase when encoding is performed using block codes as described in
Non-Patent Literature 12 through 15, such as QC LDPC Codes (not
only QC-LDPC but also LDPC codes may be used), concatenated LDPC
and BCH codes, Turbo codes or Duo-Binary Turbo Codes using tail
biting, and so on. The following example considers a case where two
streams s1 and s2 are transmitted. When encoding has been performed
using block codes and control information and the like is not
necessary, the number of bits making up each encoded block matches
the number of bits making up each block code (control information
and so on described below may yet be included). When encoding has
been performed using block codes or the like and control
information or the like (e.g., CRC transmission parameters) is
required, then the number of bits making up each encoded block is
the sum of the number of bits making up the block codes and the
number of bits making up the information.
[0981] FIG. 34 illustrates the varying numbers of symbols and slots
needed in two coded blocks when block codes are used. Unlike FIGS.
69 and 70, for example, FIG. 34 illustrates the varying numbers of
symbols and slots needed in each encoded block when block codes are
used when, for example, two streams s1 and s2 are transmitted as
indicated in FIG. 4, with an encoder and distributor. (Here, the
transmission method may be any single-carrier method or
multi-carrier method such as OFDM.)
[0982] As shown in FIG. 34, when block codes are used, there are
6000 bits making up a single encoded block. In order to transmit
these 6000 bits, the number of required symbols depends on the
modulation method, being 3000 for QPSK, 1500 for 16-QAM, and 1000
for 64-QAM.
[0983] Then, given that the above-described transmission device
transmits two streams simultaneously, 1500 of the aforementioned
3000 symbols needed when the modulation method is QPSK are assigned
to s1 and the other 1500 symbols are assigned to s2. As such, 1500
slots for transmitting the 1500 symbols (hereinafter, slots) are
required for each of s1 and s2.
[0984] By the same reasoning, when the modulation method is 16-QAM,
750 slots are needed to transmit all of the bits making up two
encoded blocks, and when the modulation method is 64-QAM, 500 slots
are needed to transmit all of the bits making up the two encoded
blocks.
[0985] The following describes the relationship between the
above-defined slots and the phase of multiplication, as pertains to
methods for a regular change of phase.
[0986] Here, five different phase changing values (or phase
changing sets) are assumed as having been prepared for use in the
method for a regular change of phase. That is, the phase changer of
the above-described transmission device uses five phase changing
values (or phase changing sets) to achieve the period (cycle) of
five. (As in FIG. 69, five phase changing values are needed in
order to perform a change of phase having a period (cycle) of five
on switched baseband signal q2 only. Similarly, in order to perform
the change in phase on both switched baseband signals q1 and q2,
two phase changing values are needed for each slot. These two phase
changing values are termed a phase changing set. Accordingly, here,
in order to perform a change of phase having a period (cycle) of
five, five such phase changing sets should be prepared). The five
phase changing values (or phase changing sets) are expressed as
PHASE[0], PHASE[1], PHASE[2], PHASE[3], and PHASE [4].
[0987] For the above-described 1500 slots needed to transmit the
6000 bits making up a single encoded block when the modulation
method is QPSK, PHASE[0] is used on 300 slots, PHASE[1] is used on
300 slots, PHASE[2] is used on 300 slots, PHASE[3] is used on 300
slots, and PHASE[4] is used on 300 slots. This is due to the fact
that any bias in phase usage causes great influence to be exerted
by the more frequently used phase, and that the reception device is
dependent on such influence for data reception quality.
[0988] Furthermore, for the above-described 750 slots needed to
transmit the 6000 bits making up a single coded block when the
modulation scheme is 16-QAM, PHASE[0] is used on 150 slots,
PHASE[1] is used on 150 slots, PHASE[2] is used on 150 slots,
PHASE[3] is used on 150 slots, and PHASE[4] is used on 150
slots.
[0989] Further still, for the above-described 500 slots needed to
transmit the 6000 bits making up a single encoded block when the
modulation method is 64-QAM, PHASE[0] is used on 100 slots,
PHASE[1] is used on 100 slots, PHASE[2] is used on 100 slots,
PHASE[3] is used on 100 slots, and PHASE[4] is used on 100
slots.
[0990] As described above, a scheme for a regular change of phase
requires the preparation of N phase changing values (or phase
changing sets) (where the N different phases are expressed as
PHASE[0], PHASE[1], PHASE[2] . . . PHASE[N-2], PHASE[N-1]). As
such, in order to transmit all of the bits making up a single coded
block, PHASE[0] is used on K.sub.0 slots, PHASE[1] is used on
K.sub.1 slots, PHASE[i] is used on K.sub.i slots (where i=0, 1, 2 .
. . N-1), and PHASE[N-1] is used on KN-1 slots, such that Condition
#D1-4 is met.
(Condition #D1-4)
[0991] K.sub.0=K.sub.1 . . . =K.sub.i= . . . K.sub.N-1. That is,
K.sub.a=K.sub.b (for .A-inverted.a and .A-inverted.b where a, b,=0,
1, 2 . . . N-1, a.noteq.b).
[0992] Then, when a communication system that supports multiple
modulation methods selects one such supported method for use,
Condition #D1-4 must be met for the supported modulation
method.
[0993] However, when multiple modulation methods are supported,
each such modulation method typically uses symbols transmitting a
different number of bits per symbols (though some may happen to use
the same number), Condition #D1-4 may not be satisfied for some
modulation methods. In such a case, the following condition applies
instead of Condition #D1-4.
(Condition #D1-5)
[0994] The difference between K.sub.a and K.sub.b satisfies 0 or 1.
That is, |K.sub.a-K.sub.b| satisfies 0 or 1 (.A-inverted.a,
.A-inverted.b, where a, b=0, 1, 2 . . . N-1, a.noteq.b)
[0995] FIG. 35 illustrates the varying numbers of symbols and slots
needed in two coded blocks when block codes are used. FIG. 35
illustrates the varying numbers of symbols and slots needed in each
encoded block when block codes are used when, for example, two
streams s1 and s2 are transmitted as indicated by the transmission
device from FIG. 67 and FIG. 70, and the transmission device has
two encoders. (Here, the transmission method may be any
single-carrier method or multi-carrier method such as OFDM.)
[0996] As shown in FIG. 35, when block codes are used, there are
6000 bits making up a single encoded block. In order to transmit
these 6000 bits, the number of required symbols depends on the
modulation method, being 3000 for QPSK, 1500 for 16-QAM, and 1000
for 64-QAM.
[0997] The transmission device from FIG. 67 and the transmission
device from FIG. 70 each transmit two streams at once, and have two
encoders. As such, the two streams each transmit different code
blocks. Accordingly, when the modulation method is QPSK, two
encoded blocks drawn from s1 and s2 are transmitted within the same
interval, e.g., a first encoded block drawn from s1 is transmitted,
then a second encoded block drawn from s2 is transmitted. As such,
3000 slots are needed in order to transmit the first and second
encoded blocks.
[0998] By the same reasoning, when the modulation scheme is 16-QAM,
1500 slots are needed to transmit all of the bits making up the two
coded blocks, and when the modulation scheme is 64-QAM, 1000 slots
are needed to transmit all of the bits making up the two coded
blocks
[0999] The following describes the relationship between the
above-defined slots and the phase of multiplication, as pertains to
methods for a regular change of phase.
[1000] Here, five different phase changing values (or phase
changing sets) are assumed as having been prepared for use in the
method for a regular change of phase. That is, the phase changer of
the transmission device from FIG. 67 and FIG. 70 uses five phase
changing values (or phase changing sets) to achieve the period
(cycle) of five. (As in FIG. 69, five phase changing values are
needed in order to perform a change of phase having a period
(cycle) of five on switched baseband signal q2 only. Similarly, in
order to perform the change in phase on both switched baseband
signals q1 and q2, two phase changing values are needed for each
slot. These two phase changing values are termed a phase changing
set. Accordingly, here, in order to perform a change of phase
having a period (cycle) of five, five such phase changing sets
should be prepared). The five phase changing values (or phase
changing sets) are expressed as PHASE[0], PHASE[1], PHASE[2],
PHASE[3], and PHASE [4].
[1001] For the above-described 3000 slots needed to transmit the
6000.times.2 bits making up the two encoded blocks when the
modulation method is QPSK, PHASE[0] is used on 600 slots, PHASE[1]
is used on 600 slots, PHASE[2] is used on 600 slots, PHASE[3] is
used on 600 slots, and PHASE[4] is used on 600 slots. This is due
to the fact that any bias in phase usage causes great influence to
be exerted by the more frequently used phase, and that the
reception device is dependent on such influence for data reception
quality.
[1002] Furthermore, in order to transmit the first coded block,
PHASE[0] is used on slots 600 times, PHASE[1] is used on slots 600
times, PHASE[2] is used on slots 600 times, PHASE[3] is used on
slots 600 times, and PHASE[4] is used on slots 600 times.
Furthermore, in order to transmit the second coded block, PHASE[0]
is used on slots 600 times, PHASE[1] is used on slots 600 times,
PHASE[2] is used on slots 600 times, PHASE[3] is used on slots 600
times, and PHASE[4] is used on slots 600 times.
[1003] Similarly, for the above-described 1500 slots needed to
transmit the 6000.times.2 bits making up the two encoded blocks
when the modulation method is 16-QAM, PHASE[0] is used on 300
slots, PHASE[1] is used on 300 slots, PHASE[2] is used on 300
slots, PHASE[3] is used on 300 slots, and PHASE[4] is used on 300
slots.
[1004] Furthermore, in order to transmit the first coded block,
PHASE[0] is used on slots 300 times, PHASE[1] is used on slots 300
times, PHASE[2] is used on slots 300 times, PHASE[3] is used on
slots 300 times, and PHASE[4] is used on slots 300 times.
Furthermore, in order to transmit the second coded block, PHASE[0]
is used on slots 300 times, PHASE[1] is used on slots 300 times,
PHASE[2] is used on slots 300 times, PHASE[3] is used on slots 300
times, and PHASE[4] is used on slots 300 times.
[1005] Similarly, for the above-described 1000 slots needed to
transmit the 6000.times.2 bits making up the two coded blocks when
the modulation scheme is 64-QAM, PHASE[0] is used on 200 slots,
PHASE[1] is used on 200 slots, PHASE[2] is used on 200 slots,
PHASE[3] is used on 200 slots, and PHASE[4] is used on 200
slots.
[1006] Furthermore, in order to transmit the first coded block,
PHASE[0] is used on slots 200 times, PHASE[1] is used on slots 200
times, PHASE[2] is used on slots 200 times, PHASE[3] is used on
slots 200 times, and PHASE[4] is used on slots 200 times.
Furthermore, in order to transmit the second coded block, PHASE[0]
is used on slots 200 times, PHASE[1] is used on slots 200 times,
PHASE[2] is used on slots 200 times, PHASE[3] is used on slots 200
times, and PHASE[4] is used on slots 200 times.
[1007] As described above, a method for a regular change of phase
requires the preparation of N phase changing values (or phase
changing sets) (where the N different phases are expressed as
PHASE[0], PHASE[1], PHASE[2] . . . PHASE[N-2], PHASE[N-2]). As
such, in order to transmit all of the bits making up a single
encoded block, PHASE[0] is used on K.sub.0 slots, PHASE[1] is used
on K.sub.1 slots, PHASE[i] is used on K.sub.i slots (where i=0, 1,
2 . . . N-1), and PHASE[N-1] is used on K.sub.N-1 slots, such that
Condition #D1-6 is met.
(Condition #D1-6)
[1008] K.sub.0=K.sub.1 . . . =K.sub.i= . . . K.sub.N-1. That is,
K.sub.a=K.sub.b (for .A-inverted.a and .A-inverted.b where a, b,=0,
1, 2 . . . N-1, a.noteq.b). Further, in order to transmit all of
the bits making up the first coded block, PHASE[0] is used K0,1
times, PHASE[1] is used K1,1 times, PHASE[i] is used times (where
i=0, 1, 2 . . . N-1), and PHASE[N-1] is used KN-1,1 times, such
that Condition #D1-7 is met.
(Condition #D1-7)
[1008] [1009] K.sub.0,1=K.sub.1,1= . . . K.sub.i,1= . . .
K.sub.N-1,1. That is, K.sub.a,1=K.sub.b,1 (.A-inverted.a and
.A-inverted.b where a, b,=0, 1, 2 . . . N-1, a.noteq.b).
Furthermore, in order to transmit all of the bits making up the
second coded block, PHASE[0] is used K.sub.0,2 times, PHASE[1] is
used K.sub.1,2 times, PHASE[i] is used K.sub.i,2 times (where i=0,
1, 2 . . . N-1), and PHASE[N-1] is used K.sub.N-1,2 times, such
that Condition #D1-8 is met.
(Condition #D1-8)
[1009] [1010] K.sub.0,2=K.sub.1,2= . . . k.sub.i,2= . . .
K.sub.N-1,2. That is, K.sub.a,2=K.sub.b,2 (.A-inverted.a and
.A-inverted.b where a, b,=0, 1, 2 . . . N-1, a.noteq.b).
[1011] Then, when a communication system that supports multiple
modulation methods selects one such supported method for use,
Condition #D1-6 Condition #D1-7, and Condition #D1-8 must be met
for the supported modulation method.
[1012] However, when multiple modulation methods are supported,
each such modulation method typically uses symbols transmitting a
different number of bits per symbols (though some may happen to use
the same number), Condition #D1-6 Condition #D1-7, and Condition
#D1-8 may not be satisfied for some modulation methods. In such a
case, the following conditions apply instead of Condition #D1-6
Condition #D1-7, and Condition #D1-8.
(Condition #D1-9)
[1013] The difference between Ka and Kb satisfies 0 or 1. That is,
|K.sub.a-K.sub.b| satisfies 0 or 1 (.A-inverted.a, .A-inverted.b,
where a, b=0, 1, 2 . . . N-1, a.noteq.b)
(Condition #D1-10)
[1013] [1014] The difference between K.sub.a,1 and K.sub.b,1
satisfies 0 or 1. That is, |K.sub.a,1-K.sub.b,1| satisfies 0 or 1
(.A-inverted.a, .A-inverted.b, where a, b=0, 1, 2 . . . N-1,
a.noteq.b)
(Condition #D1-11)
[1014] [1015] The difference between K.sub.a,2 and K.sub.b,2
satisfies 0 or 1. That is, |K.sub.a,2-K.sub.b,2| satisfies 0 or 1
(.A-inverted.a, .A-inverted.b, where a, b=0, 1, 2 . . . N-1,
a.noteq.b)
[1016] As described above, bias among the phases being used to
transmit the encoded blocks is removed by creating a relationship
between the encoded block and the phase of multiplication. As such,
data reception quality may be improved for the reception
device.
[1017] As described above, N phase changing values (or phase
changing sets) are needed in order to perform a change of phase
having a period (cycle) of N with the method for the regular change
of phase. As such, N phase changing values (or phase changing sets)
PHASE[0], PHASE[1], PHASE[2] . . . PHASE[N-2], and PHASE[N-1] are
prepared. However, schemes exist for ordering the phases in the
stated order with respect to the frequency domain. No limitation is
intended in this regard. The N phase changing values (or phase
changing sets) PHASE[0], PHASE[1], PHASE[2] . . . PHASE[N-2], and
PHASE[N-1] may also change the phases of blocks in the time domain
or in the time-frequency domain to obtain a symbol arrangement.
Although the above examples discuss a phase changing method with a
period (cycle) of N, the same effects are obtainable using N phase
changing values (or phase changing sets) at random. That is, the N
phase changing values (or phase changing sets) need not always have
regular periodicity. As long as the above-described conditions are
satisfied, great quality data reception improvements are realizable
for the reception device.
[1018] Furthermore, given the existence of modes for spatial
multiplexing MIMO methods, MIMO methods using a fixed precoding
matrix, space-time block coding methods, single-stream
transmission, and methods using a regular change of phase, the
transmission device (broadcaster, base station) may select any one
of these transmission methods.
[1019] As described in Non-Patent Literature 3, spatial
multiplexing MIMO methods involve transmitting signals s1 and s2,
which are mapped using a selected modulation method, on each of two
different antennas. MIMO methods using a fixed precoding matrix
involve performing precoding only (with no change in phase).
Further, space-time block coding methods are described in
Non-Patent Literature 9, 16, and 17. Single-stream transmission
methods involve transmitting signal s1, mapped with a selected
modulation method, from an antenna after performing predetermined
processing.
[1020] Schemes using multi-carrier transmission such as OFDM
involve a first carrier group made up of a plurality of carriers
and a second carrier group made up of a plurality of carriers
different from the first carrier group, and so on, such that
multi-carrier transmission is realized with a plurality of carrier
groups. For each carrier group, any of spatial multiplexing MIMO
methods, MIMO methods using a fixed precoding matrix, space-time
block coding methods, single-stream transmission, and methods using
a regular change of phase may be used. In particular, methods using
a regular change of phase on a selected (sub-)carrier group are
preferably used to realize the above.
[1021] Although the present description describes the present
Embodiment as a transmission device applying precoding, baseband
switching, and change in phase, all of these may be variously
combined. In particular, the phase changer discussed for the
present Embodiment may be freely combined with the change in phase
discussed in all other Embodiments.
Embodiment D2
[1022] The present Embodiment describes a phase change
initialization method for the regular change of phase described
throughout the present description. This initialization method is
applicable to the transmission device from FIG. 4 when using a
multi-carrier method such as OFDM, and to the transmission devices
of FIGS. 67 and 70 when using a single encoder and distributor,
similar to FIG. 4.
[1023] The following is also applicable to a method of regularly
changing the phase when encoding is performed using block codes as
described in Non-Patent Literature 12 through 15, such as QC LDPC
Codes (not only QC-LDPC but also LDPC codes may be used),
concatenated LDPC and BCH codes, Turbo codes or Duo-Binary Turbo
Codes using tail biting, and so on.
[1024] The following example considers a case where two streams s1
and s2 are transmitted. When encoding has been performed using
block codes and control information and the like is not necessary,
the number of bits making up each encoded block matches the number
of bits making up each block code (control information and so on
described below may yet be included). When encoding has been
performed using block codes or the like and control information or
the like (e.g., CRC transmission parameters) is required, then the
number of bits making up each encoded block is the sum of the
number of bits making up the block codes and the number of bits
making up the information.
[1025] FIG. 34 illustrates the varying numbers of symbols and slots
needed in each coded block when block codes are used. FIG. 34
illustrates the varying numbers of symbols and slots needed in each
encoded block when block codes are used when, for example, two
streams s1 and s2 are transmitted as indicated by the
above-described transmission device, and the transmission device
has only one encoder. (Here, the transmission method may be any
single-carrier method or multi-carrier method such as OFDM.)
[1026] As shown in FIG. 34, when block codes are used, there are
6000 bits making up a single encoded block. In order to transmit
these 6000 bits, the number of required symbols depends on the
modulation method, being 3000 for QPSK, 1500 for 16-QAM, and 1000
for 64-QAM.
[1027] Then, given that the above-described transmission device
transmits two streams simultaneously, 1500 of the aforementioned
3000 symbols needed when the modulation method is QPSK are assigned
to s1 and the other 1500 symbols are assigned to s2. As such, 1500
slots for transmitting the 1500 symbols (hereinafter, slots) are
required for each of s1 and s2.
[1028] By the same reasoning, when the modulation scheme is 16-QAM,
750 slots are needed to transmit all of the bits making up each
coded block, and when the modulation scheme is 64-QAM, 500 slots
are needed to transmit all of the bits making up each coded
block.
[1029] The following describes a transmission device transmitting
modulated signals having a frame configuration illustrated by FIGS.
71A and 71B. FIG. 71A illustrates a frame configuration for
modulated signal z1' or z1 (transmitted by antenna 312A) in the
time and frequency domains. Similarly, FIG. 71B illustrates a frame
configuration for modulated signal z2 (transmitted by antenna 312B)
in the time and frequency domains. Here, the frequency (band) used
by modulated signal z1' or z1 and the frequency (band) used for
modulated signal z2 are identical, carrying modulated signals z1'
or z1 and z2 at the same time.
[1030] As shown in FIG. 71A, the transmission device transmits a
preamble (control symbol) during interval A. The preamble is a
symbol transmitting control information for another party. In
particular, this preamble includes information on the modulation
method used to transmit a first and a second encoded block. The
transmission device transmits the first encoded block during
interval B. The transmission device then transmits the second
encoded block during interval C.
[1031] Further, the transmission device transmits a preamble
(control symbol) during interval D. The preamble is a symbol
transmitting control information for another party. In particular,
this preamble includes information on the modulation method used to
transmit a third or fourth encoded block and so on. The
transmission device transmits the third encoded block during
interval E. The transmission device then transmits the fourth
encoded block during interval D.
[1032] Also, as shown in FIG. 71B, the transmission device
transmits a preamble (control symbol) during interval A. The
preamble is a symbol transmitting control information for another
party. In particular, this preamble includes information on the
modulation method used to transmit a first and a second encoded
block. The transmission device transmits the first encoded block
during interval B. The transmission device then transmits the
second encoded block during interval C.
[1033] Further, the transmission device transmits a preamble
(control symbol) during interval D. The preamble is a symbol
transmitting control information for another party. In particular,
this preamble includes information on the modulation method used to
transmit a third or fourth encoded block and so on. The
transmission device transmits the third encoded block during
interval E. The transmission device then transmits the fourth
encoded block during interval D.
[1034] FIG. 72 indicates the number of slots used when transmitting
the encoded blocks from FIG. 34, specifically using 16-QAM as the
modulation method for the first encoded block. Here, 750 slots are
needed to transmit the first encoded block.
[1035] Similarly, FIG. 72 also indicates the number of slots used
to transmit the second encoded block, using QPSK as the modulation
method therefor. Here, 1500 slots are needed to transmit the second
encoded block.
[1036] FIG. 73 indicates the slots used when transmitting the
encoded blocks from FIG. 34, specifically using QPSK as the
modulation method for the third encoded block. Here, 1500 slots are
needed to transmit the encoded block.
[1037] As explained throughout this description, modulated signal
z1, i.e., the modulated signal transmitted by antenna 312A, does
not undergo a change in phase, while modulated signal z2, i.e., the
modulated signal transmitted by antenna 312B, does undergo a change
in phase. The following phase changing method is used for FIGS. 72
and 73.
[1038] Before the change in phase can occur, seven different phase
changing values must prepared. The seven phase changing values are
labeled #0, #1, #2, #3, #4, #5, and #6. The change in phase is
regular and periodic. In other words, the phase changing values are
applied regularly and periodically, such that the order is #0, #1,
#2, #3, #4, #5, #6, #0, #1, #2, #3, #4, #5, #6, #0, #1, #2, #3, #4,
#5, #6 and so on.
[1039] As shown in FIG. 72, given that 750 slots are needed for the
first coded block, phase changing value #0 is used initially, such
that #0, #1, #2, #3, #4, #5, #6, #0, #1, #2 . . . #3, #4, #5, #6
are used in succession, with the 750th slot using #0 at the final
position.
[1040] The change in phase is then applied to each slot for the
second encoded block. The present description assumes multi-cast
transmission and broadcasting applications. As such, a receiving
terminal may have no need for the first encoded block and extract
only the second encoded block. In such circumstances, given that
the final slot used for the first encoded block uses phase changing
value #0, the initial phase changing value used for the second
encoded block is #1. As such, the following methods are
conceivable:
[1041] (a): The aforementioned terminal monitors the transmission
of the first encoded block, i.e., monitors the pattern of the phase
changing values through the final slot used to transmit the first
encoded block, and then estimates the phase changing value used for
the initial slot of the second encoded block;
[1042] (b): (a) does not occur, and the transmission device
transmits information on the phase changing values in use at the
initial slot of the second encoded block. Scheme (a) leads to
greater energy consumption by the terminal due to the need to
monitor the transmission of the first encoded block. However,
scheme (b) leads to reduced data transmission efficiency.
[1043] Accordingly, there is a need to improve the phase changing
value allocation described above. Consider a method in which the
phase changing value used to transmit the initial slot of each
encoded block is fixed. Thus, as indicated in FIG. 72, the phase
changing value used to transmit the initial slot of the second
encoded block and the phase changing value used to transmit the
initial slot of the first encoded block are identical, being
#0.
[1044] Similarly, as indicated in FIG. 73, the phase changing value
used to transmit the initial slot of the third encoded block is not
#3, but is instead identical to the phase changing value used to
transmit the initial slot of the first and second encoded blocks,
being #0.
[1045] As such, the problems accompanying both methods (a) and (b)
described above can be constrained while retaining the effects
thereof.
[1046] In the present Embodiment, the method used to initialize the
phase changing value for each encoded block, i.e., the phase
changing value used for the initial slot of each encoded block, is
fixed so as to be #0. However, other methods may also be used for
single-frame units. For example, the phase changing value used for
the initial slot of a symbol transmitting information after the
preamble or control symbol has been transmitted may be fixed at
#0.
Embodiment D3
[1047] The above-described Embodiments discuss a weighting unit
using a precoding matrix expressed in complex numbers for
precoding. However, the precoding matrix may also be expressed in
real numbers.
[1048] That is, suppose that two baseband signals s1(i) and s2(i)
(where i is time or frequency) have been mapped (using a modulation
scheme), and precoded to obtained precoded baseband signals z1(i)
and z2(i). As such, mapped baseband signal s1(i) has an in-phase
component of I.sub.s1(i) and a quadrature component of Q.sub.s1(i),
and mapped baseband signal s2(i) has an in-phase component of
I.sub.s2(i) and a quadrature component of Q.sub.s2(i), while
precoded baseband signal z1(i) has an in-phase component of Iz1(i)
and a quadrature component of Q.sub.z1(i), and precoded baseband
signal z2(i) has an in-phase component of I.sub.z2(i) and a
quadrature component of Q.sub.z2(i), which gives the following
precoding matrix H.sub.r when all values are real numbers.
[ Math . .times. 76 ] ##EQU00048## ( I z .times. .times. 1
.function. ( i ) Q z .times. .times. 1 .function. ( i ) I z .times.
.times. 2 .function. ( i ) Q z .times. .times. 2 .function. ( i ) )
= H r .function. ( I s .times. .times. 1 .function. ( i ) Q s
.times. .times. 1 .function. ( i ) I s .times. .times. 2 .function.
( i ) Q s .times. .times. 2 .function. ( i ) ) ( formula .times.
.times. 76 ) ##EQU00048.2##
[1049] Precoding matrix H.sub.r may also be expressed as follows,
where all values are real numbers.
[ Math . .times. 77 ] ##EQU00049## H r = ( a 11 a 12 a 13 a 14 a 21
a 22 a 23 a 24 a 31 a 32 a 33 a 34 a 41 a 42 a 43 a 44 ) ( formula
.times. .times. 77 ) ##EQU00049.2##
[1050] where a.sub.11, a.sub.12, a.sub.13, a.sub.14, a.sub.21,
a.sub.22, a.sub.23, a.sub.24, a.sub.31, a.sub.32, a.sub.33,
a.sub.34, a.sub.41, a.sub.42, a.sub.43, and a.sub.44 are real
numbers. However, none of the following may hold: {a.sub.11=0,
a.sub.12=0, a.sub.13=0, and a.sub.14=0}, {a.sub.21=0, a.sub.22=0,
a.sub.23=0, and a.sub.24=0}, {a.sub.310, a.sub.32=0, a.sub.33=0,
and a.sub.34=0}, and {a.sub.41=0, a.sub.42=0, a.sub.43=0, and
a.sub.44=0}. Also, none of the following may hold: {a.sub.11=0,
a.sub.21=0, a.sub.31=0, and a.sub.41=0}, {a.sub.12=0, a.sub.22=0,
a.sub.32=0, and a.sub.42=0}, {a.sub.13=0, a.sub.23=0, a.sub.33=0,
and a.sub.43=0}, and {a.sub.14=0, a.sub.24=0, a.sub.34=0, and
a.sub.44=0}.
Embodiment E1
[1051] The present Embodiment describes a transmission scheme as an
application of the change in phase to precoded signals (or precoded
signals having switched basebands) for a broadcasting system using
the DVB-T2 (Digital Video Broadcasting for a second generation
digital terrestrial television broadcasting system) standard.
First, the configuration of a frame in a broadcasting system using
the DVB-T2 standard is described.
[1052] FIG. 74 illustrates the overall frame configuration of a
signal transmitted by a broadcaster using the DVB-T2 standard.
Given that DVB-T2 uses an OFDM method, the frame is configured in
the time-frequency domain. Thus, FIG. 74 illustrates frame
configuration in the time-frequency domain. The frame includes P1
signaling data (7401), L1 pre-signaling data (7402), L1
post-signaling data (7403), a common PLP (Physical Layer Pipe)
(7404), and PLPs #1 through #N (7405_1 through 7405_N). (Here, L1
pre-signaling data (7402) and L1 post-signaling data (7403) are
termed P2 symbols.) As such, the P1 signaling data (7401), L1
pre-signaling data (7402), L1 post-signaling data (7403), a common
PLP (Physical Layer Pipe) (7404), and PLPs #1 through #N (7405_1
through 7405_N) form a frame, which is termed a T2 frame, thus
constituting a frame configuration unit.
[1053] The P1 signaling data (7401) is a symbol used by the
reception device for signal detection and frequency synchronization
(including frequency offset estimation), that simultaneously serves
to transmit information such as the FFT size and whether the
modulated signal is transmitted by a SISO or MISO method. (With
SISO methods, only one modulated signal is transmitted, while with
MISO methods, a plurality of modulated signals are transmitted. In
addition, the space-time blocks described in Non-Patent Literature
9, 16, and 17 may be used.)
[1054] The L1 pre-signaling data (7402) is used to transmit
information regarding the methods used to transmit the frame,
concerning the guard interval, the signal processing method
information used to reduce the PAPR (Peak-to-Average Power Ratio),
the modulation method used to transmit the L1 post-signaling data,
the FEC method, the encoding rate thereof, the length and size of
the L1 post-signaling data, them the payload pattern, the
cell(frequency region)-specific numbers, and whether normal mode or
extended mode is in use (where normal mode and extended mode differ
in terms of sub-carrier numbers used to transmit data).
[1055] The L1 post-signaling data (7403) is used to transmit such
information as the number of PLPs, the frequency region in use, the
PLP-specific numbers, the modulation method used to transmit the
PLPs, the FEC method, the encoding rate thereof, the number of
blocks transmitted by each PLP, and so on.
[1056] The common PLP (7404) and the PLPs #1 through #N (7405_1
through 7405_N) are areas used for data transmission.
[1057] The frame configuration from FIG. 74 illustrates the P1
signaling data (7401), L1 pre-signaling data (7402), L1
post-signaling data (7403), the common PLP (Physical Layer Pipe)
(7404), and the PLPs #1 through #N (7405_1 through 7405_N) divided
with respect to the time domain for transmission. However, two or
more of these signals may occur simultaneously. FIG. 75 illustrates
such a case. As shown, the L1 pre-signaling data, L1 post-signaling
data, and common PLP occur at the same timestamp, while PLP#1 and
PLP#2 occur simultaneously at another timestamp. That is, each
signal may coexist at the same point with respect to the time or
frequency domain within the frame configuration.
[1058] FIG. 76 illustrates a sample configuration of a transmission
device (e.g., a broadcaster) applying a transmission method in
which a change in phase is performed on precoded (or precoded and
switched) signals conforming to the DVB-T2 standard.
[1059] A PLP signal generator 7602 takes PLP transmit data 7601
(data for the PLPs) and a control signal 7609 as input, performs
error-correcting coding according to the error-correcting code
information for the PLPs included in the control signal 7609 and
performs mapping according to the modulation method similarly
included in the control signal 7609, and then outputs a PLP
(quadrature) baseband signal 7603.
[1060] A P2 symbol signal generator 7605 takes P2 symbol transmit
data 7604 and the control signal 7609 as input, performs
error-correcting coding according to the error-correcting code
information for the P2 symbol included in the control signal 7609
and performs mapping according to the modulation method similarly
included in the control signal 7609, and then outputs a P2 symbol
(quadrature) baseband signal 7606.
[1061] A control signal generator 7608 takes P1 symbol transmit
data 7607 and the P2 symbol transmit data 7604 as input and outputs
the control signal 7609 for the group of symbols from FIG. 74 (the
P1 signaling data (7401), the L1 pre-signaling data (7402), the L1
post-signaling data (7403), the common PLP (7404), and PLPs #1
through #N (7405_1 through 7405_N)). The control signal 7609 is
made up of transmission method information (such as the
error-correcting codes and encoding rate therefor, the modulation
method, the block length, the frame configuration, the selected
transmission method in which the precoding matrix is regularly
changed, the pilot symbol insertion method, IFFT/FFT information,
the PAPR reduction method, and the guard interval insertion method)
for the symbol group.
[1062] A frame configurator 7610 takes a PLP baseband signal 7603,
the P2 symbol baseband signal 7606, and the control signal 7609 as
input, performs reordering with respect to the time and frequency
domains according to the frame configuration information included
in the control signal, and accordingly outputs (quadrature)
baseband signal 7611_1 for stream 1 (a mapped signal, i.e., a
baseband signal on which the modulation method has been used) and
(quadrature) baseband signal 7611_2 for stream 2 (also a mapped
signal, i.e., a baseband signal on which the modulation method has
been used).
[1063] A signal processor 7612 takes the baseband signal for stream
1 7611_1, the baseband signal for stream 2 7611_2, and the control
signal 7609 as input, and then outputs modulated signals 1 (7613_1)
and 2 (7613_2), processed according to the transmission method
included in the control signal 7609.
[1064] Here, the characteristic feature is that when the
transmission method for performing the change of phase on precoded
(or precoded and switched) signals is selected, the signal
processor performs the change in phase on the precoded (or precoded
and switched) signals as indicated in FIGS. 6, 25 through 29, and
69. The signals so processed are output as processed modulated
signal 1 (7613_1) and processed modulated signal 2 (7613_2).
[1065] A pilot inserter 7614_1 takes processed modulated signal 1
(7613_1) and control signal 7609 as input, inserts pilot symbols
into processed modulated signal 1 (7613_1) according to the pilot
symbol insertion method information included in the control signal
7609, and outputs a post-pilot symbol insertion modulated signal
7615_1.
[1066] Another pilot inserter 7614_2 takes processed modulated
signal 2 (7613_2) and control signal 7609 as input, inserts pilot
symbols into processed modulated signal 2 (7613_2) according to the
pilot symbol insertion method information included in the control
signal 7609, and outputs a post-pilot symbol insertion modulated
signal 7615_2.
[1067] An IFFT unit 7616_1 takes post-pilot symbol insertion
modulated signal 7615_1 and the control signal 7609 as input,
applies an IFFT according to the IFFT method information included
in the control signal 7609, and outputs post-IFFT signal
7617_1.
[1068] Another IFFT unit 7616_2 takes post-pilot symbol insertion
modulated signal 7615_2 and the control signal 7609 as input,
applies an IFFT according to the IFFT method information included
in the control signal 7609, and outputs post-IFFT signal
7617_2.
[1069] PAPR reducer 7618_1 takes post-IFFT signal 7617_1 and
control signal 7609 as input, applies PAPR-reducing processing to
post-IFFT signal 7617_1 according to the PAPR reduction information
included in the control signal 7609, and outputs post-PAPR
reduction signal 7619_1.
[1070] PAPR reducer 7618_2 takes post-IFFT signal 7617_2 and
control signal 7609 as input, applies PAPR-reducing processing to
post-IFFT signal 7617_2 according to the PAPR reduction information
included in the control signal 7609, and outputs post-PAPR
reduction signal 7619_2.
[1071] Guard interval inserter 7620_1 takes post-PAPR reduction
signal 7619_1 and the control signal 7609 as input, inserts guard
intervals into post-PAPR reduction 7619_1 according to the guard
interval insertion method information included in the control
signal 7609, and outputs post-guard interval insertion signal
7621_1.
[1072] Guard interval inserter 7620_2 takes post-PAPR reduction
signal 7619_2 and the control signal 7609 as input, inserts guard
intervals into post-PAPR reduction 7619_2 according to the guard
interval insertion method information included in the control
signal 7609, and outputs post-guard interval insertion signal
7621_2.
[1073] A P1 symbol inserter 7622 takes the P1 symbol transmit data
7607 and the post-guard interval insertion signals 7621_1 and
7621_2 as input, generates P1 symbol signals from the P1 symbol
transmit data 7607, adds the P1 symbols to the respective
post-guard interval insertion signals 7621_1 and 7621_2, and
outputs post-P1 symbol addition signals 7623_1 and 7623_2. The P1
symbol signals may be added to one or both of post-guard interval
insertion signals 7621_1 and 7621_2. In the former case, the signal
to which nothing is added has zero signals as the baseband signal
in the interval to which the symbols are added to the other
signal.
[1074] Wireless processor 7624_1 takes post-P1 symbol addition
signal 7623_1 as input, performs processing such as frequency
conversion and amplification thereon, and outputs transmit signal
7625_1. Transmit signal 7625_1 is then output as radio waves by
antenna 7626_1.
[1075] Wireless processor 7624_2 takes post-P1 symbol addition
signal 7623_2 as input, performs processing such as frequency
conversion and amplification thereon, and outputs transmit signal
7625_2. Transmit signal 7625 _2 is then output as radio waves by
antenna 7626_2.
[1076] FIG. 77 illustrates a sample frame configuration in the
time-frequency domain where a plurality of PLPs are transmitted
after the P1 symbol, P2 symbol, and Common PLP have been
transmitted. As shown, with respect to the frequency domain, stream
1 (a mapped signal, i.e., a baseband signal on which the modulation
method has been used) uses sub-carriers #1 through #M, as does
stream 2 (also a mapped signal, i.e., a baseband signal on which
the modulation method has been used). Accordingly, when both s1 and
s2 have a symbol on the same sub-carrier at the same timestamp, a
symbol from each of the two stream is present at a single
frequency. As explained in other Embodiments, when using a
transmission method that involves performing a change of phase on
precoded (or precoded and switched) signals, the change in phase
may be performed in addition to weighting using the precoding
matrix (and, where applicable, after switching the baseband
signal). Accordingly, signals z1 and z2 are obtained. The signals
z1 and z2 are each output by a different antenna.
[1077] As shown in FIG. 77, interval 1 is used to transmit symbol
group 7701 of PLP#1 using stream s1 and stream s2. Data are
transmitted using a spatial multiplexing MIMO system as illustrated
by FIG. 23, or by using a MIMO system with a fixed precoding matrix
(where no change in phase performed).
[1078] Interval 2 is used to transmit symbol group 7702 of PLP#2
using stream s1. Data are transmitted using one modulated
signal.
[1079] Interval 3 is used to transmit symbol group 7703 of PLP#3
using stream s1 and stream s2. Data are transmitted using a
transmission method in which a change in phase is performed on
precoded (or precoded and switched) signals.
[1080] Interval 4 is used to transmit symbol group 7704 using
stream s1 and stream s2. Data are transmitted using the time-space
block codes described in Non-Patent Literature 9, 16, and 17.
[1081] When a broadcaster transmits PLPs as illustrated by FIG. 77,
the reception device from FIG. 77 receiving the transmit signals
must know the transmission method of each PLP. Accordingly, as
described above, the L1 post-signaling data (7403 from FIG. 74),
being the P2 symbol, should transmit the transmission scheme for
each PLP. The following describes an example of a configuration
method for P1 and P2 symbols in such circumstances.
[1082] Table 2 lists specific examples of control information
carried by the P1 symbol.
TABLE-US-00002 TABLE 2 S1 (3-bit) Control Information 000 T2_SISO
(transmission of one modulated signal in the DVB-T2 standard) 001
T2_MISO (transmission using time-space block codes in the DVB-T2
standard) 010 NOT_T2 (using a standard other than DVB-T2)
[1083] In the DVB-T2 standard, S1 control information (three bits
of data) is used by the reception device to determine whether or
not DVB-T2 is being used, and in the affirmative case, to determine
the transmission method.
[1084] As indicated in Table 2, above, the 3-bit S1 data are set to
000 to indicate that the modulated signals being transmitted
conform to transmission of one modulated signal in the DVB-T2
standard.
[1085] Alternatively, the 3-bit S1 data are set to 001 to indicate
that the modulated signals being transmitted conform to the use of
time-space block codes in the DVB-T2 standard.
[1086] In DVB-T2, 010 through 111 are reserved for future use. In
order to apply the present invention while maintaining
compatibility with DVB-T2, the 3-bit S1 data should be set to 010,
for example (anything other than 000 and 001 may be used.), and
should indicate that a standard other than DVB-T2 is being used for
the modulated signals. Thus, the reception device or terminal is
able to determine that the broadcaster is transmitting using
modulated signals conforming to a standard other than DVB-T2 by
detecting that the data read 010.
[1087] The following describes an example of a configuration method
for a P2 symbol used when the modulated signals transmitted by the
broadcaster conform to a standard other than DVB-T2. In the first
example, a scheme of using the P2 symbol within the DVB-T2
standard.
[1088] Table 3 lists a first example of control information
transmitted by the L1 post-signaling data in the P2 symbol.
TABLE-US-00003 TABLE 3 PLP_MODE (2-bits) Control Information 00
SISO/SIMO 01 MISO/MIMO (space-time block codes) 10 MIMO (performing
a change of phase on precoded signals (or precoded signals having
switched basebands)) 11 MIMO (using a fixed precoding matrix, or
using spatial multiplexing)
[1089] The above-given tables use the following abbreviations.
[1090] SISO: Single-Input Single-Output (one modulated signal
transmitted and received by one antenna) [1091] SIMO: Single-Input
Multiple-Output (one modulated signal transmitted and received by
multiple antennas) [1092] MISO: Multiple-Input Single-Output
(multiple modulated signals transmitted by multiple antennas and
received by a single antenna) [1093] MIMO: Multiple-Input
Multiple-Output (multiple modulated signals transmitted and
received by multiple antennas)
[1094] The two-bit data listed in Table 3 are the PLP_MODE
information. As shown in FIG. 77, this information is control
information for informing the terminal of the transmission method
(symbol group of PLP#1 through #4 in FIG. 77; hereinafter, symbol
group). The PLP_MODE information is present in each PLP. That is,
in FIG. 77, the PLP_MODE information for PLP#1, for PLP#2, for
PLP#3, for PLP#4, and so on, is transmitted by the broadcaster.
Naturally, the terminal acknowledges the transmission method used
by the broadcaster for the PLPs by demodulating (or by performing
error-correcting decoding on) this information.
[1095] When the PLP_MODE is set to 00, data are transmitted by that
PLP using a method in which a single modulated signal is
transmitted. When the PLP_MODE is set to 01, data are transmitted
by that PLP using a method in which multiple modulated signals are
transmitted using space-time block codes. When the PLP_MODE is set
to 10, data are transmitted by that PLP using a method in which a
change in phase is performed on precoded (or precoded and switched)
signals. When the PLP_MODE is set to 11, data are transmitted by
that PLP using a method in which a fixed precoding matrix is used,
or in which a spatial multiplexing MIMO system, is used.
[1096] When the PLP_MODE is set to any of 01 through 11, the
broadcaster must transmit the specific processing (e.g., the
specific transmission method by which the change in phase is
applied to precoded (or precoded and switched) signals, the
encoding method of time-space block codes, or the configuration of
the precoding matrix) to the terminal. The following describes an
alternative to Table 3, as a configuration method for control
information that includes the control information necessitated by
such circumstances.
[1097] Table 4 lists a second example of control information
transmitted by the L1 post-signaling data in the P2 symbol,
different from that of Table 3.
TABLE-US-00004 TABLE 4 No. of Name bits Control Information
PLP_MODE (1-bit) 0 SISO/SIMO 1 MISO/MIMO, using one of (i)
space-time block codes; (ii) change in phase performed on precoded
signals (or precoded signals having switched basebands); (iii) a
fixed precoding matrix; and (iv) spatial multiplexing MIMO_MODE 0
change in phase on precoded signals (or (1-bit) precoded signals
having switched basebands) is OFF 1 change in phase on precoded
signals (or precoded signals having switched basebands) is ON
MIMO_PATTERN#1 00 space-time block codes (2-bit) 01 fixed precoding
matrix #1 10 fixed precoding matrix #2 11 spatial multiplexing
MIMO_PATTERN#2 00 change in phase on precoded signals (or (2-bit)
precoded signals having switched basebands), version #1 01 change
in phase on precoded signals (or precoded signals having switched
basebands), version #2 10 change in phase on precoded signals (or
precoded signals having switched basebands), version #3 11 change
in phase on precoded signals (or precoded signals having switched
basebands), version #4
[1098] As indicated in Table 4, four types of control information
are possible: 1-bit PLP_MODE information, 1-bit MIMO_MODE
information, 2-bit MIMO_PATTERN#1 information, and 2-bit
MIMO_PATTERN#2 information. As shown in FIG. 77, the terminal is
notified of the transmission method for each PLP (namely PLP#1
through #4) by this information. The four types of control
information are present in each PLP. That is, in FIG. 77, the
PLP_MODE information, MIMO_MODE information, MIMO_PATTERN#1
information, and MIMO_PATTERN#2 information for PLP#1, for PLP#2,
for PLP#3, for PLP#4, and so on, is transmitted by the broadcaster.
Naturally, the terminal acknowledges the transmission method used
by the broadcaster for the PLPs by demodulating (or by performing
error-correcting decoding on) this information.
[1099] When the PLP_MODE is set to 0, data are transmitted by that
PLP using a method in which a single modulated signal is
transmitted. When the PLP_MODE is set to 1, data are transmitted by
that PLP using a method in which any one of the following applies:
(i) space-time block codes are used; (ii) a MIMO system is used
where a change in phase is performed on precoded (or precoded and
switched) signals; (iii) a MIMO system is used where a fixed
precoding matrix is used; and (iv) spatial multiplexing is
used.
[1100] When the PLP_MODE is set to 1, the MIMO_MODE information is
valid. When the MIMO_MODE information is set to 0, data are
transmitted without using a change in phase performed on precoded
(or precoded and switched) signals. When the MIMO_MODE information
is set to 1, data are transmitted using a change in phase performed
on precoded (or precoded signals having switched basebands).
[1101] When the PLP_MODE is set to 1 and the MIMO_MODE information
is set to 0, the MIMO_PATTERN#1 information is valid. When the
MIMO_PATTERN#1 information is set to 00, data are transmitted using
space-time block codes. When the MIMO_PATTERN#1 information is set
to 01, data are transmitted using fixed precoding matrix #1 for
weighting. When the MIMO_PATTERN#1 information is set to 10, data
are transmitted using fixed precoding matrix #2 for weighting.
(Precoding matrix #1 and precoding matrix #2 are different
matrices.) When the MIMO_PATTERN#1 information is set to 11, data
are transmitted using spatial multiplexing MIMO.
[1102] When the PLP_MODE is set to 1 and the MIMO_MODE information
is set to 1, the MIMO_PATTERN#2 information is valid. When the
MIMO_PATTERN#2 information is set to 00, data are transmitted using
version #1 of a change in phase on precoded (or precoded signals
having switched basebands). When the MIMO_PATTERN#2 information is
set to 01, data are transmitted using version #2 of a change in
phase on precoded (or precoded signals having switched basebands).
When the MIMO_PATTERN#2 information is set to 10, data are
transmitted using version #3 of a change in phase on precoded (or
precoded signals having switched basebands). When the
MIMO_PATTERN#2 information is set to 11, data are transmitted using
version #4 of a change in phase on precoded (or precoded signals
having switched basebands). Although the change in phase is
performed in four different versions #1 through 4, the following
three approaches are possible, given two different methods #A and
#B: [1103] Phase changes performed using method #A and performed
using method #B include identical and different changes. [1104] A
phase changing value included in method #A is not included in
method #B; and Multiple phase changes used in method #A are not
included in method #B.
[1105] The control information listed in Table 3 and Table 4,
above, is transmitted by the L1 post-signaling data in the P2
symbol. However, in the DVB-T2 standard, the amount of information
transmittable as a P2 symbol is limited. Accordingly, the
information listed in Tables 3 and 4 must be added to the
information that must be transmitted by the P2 symbol in the DVB-T2
standard. When this leads to exceeding the limit on information
transmittable as the P2 symbol, then as shown in FIG. 78, a
signaling PLP (7801) may be prepared in order to transmit necessary
control information (at least partially, i.e., transmitting the L1
post-signaling data and the signaling PLP) not included in the
DVB-T2 specification. While FIG. 78 illustrates a frame
configuration identical to that of FIG. 74, no limitation is
intended in this regard. A specific time and specific carrier
region may also be allocated in the time-frequency domain for the
signaling PLP, as in FIG. 75. That is, the signaling PLP may be
freely allocated in the time-frequency domain.
[1106] As described above, selecting a transmission method that
uses a multi-carrier method such as OFDM and preserves
compatibility with the DVB-T2 standard, and in which the change in
phase is performed on precoded (or precoded and switched) signals
has the merits of leading to better reception quality in the LOS
environment and to greater transmission speeds. While the present
invention describes the possible transmission methods for the
carriers as being spatial multiplexing MIMO, MIMO using a fixed
precoding matrix, a transmission method performing a change of
phase on precoded (or on precoded and switched) signals, space-time
block codes, and transmission methods transmitting only stream s1,
no limitation is intended in this manner.
[1107] Also, although the description indicates that the
broadcaster selects one of the aforementioned transmission methods,
these are not the only transmission methods available for
selection. Other options include: [1108] MIMO using a fixed
precoding matrix, a transmission method performing a change of
phase on precoded (or on precoded and switched) signals, space-time
block codes, and transmission methods transmitting only stream s1;
[1109] MIMO using a fixed precoding matrix, a transmission method
performing a change of phase on precoded (or on precoded and
switched) signals, and space-time block codes; [1110] MIMO using a
fixed precoding matrix, a transmission method performing a change
of phase on precoded (or on precoded and switched) signals, and
transmission methods transmitting only stream s1; [1111] A
transmission method performing a change of phase on precoded (or on
precoded and switched) signals, space-time block codes, and
transmission methods transmitting only stream s1; [1112] MIMO using
a fixed precoding matrix and a transmission method performing a
change of phase on precoded (or on precoded and switched) signals;
[1113] A transmission method performing a change of phase on
precoded (or on precoded and switched) signals and space-time block
codes; [1114] A transmission method performing a change of phase on
precoded (or on precoded and switched) signals and transmission
methods transmitting only stream s1. [1115] As such, by including a
transmission method performing a change of phase on precoded (or on
precoded and switched) signals, the merits of leading to greater
data transmission speeds in the LOS environment and better
reception quality for the reception device are achieved.
[1116] Here, given that, as described above, S1 must be set for the
P1 symbol, another configuration method for the control information
(regarding the transmission method for each PLP), different from
that of Table 3, is possible. For example, Table 5, below.
TABLE-US-00005 TABLE 5 PLP_MODE (2-bit) Control Information 00
SISO/SIMO 01 MISO/MIMO (space-time block codes) 10 MIMO (change in
phase on precoded signals (or precoded signals having switched
basebands)) 11 Reserved
[1117] Table 5 differs from Table 3 in that setting the PLP_MODE
information to 11 is reserved. As such, when the transmission
method for the PLPs is as described in one of the above examples,
the number of bits forming the PLP_MODE information as in the
examples of Tables 3 and 5 may be made greater or smaller according
to the transmission methods available for selection.
[1118] Similarly, for Table 4, when, for example, a MIMO method is
used with a transmission method that does not support changing the
phase of precoded signals (or precoded signals having switched
basebands), the MIMO_MODE control information is not necessary.
Also, when, for example, MIMO schemes using a fixed precoding
matrix are not supported, then the MIMO_PATTERN#1 is not necessary.
Also, when multiple precoding matrices are not necessary, 1-bit
information may be used instead of 2-bit information. Furthermore,
two or more bits may be used when a plurality of precoding matrices
are available.
[1119] The same principles apply to the MIMO_PATTERN#2 information.
When the transmission method does not require a plurality of
methods of performing a change of phase on precoded (or precoded
and switched) signals, 1-bit information may be used instead of
2-bit information. Furthermore, two or more bits may be used when a
plurality of phase changing schemes are available.
[1120] Furthermore, although the present Embodiment describes a
transmission device having two antennas, no limitation is intended
in this regard. The control information may also be transmitted
using more than two antennas. In such circumstances, the number of
bits in each type of control information may be increased as
required in order to realize transmission using four antennas. The
above description control information transmission in the P1 and P2
symbol also applies to such cases.
[1121] While FIG. 77 illustrates the frame configuration for the
PLP symbol groups transmitted by the broadcaster as being divided
with respect to the time domain, the following variation is also
possible.
[1122] Unlike FIG. 77, FIG. 79 illustrates an example of a method
for arranging the symbols stream s1 and stream 2 in the
time-frequency domain, after the P1 symbol, the P2 symbol, and the
Common PLP have been transmitted. In FIG. 79, the symbols labeled
#1 are symbols of the symbol group of PLP#1 from FIG. 77.
Similarly, the symbols labeled #2 are symbols of the symbol group
of PLP#2, the symbols labeled #3 are symbols of the symbol group of
PLP#3, and the symbols labeled #4 are symbols of the symbol group
of PLP#4, all from FIG. 77. As in FIG. 77, PLP#1 is used to
transmit data using a spatial multiplexing MIMO system as
illustrated by FIG. 23, or by using a MIMO system with a fixed
precoding matrix. PLP#2 is used to transmit data using only one
modulated signal. PLP#3 is used to transmit data using a
transmission method in which a change in phase is performed on
precoded (or precoded and switched) signals. PLP#4 is used to
transmit data using space-time block codes.
[1123] In FIG. 79, when both s1 and s2 have a symbol on the same
sub-carrier (given as carrier in FIG. 79) at the same timestamp, a
symbol from each of the two stream is present at the common
frequency. As explained in other Embodiments, when using a
transmission method that involves performing a change of phase on
precoded (or precoded and switched) signals, the change in phase
may be performed in addition to weighting using the precoding
matrix (and, where applicable, after switching the baseband
signal). Accordingly, signals z1 and z2 are obtained. The signals
z1 and z2 are each output by a different antenna.
[1124] As described above, FIG. 79 differs from FIG. 77 in that the
PLPs are divided with respect to the time domain. In addition, FIG.
79 has a plurality of PLPs arranged with respect to the time and
frequency domains. That is, for example, the symbols of PLP#1 and
PLP#2 are at timestamp 1, while the symbols of PLP#3 and PLP#4 are
at timestamp 3. As such, PLP symbols having a different index (#X,
where X=1, 2, and so on) may be allocated to each symbol (made up
of a timestamp and a sub-carrier).
[1125] Although, for the sake of simplicity, FIG. 79 lists only #1
and #2 at timestamp 1, no limitation is intended in this regard.
Indices of PLP symbols other than #1 and #2 may be at timestamp #1.
Furthermore, the relationship between PLP indices and sub-carriers
at timestamp 1 is not limited to that illustrated by FIG. 79. The
indices of any PLP symbols may be assigned to any sub-carrier. The
same applies to other timestamps, in that the indices of any PLP
symbols may be assigned thereto.
[1126] Unlike FIG. 77, FIG. 80 illustrates an example of a method
for arranging the symbols stream s1 and stream 2 in the
time-frequency domain, after the P1 symbol, the P2 symbol, and the
Common PLP have been transmitted. The characteristic feature of
FIG. 80 is that, assuming that using a plurality of antennas for
transmission is the basis of the PLP transmission method, then
transmission using only stream 1 is not an option for the T2
frame.
[1127] Accordingly, in FIG. 80, PLP symbol group 8001 transmits
data using a spatial multiplexing MIMO system, or a MIMO system
using a fixed precoding matrix. Also, symbol group 8002 of PLP#2
transmits data using a transmission method performing a change of
phase on precoded (or on precoded and switched) signals. Further,
symbol group 8003 of PLP#3 transmits data using space-time block
code. PLP symbol groups following symbol group 8003 of PLP#3
transmit data using one of these methods, namely using a spatial
multiplexing MIMO system, or a MIMO system using a fixed precoding
matrix, using a transmission method performing a change of phase on
precoded (or on precoded and switched) signals, or using space-time
block codes.
[1128] Unlike FIG. 79, FIG. 81 illustrates an example of a method
for arranging the symbols stream s1 and stream 2 in the
time-frequency domain, after the P1 symbol, the P2 symbol, and the
Common PLP have been transmitted. In FIG. 81, the symbols labeled
#1 are symbols of the symbol group of PLP#1 from FIG. 80.
Similarly, the symbols labeled #2 are symbols of the symbol group
of PLP#2, the symbols labeled #3 are symbols of the symbol group of
PLP#3, and the symbols labeled #4 are symbols of the symbol group
of PLP#4, all from FIG. 80. As in FIG. 80, PLP#1 is used to
transmit data using a spatial multiplexing MIMO system as
illustrated by FIG. 23, or by using a MIMO system with a fixed
precoding matrix. PLP#2 is used to transmit data using a
transmission method in which a change of phase is performed on
precoded (or precoded and switched) signals. PLP#3 is used to
transmit data using space-time block codes.
[1129] In FIG. 81, when both s1 and s2 have a symbol on the same
sub-carrier (given as carrier in FIG. 81) at the same timestamp, a
symbol from each of the two streams is present at the common
frequency. As explained in other Embodiments, when using a
transmission method that involves performing a change of phase on
precoded (or precoded and switched) signals, the change in phase
may be performed in addition to weighting using the precoding
matrix (and, where applicable, after switching the baseband
signal). Accordingly, signals z1 and z2 are obtained. The signals
z1 and z2 are each output by a different antenna.
[1130] FIG. 81 differs from FIG. 80 in that the PLPs are divided
with respect to the time and frequency domains. That is, for
example, the symbols of PLP#1 and of PLP#2 are both at timestamp 1.
As such, PLP symbols having a different index (#X, where X=1, 2,
and so on) may be allocated to each symbol (made up of a timestamp
and a sub-carrier).
[1131] Although, for the sake of simplicity, FIG. 81 lists only #1
and #2 at timestamp 1, no limitation is intended in this regard.
Indices of PLP symbols other than #1 and #2 may be at timestamp #1.
Furthermore, the relationship between PLP indices and sub-carriers
at timestamp 1 is not limited to that illustrated by FIG. 81. The
indices of any PLP symbols may be assigned to any sub-carrier. The
same applies to other timestamps, in that the indices of any PLP
symbols may be assigned thereto. On the other hand, one timestamp
may also have symbols of only one PLP assigned thereto, as is the
case for timestamp 3. In other words, any assignment of PLP symbols
in the time-frequency domain is allowable.
[1132] Thus, given that the T2 frame includes no PLPs using
transmission methods transmitting only stream s1, the dynamic range
of the signals received by the terminal may be constrained, which
is likely to lead to improved received signal quality.
[1133] Although FIG. 81 is described using examples of selecting
one of transmitting data using a spatial multiplexing MIMO system,
or a MIMO system using a fixed precoding matrix, transmitting data
using a transmission method performing a change of phase on
precoded (or on precoded and switched) signals, and transmitting
data using space-time block codes, the selection of transmission
method is not limited as such. Other possibilities include: [1134]
selecting one of transmitting data using a transmission method
performing a change of phase on precoded (or on precoded and
switched) signals, transmitting data using space-time block codes,
and transmitting data using a MIMO system using a fixed precoding
matrix; [1135] selecting one of transmitting data using a
transmission method performing a change of phase on precoded (or on
precoded and switched) signals, and transmitting data using
space-time block codes; and [1136] selecting one of transmitting
data using a transmission method performing a change of phase on
precoded (or on precoded and switched) signals and transmitting
data using a MIMO system using a fixed precoding matrix.
[1137] While the above explanation is given for a T2 frame having
multiple PLPs, the following describes a T2 frame having only one
PLP.
[1138] FIG. 82 illustrates a sample frame configuration for stream
s1 and stream s2 in the time-frequency domain where the T2 frame
has only one PLP. Although FIG. 82 indicates control symbols, these
are equivalent to the above-described symbols, such as P1 and P2
symbols. In FIG. 82, interval 1 is used to transmit a first T2
frame, interval 2 is used to transmit a second T2 frame, interval 3
is used to transmit a third T2 frame, and interval 4 is used to
transmit a fourth T2 frame.
[1139] Furthermore, the first T2 frame in FIG. 82 transmits symbol
group 8101 of PLP#1-1. The selected transmission method is spatial
multiplexing MIMO or MIMO using a fixed precoding matrix.
[1140] The second T2 frame transmits symbol group 8102 of PLP#2-1.
The transmission method is transmission using a single modulated
signal.
[1141] The third T2 frame transmits symbol group 8103 of PLP#3-1.
The transmission method is transmission performing a change of
phase on precoded (or on precoded and switched) signals.
[1142] The fourth T2 frame transmits symbol group 8104 of PLP#4-1.
The transmission method is transmission using space-time block
codes.
[1143] In FIG. 82, when both s1 and s2 have a symbol on the same
sub-carrier at the same timestamp, a symbol from each of the two
streams is present at the common frequency. As explained in other
Embodiments, when using a transmission method that involves
performing a change of phase on precoded signals (or precoded
signals having switched basebands), the change in phase may be
performed in addition to weighting using the precoding matrix (and,
where applicable, after switching the baseband signal).
Accordingly, signals z1 and z2 are obtained. The signals z1 and z2
are each output by a different antenna.
[1144] As such, the transmission method may be set by taking the
data transmission speed and the data reception speed of the
terminal into consideration for each PLP. This has the dual merits
of allowing the data transmission speed to be enhanced and ensuring
high data reception quality. The configuration method for the
control information pertaining to the transmission method and so on
for the P1 and P2 symbols (and the signaling PLP, where applicable)
may be as given by Tables 2 through 5, thus obtaining the same
effects. FIG. 82 differs from FIG. 77 in that, while the frame
configuration from FIG. 77 and the like includes multiple PLPs in a
single T2 frame, thus necessitating control information pertaining
to the transmission method and so on of each PLP, the frame
configuration of FIG. 82 includes only one PLP per T2 frame. As
such, the only control information needed is for the transmission
information and so on pertaining the one PLP.
[1145] Although the above description discusses methods of
transmitting information pertaining to the transmission method of
PLPs using P1 and P2 symbols (and the signaling PLP, where
applicable), the following describes a method of transmitting
information pertaining to the transmission method of PLPs without
using the P2 symbol.
[1146] FIG. 83 illustrates a frame configuration in the
time-frequency domain applicable when a terminal receiving data
transmitted by a broadcaster is not compatible with the DVB-T2
standard. In FIG. 83, components operating in the manner described
for FIG. 74 use identical reference numbers. The frame of FIG. 83
includes P1 signaling data (7401), first signaling data (8301),
second signaling data (8302), a common PLP (7404), and PLPs #1
through #N (7405_1 through 7405_N). As such, the P1 signaling data
(7401), the first signaling data (8301), the second signaling data
(8302), the common PLP (7404), and the PLPs #1 through #N (7405_1
through 7405_N) form a frame, thus constituting a frame unit.
[1147] The P1 signaling data (7401) are a symbol used for signal
reception by the reception device and for frequency synchronization
(including frequency offset estimation). In addition, these data
transmit identification regarding whether or not the frame conforms
to the DVB-T2 standard, e.g., using the S1 data as indicated in
Table 2 for this purpose.
[1148] The first signaling data (8301) are used to transmit
information regarding the methods used to transmit the frame,
concerning the guard interval, the signal processing method
information used to reduce the PAPR, the modulation method used to
transmit the L1 post-signaling data, the FEC method, the encoding
rate thereof, the length and size of the L1 post-signaling data,
them the payload pattern, the cell(frequency region)-specific
numbers, and whether normal mode or extended mode is in use, and
other such information. Here, the first signaling data (8301) need
not necessarily be data conforming to the DVB-T2 standard.
[1149] The second signaling data (8302) is used to transmit such
information as the number of PLPs, the frequency region in use, the
PLP-specific numbers, the modulation method used to transmit the
PLPs, the FEC method, the encoding rate thereof, the number of
blocks transmitted by each PLP, and so on.
[1150] The frame configuration from FIG. 83 illustrates the first
signaling data (8301), the second signaling data (8302), the L1
post-signaling data (7403), the common PLP (7404), and the PLPs #1
through #N (7405_1 through 7405_N) divided with respect to the time
domain for transmission. However, two or more of these signals may
occur simultaneously. FIG. 84 illustrates such a case. As shown in
FIG. 84, the first signaling data, the second signaling data, and
the common PLP share a common timestamp, while PLP#1 and PLP#2
share a different common timestamp. That is, each signal may
coexist at the same point with respect to the time or frequency
domain within the frame configuration.
[1151] FIG. 85 illustrates a sample configuration of a transmission
device (e.g., a broadcaster) applying a transmission method in
which a change in phase is performed on precoded (or precoded and
switched) signals as explained thus far, but conforming to a
standard other than the DVB-T2 standard. In FIG. 85, components
operating in the manner described for FIG. 76 use identical
reference numbers and invoke the above descriptions.
[1152] A control signal generator 7608 takes first and second
signaling data 8501 and P1 symbol transmit data 7607 as input, and
outputs the control signal 7609 (made up of such information as the
error-correcting codes and encoding rate therefor, the modulation
method, the block length, the frame configuration, the selected
transmission method in which the precoding matrix is regularly
changed, the pilot symbol insertion method, IFFT/FFT information,
the PAPR reduction method, and the guard interval insertion method)
for the transmission method of each symbol group of FIG. 83.
[1153] A control symbol signal generator 8502 takes the first and
second signaling data transmit data 8501 and the control signal
7609 as input, performs error-correcting coding according to the
error-correcting code information for the first and second
signaling data included in the control signal 7609 and performs
mapping according to the modulation method similarly included in
the control signal 7609, and then outputs a first and second
signaling data (quadrature) baseband signal 8503.
[1154] In FIG. 85, the frame configurator 7610 takes the baseband
signal 8503 generated by the control symbol signal generator 8502
as input, rather than the baseband signal 7606 generated by the P2
symbol signal generator 7605 from FIG. 76.
[1155] The following describes, with reference to FIG. 77, a
transmission method for control information (information
transmitted by the P1 symbol and by the first and second signaling
data) and for the frame configuration of the transmit signal for a
broadcaster (base station) applying a transmission method in which
a change in phase is performed on precoded (or on precoded and
switched) signals in a system not conforming to the DVB-T2
standard.
[1156] FIG. 77 illustrates a sample frame configuration in the
time-frequency domain where a plurality of PLPs are transmitted
after the first and second signaling data and the Common PLP have
been transmitted. In FIG. 77, stream s1 uses sub-carrier #1 through
sub-carrier #M in the frequency domain. Similarly, stream s2 also
uses sub-carrier #1 through sub-carrier #M in the frequency domain.
Accordingly, when both s1 and s2 have a symbol on the same
sub-carrier at the same timestamp, a symbol from each of the two
streams is present at a single frequency. As explained in other
Embodiments, when using a transmission method that involves
performing a change of phase on precoded (or precoded and switched)
signals, the change in phase may be performed in addition to
weighting using the precoding matrix (and, where applicable, after
switching the baseband signal). Accordingly, signals z1 and z2 are
obtained. The signals z1 and z2 are each output by a different
antenna.
[1157] As shown in FIG. 77, interval 1 is used to transmit symbol
group 7701 of PLP#1 using stream s1 and stream s2. Data are
transmitted using a spatial multiplexing MIMO system as illustrated
by FIG. 23, or by using a MIMO system with a fixed precoding
matrix.
[1158] Interval 2 is used to transmit symbol group 7702 of PLP#2
using stream s1. Data are transmitted using one modulated
signal.
[1159] Interval 3 is used to transmit symbol group 7703 of PLP#3
using stream s1 and stream s2. Data are transmitted using a
transmission method in which a change in phase is performed on
precoded (or precoded and switched) signals.
[1160] Interval 4 is used to transmit symbol group 7704 of PLP#4
using stream s1 and stream s2. Data are transmitted using the
time-space block codes.
[1161] When a broadcaster transmits PLPs as illustrated by FIG. 77,
the reception device from FIG. 64 receiving the transmit signals
must know the transmission method of each PLP. Accordingly, as
described above, the first and second signaling data must be used
transmit the transmission method for each PLP. The following
describes an example of a configuration method for the P1 symbol
and for the first and second signaling data in such circumstances.
A specific example of control information carried by the P1 symbol
is given in Table 2.
[1162] In the DVB-T2 standard, S1 control information (three bits
of data) is used by the reception device to determine whether or
not DVB-T2 is being used, and in the affirmative case, to determine
the transmission method. The 3-bit S1 data are set to 000 to
indicate that the modulated signals being transmitted conform to
transmission of one modulated signal in the DVB-T2 standard.
[1163] Alternatively, the 3-bit S1 data are set to 001 to indicate
that the modulated signals being transmitted conform to the use of
time-space block codes in the DVB-T2 standard.
[1164] In DVB-T2, 010 through 111 are reserved for future use. In
order to apply the present invention while maintaining
compatibility with DVB-T2, the 3-bit S1 data should be set to 010,
for example (anything other than 000 and 001 may be used.), and
should indicate that a standard other than DVB-T2 is being used for
the modulated signals. Thus, the reception device or terminal is
able to determine that the broadcaster is transmitting using
modulated signals conforming to a standard other than DVB-T2 by
detecting that the data read 010.
[1165] The following describes a configuration method for the first
and second signaling data used when the modulated signals
transmitted by the broadcaster do not conform to the DVB-T2
standard. A second example of control information for the first and
second signaling data is given by Table 3.
[1166] The two-bit data listed in Table 3 are the PLP_MODE
information. As shown in FIG. 77, this information is control
information for informing the terminal of the transmission method
for each PLP (PLP#1 through #4 in FIG. 77). The PLP_MODE
information is present in each PLP. That is, in FIG. 77, the
PLP_MODE information for PLP#1, for PLP#2, for PLP#3, for PLP#4,
and so on, is transmitted by the broadcaster. Naturally, the
terminal acknowledges the transmission method used by the
broadcaster for the PLPs by demodulating (or by performing
error-correcting decoding on) this information.
[1167] When the PLP_MODE is set to 00, data are transmitted by that
PLP using a method in which a single modulated signal is
transmitted. When the PLP_MODE is set to 01, data are transmitted
by that PLP using a method in which multiple modulated signals are
transmitted using space-time block codes. When the PLP_MODE is set
to 10, data are transmitted by that PLP using a method in which a
change in phase is performed on precoded (or precoded and switched)
signals. When the PLP_MODE is set to 11, data are transmitted by
that PLP using a method in which a fixed precoding matrix is used,
or in which a spatial multiplexing MIMO system, is used.
[1168] When the PLP_MODE is set to any of 01 through 11, the
broadcaster must transmit the specific processing (e.g., the
specific transmission method by which a change in phase is applied
to precoded (or precoded and switched) signals, the encoding method
of time-space block codes, or the configuration of the precoding
matrix) to the terminal. The following describes an alternative to
Table 3, as a configuration method for control information that
includes the control information necessitated by such
circumstances.
[1169] A second example of control information for the first and
second signaling data is given by Table 4.
[1170] As indicated in Table 4, four types of control information
are possible: 1-bit PLP_MODE information, 1-bit MIMO_MODE
information, 2-bit MIMO_PATTERN#1 information, and 2-bit
MIMO_PATTERN#2 information. As shown in FIG. 77, the terminal is
notified of the transmission method for each PLP (namely PLP#1
through #4) by this information. The four types of control
information are present in each PLP. That is, in FIG. 77, the
PLP_MODE information, MIMO_MODE information, MIMO_PATTERN#1
information, and MIMO_PATTERN#2 information for PLP#1, for PLP#2,
for PLP#3, for PLP#4, and so on, is transmitted by the broadcaster.
Naturally, the terminal acknowledges the transmission method used
by the broadcaster for the PLPs by demodulating (or by performing
error-correcting decoding on) this information.
[1171] When the PLP_MODE is set to 0, data are transmitted by that
PLP using a method in which a single modulated signal is
transmitted. When the PLP_MODE is set to 1, data are transmitted by
that PLP using a method in which any one of the following applies:
(i) space-time block codes are used; (ii) a MIMO system is used
where a change in phase is performed on precoded (or precoded and
switched) signals; (iii) a MIMO system is used where a fixed
precoding matrix is used; and (iv) spatial multiplexing is
used.
[1172] When the PLP_MODE is set to 1, the MIMO_MODE information is
valid. When the MIMO_MODE information is set to 0, data are
transmitted without using a change in phase performed on recoded
signals (or precoded signals having switched basebands). When the
MIMO_MODE information is set to 1, data are transmitted using a
change in phase performed on recoded signals (or precoded signals
having switched basebands).
[1173] When the PLP_MODE information is set to 1 and the MIMO_MODE
information is set to 0, the MIMO_PATTERN#1 information is valid.
As such, when the MIMO_PATTERN#1 information is set to 00, data are
transmitted using space-time block codes. When the MIMO_PATTERN#1
information is set to 01, data are transmitted using fixed
precoding matrix #1 for weighting. When the MIMO_PATTERN#1
information is set to 10, data are transmitted using fixed
precoding matrix #2 for weighting. (Precoding matrix #1 and
precoding matrix #2 are different matrices.) When the
MIMO_PATTERN#1 information is set to 11, data are transmitted using
spatial multiplexing MIMO.
[1174] When the PLP_MODE information is set to 1 and the MIMO_MODE
information is set to 1, the MIMO_PATTERN#2 information is valid.
When the MIMO_PATTERN#2 information is set to 00, data are
transmitted using version #1 of a change in phase on precoded (or
precoded and switched) signals. When the MIMO_PATTERN#2 information
is set to 01, data are transmitted using version #2 of a change in
phase on precoded (or precoded signals having switched basebands).
When the MIMO_PATTERN#2 information is set to 10, data are
transmitted using version #3 of a change in phase on precoded (or
precoded signals having switched basebands). When the
MIMO_PATTERN#2 information is set to 11, data are transmitted using
version #4 of a change in phase on precoded (or precoded signals
having switched basebands). Although the change in phase is
performed in four different versions #1 through 4, the following
three approaches are possible, given two different methods #A and
#B: [1175] Phase changes performed using method #A and performed
using method #B include identical and different changes. [1176]
Some phase changing values are included in method #A but are not
included in method #B; and [1177] Multiple phase changes used in
method #A are not included in method #B.
[1178] The control information listed in Table 3 and Table 4,
above, is transmitted by the first and second signaling data. In
such circumstances, there is no particular need to use the PLPs to
transmit the control information.
[1179] As described above, selecting a transmission method that
uses a multi-carrier method such as OFDM while being identifiable
as differing from the DVB-T2 standard, and in which a change of
phase is performed on precoded (or precoded and switched) signals
has the merits of leading to better reception quality in the LOS
environment and to greater transmission speeds. While the present
invention describes the possible transmission methods for the
carriers as being spatial multiplexing MIMO, MIMO using a fixed
precoding matrix, a transmission method performing a change of
phase on precoded (or on precoded and switched) signals, space-time
block codes, and transmission methods transmitting only stream s1,
no limitation is intended in this manner.
[1180] Also, although the description indicates that the
broadcaster selects one of the aforementioned transmission methods,
these are not the only transmission methods available for
selection. Other options include: [1181] MIMO using a fixed
precoding matrix, a transmission method performing a change of
phase on precoded (or on precoded and switched) signals, space-time
block codes, and transmission methods transmitting only stream s1;
[1182] MIMO using a fixed precoding matrix, a transmission method
performing a change of phase on precoded (or on precoded and
switched) signals, and space-time block codes; [1183] MIMO using a
fixed precoding matrix, a transmission method performing a change
of phase on precoded (or on precoded and switched) signals, and
transmission methods transmitting only stream s1; [1184] A
transmission method performing a change of phase on precoded (or on
precoded and switched) signals, space-time block codes, and
transmission methods transmitting only stream s1; [1185] MIMO using
a fixed precoding matrix and a transmission method performing a
change of phase on precoded (or on precoded and switched) signals;
[1186] A transmission method performing a change of phase on
precoded (or on precoded and switched) signals and space-time block
codes; and [1187] A transmission method performing a change of
phase on precoded (or on precoded and switched) signals and
transmission methods transmitting only stream s1. [1188] As such,
by including a transmission method performing a change of phase on
precoded (or on precoded and switched) signals, the merits of
leading to greater data transmission speeds in the LOS environment
and better reception quality for the reception device are
achieved.
[1189] Here, given that, as described above, the S1 data must be
set for the P1 symbol, another configuration method for the control
information (regarding the transmission method for each PLP)
transmitted as the first and second signaling data, different from
that of Table 3, is possible. For example, see Table 5, above.
[1190] Table 5 differs from Table 3 in that setting the PLP_MODE
information to 11 is reserved. As such, when the transmission
method for the PLPs is as described in one of the above examples,
the number of bits forming the PLP_MODE information as in the
examples of Tables 3 and 5 may be made greater or smaller according
to the transmission methods available for selection.
[1191] Similarly, for Table 4, when, for example, a MIMO method is
used with a transmission method that does not support changing the
phase of precoded (or precoded and switched) signals, the MIMO_MODE
control information is not necessary. Also, when, for example, MIMO
schemes using a fixed precoding matrix are not supported, then the
MIMO_PATTERN#1 is not necessary. Also, when multiple precoding
matrices are not necessary, 1-bit information may be used instead
of 2-bit information. Furthermore, two or more bits may be used
when a plurality of precoding matrices are available.
[1192] The same principles apply to the MIMO_PATTERN#2 information.
When the transmission schemes does not require a plurality of
methods of performing a change of phase on precoded (or precoded
and switched) signals, 1-bit information may be used instead of
2-bit information. Furthermore, two or more bits may be used when a
plurality of phase changing schemes are available.
[1193] Furthermore, although the present Embodiment describes a
transmission device having two antennas, no limitation is intended
in this regard. The control information may also be transmitted
using more than two antennas. In such circumstances, the number of
bits in each type of control information may be increased as
required in order to realize transmission using four antennas. The
above description control information transmission in the P1 symbol
and in the first and second signaling data also applies to such
cases.
[1194] While FIG. 77 illustrates the frame configuration for the
PLP symbol groups transmitted by the broadcaster as being divided
with respect to the time domain, the following variation is also
possible.
[1195] Unlike FIG. 77, FIG. 79 illustrates an example of a method
for arranging the symbols stream s1 and stream 2 in the
time-frequency domain, after the P1 symbol, the first and second
signaling data, and the Common PLP have been transmitted.
[1196] In FIG. 79, the symbols labeled #1 are symbols of the symbol
group of PLP#1 from FIG. 77. Similarly, the symbols labeled #2 are
symbols of the symbol group of PLP#2, the symbols labeled #3 are
symbols of the symbol group of PLP#3, and the symbols labeled #4
are symbols of the symbol group of PLP#4, all from FIG. 77. As in
FIG. 77, PLP#1 is used to transmit data using a spatial
multiplexing MIMO system as illustrated by FIG. 23, or by using a
MIMO system with a fixed precoding matrix. PLP#2 is used to
transmit data using only one modulated signal. PLP#3 is used to
transmit data using a transmission method in which a change in
phase is performed on precoded (or precoded and switched) signals.
PLP#4 is used to transmit data using space-time block codes.
[1197] In FIG. 79, when both s1 and s2 have a symbol on the same
sub-carrier at the same timestamp, a symbol from each of the two
streams is present at the common frequency. As explained in other
Embodiments, when using a transmission method that involves
performing a change of phase on precoded (or precoded and switched)
signals, the change in phase may be performed in addition to
weighting using the precoding matrix (and, where applicable, after
switching the baseband signal). Accordingly, signals z1 and z2 are
obtained. The signals z1 and z2 are each output by a different
antenna.
[1198] As described above, FIG. 79 differs from FIG. 77 in that the
PLPs are divided with respect to the time domain. In addition, FIG.
79 has a plurality of PLPs arranged with respect to the time and
frequency domains. That is, for example, the symbols of PLP#1 and
PLP#2 are at timestamp 1, while the symbols of PLP#3 and PLP#4 are
at timestamp 3. As such, PLP symbols having a different index (#X,
where X=1, 2, and so on) may be allocated to each symbol (made up
of a timestamp and a sub-carrier).
[1199] Although, for the sake of simplicity, FIG. 79 lists only #1
and #2 at timestamp 1, no limitation is intended in this regard.
Indices of PLP symbols other than #1 and #2 may be at timestamp #1.
Furthermore, the relationship between PLP indices and sub-carriers
at timestamp 1 is not limited to that illustrated by FIG. 79. The
indices of any PLP symbols may be assigned to any sub-carrier. The
same applies to other timestamps, in that the indices of any PLP
symbols may be assigned thereto.
[1200] Unlike FIG. 77, FIG. 80 illustrates an example of a method
for arranging the symbols stream s1 and stream s2 in the
time-frequency domain, after the P1 symbol, the first and second
signaling data, and the Common PLP have been transmitted. The
characteristic feature of FIG. 80 is that, assuming that using a
plurality of antennas for transmission is the basis of the PLP
transmission method, then transmission using only stream 1 is not
an option for the T2 frame.
[1201] Accordingly, in FIG. 80, PLP symbol group 8001 transmits
data using a spatial multiplexing MIMO system, or a MIMO system
using a fixed precoding matrix. Also, symbol group 8002 of PLP#2
transmits data using a transmission method performing a change of
phase on precoded (or on precoded and switched) signals. Further,
symbol group 8003 of PLP#3 transmits data using space-time block
code. PLP symbol groups following symbol group 8003 of PLP#3
transmit data using one of these methods, namely using a spatial
multiplexing MIMO system, or a MIMO system using a fixed precoding
matrix, using a transmission method performing a change of phase on
precoded (or on precoded and switched) signals, or using space-time
block codes.
[1202] Unlike FIG. 79, FIG. 81 illustrates an example of a method
for arranging the symbols stream s1 and stream s2 in the
time-frequency domain, after the P1 symbol, the first and second
signaling data, and the Common PLP have been transmitted.
[1203] In FIG. 81, the symbols labeled #1 are symbols of the symbol
group of PLP#1 from FIG. 80. Similarly, the symbols labeled #2 are
symbols of the symbol group of PLP#2, the symbols labeled #3 are
symbols of the symbol group of PLP#3, and the symbols labeled #4
are symbols of the symbol group of PLP#4, all from FIG. 80. As in
FIG. 80, PLP#1 is used to transmit data using a spatial
multiplexing MIMO system as illustrated by FIG. 23, or by using a
MIMO system with a fixed precoding matrix. PLP#2 is used to
transmit data using a transmission method in which a change of
phase is performed on precoded (or precoded and switched) signals.
PLP#3 is used to transmit data using space-time block codes.
[1204] In FIG. 81, when both s1 and s2 have a symbol on the same
sub-carrier at the same timestamp, a symbol from each of the two
streams is present at the common frequency. As explained in other
Embodiments, when using a transmission method that involves
performing a change of phase on precoded (or precoded and switched)
signals, the change in phase may be performed in addition to
weighting using the precoding matrix (and, where applicable, after
switching the baseband signal). Accordingly, signals z1 and z2 are
obtained. The signals z1 and z2 are each output by a different
antenna.
[1205] As described above, FIG. 81 differs from FIG. 80 in that the
PLPs are divided with respect to the time domain. In addition, FIG.
81 has a plurality of PLPs arranged with respect to the time and
frequency domains. That is, for example, the symbols of PLP#1 and
of PLP#2 are both at timestamp 1. As such, PLP symbols having a
different index (#X, where X=1, 2, and so on) may be allocated to
each symbol (made up of a timestamp and a sub-carrier).
[1206] Although, for the sake of simplicity, FIG. 81 lists only #1
and #2 at timestamp 1, no limitation is intended in this regard.
Indices of PLP symbols other than #1 and #2 may be at timestamp #1.
Furthermore, the relationship between PLP indices and sub-carriers
at timestamp 1 is not limited to that illustrated by FIG. 81. The
indices of any PLP symbols may be assigned to any sub-carrier. The
same applies to other timestamps, in that the indices of any PLP
symbols may be assigned thereto. On the other hand, one timestamp
may also have symbols of only one PLP assigned thereto, as is the
case for timestamp 3. In other words, any assignment of PLP symbols
in the time-frequency domain is allowable.
[1207] Thus, given that the frame unit includes no PLPs using
transmission methods transmitting only stream s1, the dynamic range
of the signals received by the terminal may be constrained, which
is likely to lead to improved received signal quality
[1208] Although FIG. 81 is described using examples of selecting
one of transmitting data using a spatial multiplexing MIMO system,
or a MIMO system using a fixed precoding matrix, transmitting data
using a transmission method performing a change of phase on
precoded (or on precoded and switched) signals, and transmitting
data using space-time block codes, the selection of transmission
method is not limited as such. Other possibilities include: [1209]
selecting one of transmitting data using a transmission method
performing a change of phase on precoded (or on precoded and
switched) signals, transmitting data using space-time block codes,
and transmitting data using a MIMO system using a fixed precoding
matrix; [1210] selecting one of transmitting data using a
transmission method performing a change of phase on precoded (or on
precoded and switched) signals, and transmitting data using
space-time block codes; and [1211] selecting one of transmitting
data using a transmission method performing a change of phase on
precoded (or on precoded and switched) signals and transmitting
data using a MIMO system using a fixed precoding matrix.
[1212] While the above explanation is given for a frame unit having
multiple PLPs, the following describes a frame unit having only one
PLP.
[1213] FIG. 82 illustrates a sample frame configuration for stream
s1 and stream s2 in the time-frequency domain where the frame unit
has only one PLP.
[1214] Although FIG. 82 indicates control symbols, these are
equivalent to the above-described P1 symbol and to the first and
second signaling data. In FIG. 82, interval 1 is used to transmit a
first frame unit, interval 2 is used to transmit a second frame
unit, interval 3 is used to transmit a third frame unit, and
interval 4 is used to transmit a fourth frame unit.
[1215] Furthermore, the first frame unit in FIG. 82 transmits
symbol group 8101 of PLP#1-1. The transmission method is spatial
multiplexing MIMO or MIMO using a fixed precoding matrix.
[1216] The second frame unit transmits symbol group 8102 of
PLP#2-1. The transmission method is transmission using a single
modulated signal.
[1217] The third frame unit transmits symbol group 8103 of PLP#3-1.
The transmission method is a transmission method performing a
change of phase on precoded (or on precoded and switched)
signals.
[1218] The fourth frame unit transmits symbol group 8104 of
PLP#4-1. The transmission method is transmission using space-time
block codes.
[1219] In FIG. 82, when both s1 and s2 have a symbol on the same
sub-carrier at the same timestamp, a symbol from each of the two
streams is present at the common frequency. When using a
transmission method that involves performing a change of phase on
precoded (or precoded and switched) signals, the change in phase
may be performed in addition to weighting using the precoding
matrix (and, where applicable, after switching the baseband
signal). Accordingly, signals z1 and z2 are obtained. The signals
z1 and z2 are each output by a different antenna.
[1220] As such, the transmission method may be set by taking the
data transmission speed and the data reception speed of the
terminal into consideration for each PLP. This has the dual merits
of allowing the data transmission speed to be enhanced and ensuring
high data reception quality. The configuration method for the
control information pertaining to the transmission method and so on
for the P1 symbol and for the first and second signaling data may
be as given by Tables 2 through 5, thus obtaining the same effects.
The frame configuration of FIG. 82 differs from that of FIG. 77 and
the like, where each frame unit has multiple PLPs, and control
information pertaining to the transmission method for each of the
PLPs is required. In FIG. 82, each frame unit has only one PLP, and
thus, the only control information needed is for the transmission
information and so on pertaining to that single PLP.
[1221] The present Embodiment describes a method applicable to a
system using a DVB standard and in which the transmission method
involves performing a change of phase on precoded (or precoded and
switched) signals. The transmission method involving performing a
change of phase on precoded signals (or precoded signals having
switched basebands) is described in the present description.
Although the present Embodiment uses "control symbol" as a term of
art, this term has no influence on the present invention.
[1222] The following describes the space-time block codes discussed
in the present description and included in the present
Embodiment.
[1223] FIG. 94 illustrates the configuration of a modulated signal
using space-time block codes. As shown, a space-time block coder
(9402) takes a baseband signal based on a modulated signal as
input. For example, the space-time block coder (9402)takes symbol
s1, symbol s2, and so on as input. Then, as shown in FIG. 94,
space-time block coding is performed, resulting in z1 (9403A)
taking s1 as symbol #0, -s2* as symbol #1, s3 as symbol #2, -s4* as
symbol #3, and so on, and z2 (9403B) taking s2 as symbol #0, s1* as
symbol #1, s4 as symbol #2, s3* as symbol #3, and so on. Here,
symbol #X of z1 and symbol #X of z2 are simultaneous signals on a
common frequency, each broadcast from a different antenna. The
arrangement of symbols in the space-time block codes is not
restricted to the time domain. A group of symbols may also be
arranged in the frequency domain, or in the time-frequency domain,
as required. Furthermore, the space-time block coding method of
FIG. 94 is given as an example of space-time block codes. Other
space-time block codes may also be applied to each Embodiment
discussed in the present description.
Embodiment E2
[1224] The present Embodiment describes a reception method and a
reception device applicable to a communication system using the
DVB-T2 standard when the transmission method described in
Embodiment E1, which involves performing a change of phase on
precoded (or on precoded and switched) signals, is used.
[1225] FIG. 86 illustrates a sample configuration for a reception
device in a terminal, for use when the transmission device of the
broadcaster from FIG. 76 applies a transmission method involving a
change in phase of precoded (or precoded and switched) signals.
Components thereof operating identically to those of FIG. 7 use the
same reference numbers thereas.
[1226] In FIG. 86, a P1 symbol detector and decoder 8601 receives
the signal transmitted by the broadcaster and takes baseband
signals 704_X and 704_Y as input, thereby performing signal
detection and frequency synchronization. The P1 symbol detector and
decoder 8601 simultaneously obtains the control information
included in the P1 symbol (by performing demodulation and
error-correcting decoding thereon) and outputs the P1 symbol
control information 8602 so obtained.
[1227] OFDM-related processors 8600_X and 8600_Y take the P1 symbol
control information 8602 as input and modify the OFDM signal
processing method (such as the Fourier transform) accordingly.
(This is possible because, as described in Embodiment E1, the
signals transmitted by the broadcaster include transmission method
information in the P1 symbol.) The OFDM-related processors 8600_X
and 8600_Y then output the baseband signals 704_X and 704_Y after
performing demodulation thereon according to the signal processing
method.
[1228] A P2 symbol demodulator 8603 (which may also apply to the
signaling PLP) takes the baseband signals 704_X and 704_Y and the
P1 symbol control information 8602 as input, performs signal
processing and demodulation (including error-correcting decoding)
in accordance with the P1 symbol control information, and outputs
P2 symbol control information 8604.
[1229] A control information generator 8605 takes the P1 symbol
control information 8602 and the P2 symbol control information 8604
as input, bundles the control information (pertaining to reception
operations), and outputs a control signal 8606. Then, as shown in
FIG. 86, the control signal 8606 is input to each component.
[1230] A signal processor 711 takes signals 706_1, 706_2, 708_1,
708_2, 704_X, and 704_Y, as well as control signal 8606, as input,
performs demodulation an decoding according to the information
included in the control signal 8606, and outputs received data 712.
The information included in the control signal pertains to the
transmission method, modulation method, error-correcting coding
method and encoding rate thereof, error-correcting code block size,
and so on used for each PLP.
[1231] When the transmission method used for the PLPs is one of
spatial multiplexing MIMO, MIMO using a fixed precoding matrix, and
a transmission method performing a change of phase on precoded (or
on precoded and switched) signals, demodulation is performed by
obtaining received (baseband) signals using the output of the
channel estimators (705_1, 705_2, 707_1, and 707_2) and the
relationship of the received (baseband) signals to the transmit
signals. When the transmission method involves performing a change
of phase on precoded (or precoded and switched) signals,
demodulation is performed using the output of the channel
estimators (705_1, 705_2, 707_1, and 707_2), the received
(baseband) signals, and the relationship given by Math. 48 (formula
48).
[1232] FIG. 87 illustrates a sample configuration for a reception
device in a terminal, for use when the transmission device of the
broadcaster from FIG. 85 applies a transmission method involving a
change in phase of precoded (or precoded and switched) signals.
Components thereof operating identically to those of FIGS. 7 and 86
use the same reference numbers thereas.
[1233] The reception device from FIG. 87 differs from that of FIG.
86 in that, while the latter receives data from signals conforming
to the DVB-T2 standard and to other standards, the former receives
data only from signals conforming to a standard other than
DVB-T2.
[1234] In FIG. 87, a P1 symbol detector and decoder 8601 receives
the signal transmitted by the broadcaster and takes baseband
signals 704_X and 704_Y as input, thereby performing signal
detection and frequency synchronization. The P1 symbol detector and
decoder 8601 simultaneously obtains the control information
included in the P1 symbol (by performing demodulation and
error-correcting decoding thereon) and outputs the P1 symbol
control information 8602 so obtained.
[1235] OFDM-related processors 8600_X and 8600_Y take the P1 symbol
control information 8602 as input and modify the OFDM signal
processing method accordingly. (This is possible because, as
described in Embodiment E1, the signals transmitted by the
broadcaster include transmission method information in the P1
symbol.) The OFDM-related processors 8600_X and 8600_Y then output
the baseband signals 704_X and 704_Y after performing demodulation
thereon according to the signal processing method.
[1236] A first and second signaling data demodulator 8701 (which
may also apply to the signaling PLP) takes the baseband signals
704_X and 704_Y and the P1 symbol control information 8602 as
input, performs signal processing and demodulation (including
error-correcting decoding) in accordance with the P1 symbol control
information, and outputs first and second signaling data control
information 8702.
[1237] A control information generator 8605 takes the P1 symbol
control information 8602 and the first and second signaling data
control information 8702 as input, bundles the control information
(pertaining to reception operations), and outputs a control signal
8606. Then, as shown in FIG. 86, the control signal 8606 is input
to each component.
[1238] A signal processor 711 takes signals 706_1, 706_2, 708_1,
708_2, 704_X, and 704_Y, as well as control signal 8606, as input,
performs demodulation an decoding according to the information
included in the control signal 8606, and outputs received data 712.
The information included in the control signal pertains to the
transmission method, modulation method, error-correcting coding
method and encoding rate thereof, error-correcting code block size,
and so on used for each PLP.
[1239] When the transmission method used for the PLPs is one of
spatial multiplexing MIMO, MIMO using a fixed precoding matrix, and
a transmission method performing a change of phase on precoded (or
on precoded and switched) signals, demodulation is performed by
obtaining received (baseband) signals using the output of the
channel estimators (705_1, 705_2, 707_1, and 707_2) and the
relationship of the received (baseband) signals to the transmit
signals. When the transmission method involves performing a change
of phase on precoded (or precoded and switched) signals,
demodulation is performed using the output of the channel
estimators (705_1, 705_2, 707_1, and 707_2), the received
(baseband) signals, and the relationship given by Math. 48 (formula
48).
[1240] FIG. 88 illustrates the configuration of a reception device
for a terminal compatible with the DVB-T2 standard and with
standards other than DVB-T2. Components thereof operating
identically to those of FIGS. 7 and 86 use the same reference
numbers thereas.
[1241] FIG. 88 differs from FIGS. 86 and 87 in that the reception
device of the former is compatible with signals conforming to the
DVB-T2 standard as well as signals conforming to other standards.
As such, the reception device includes a P2 symbol or first and
second signaling data demodulator 8801, in order to enable
demodulation.
[1242] The P2 symbol or first and second signaling data demodulator
8801 takes the baseband signals 704_X and 704_Y, as well as the P1
symbol control information 8602, as input, uses the P1 symbol
control information to determine whether the received signals
conform to the DVB-T2 standard or to another standard (e.g., using
Table in such a determination), performs signal processing and
demodulation (including error-correcting decoding), and outputs
control information 8802, which includes information indicating the
standard to which the received signals conform. Otherwise, the
operations are identical to those explained for FIGS. 86 and
87.
[1243] A reception device configured as described in the above
Embodiment and receiving signals transmitted by a broadcaster
having the transmission device described in Embodiment E1 provides
higher received data quality by applying appropriate signal
processing. In particular, when receiving signals transmitted using
a transmission method that involves a change in phase applied to
precoded (or precoded and switched) signals, data transmission
effectiveness as well as signal quality are both improved in the
LOS environment.
[1244] Although the present Embodiment is described as a reception
device compatible with the transmission method described in
Embodiment E1, and therefore having two antennas, no limitation is
intended in this regard. The reception device may also have three
or more antennas. In such cases, the data reception quality may be
further improved by enhancing the diversity gain. Also, the
transmission device of the broadcaster may have three or more
transmit antennas and transmit three or more modulated signals. The
same effects are achievable by accordingly increasing the number of
antennas on the reception device of the terminal. Alternatively,
the reception device may have only one antenna and apply maximum
likelihood detection or approximate maximum likelihood detection.
In such circumstances, the transmission method is preferably one
that involves a change in phase of precoded (or precoded and
switched) signals.
[1245] The transmission method need not be limited to the specific
methods explained in the present description. As long as precoding
occurs and is preceded or followed by a change in phase, the same
results are obtainable for the present Embodiment.
Embodiment E3
[1246] The system of Embodiment E1, which applies, to the DVB-T2
standard, a transmission method involving a change in phase
performed on precoded (or precoded and switched) signals, includes
control information indicating the pilot insertion method in the L1
pre-signaling information. The present Embodiment describes a
method of applying a transmission method that involves a change in
phase performed on precoded signals (or precoded signals having
switched basebands) when the pilot insertion method in the L1
pre-signaling information is changed.
[1247] FIGS. 89A, 89B, 90A, and 90B illustrate sample frame
configurations conforming to the DVB-T2 standard in the
time-frequency domain in which a common frequency region is used in
a transmission method by which a plurality of modulated signals are
transmitted from a plurality of antennas. Here, the horizontal axes
represent frequency, i.e., the carrier numbers, while the vertical
axes represent time. FIGS. 89A and 90A illustrate frame
configurations for modulated signal z1 while FIGS. 89B and 90B
illustrate frame configurations for modulated signal z2, both of
which are as explained in the above Embodiments. The carrier
numbers are labeled f0, f1, f2, and so on, while time is labeled
t1, t2, t3 and so on. Also, symbols indicated at the same carrier
and time are simultaneous symbols at a common frequency.
[1248] FIGS. 89A, 89B, 90A, and 90B illustrate examples of pilot
symbol insertion positions conforming to the DVB-T2 standard. (In
DVB-T2, eight methods of pilot insertion are possible when a
plurality of antennas are used to transmit a plurality of modulated
signals. Two of these are presently illustrated.) Two types of
symbols are indicated, namely pilot symbols and data symbols. As
described for other Embodiments, when the transmission method
involves performing a change of phase on precoded signals (or
precoded signals having switched basebands), or involves precoding
using a fixed precoding matrix, then the data symbols of modulated
signal z1 are symbols of stream s1 and stream s2 that have
undergone weighting, as are the data symbols of modulated signal
z2. (However, a change in phase is also performed when the
transmission scheme involves doing so) When space-time block codes
or a spatial multiplexing MIMO system are used, the data symbols of
modulated signal z1 are the symbols of either stream s1 or of
stream s2, as are the symbols of modulated signal z2. In FIGS. 89A,
89B, 90A, and 90B, the pilot symbols are labeled with an index,
which is either PP1 or PP2. These represent pilot symbols using
different configuration methods. As described above, eight methods
of pilot insertion are possible in DVB-T2 (varying in terms of the
frequency at which pilot symbols are inserted in the frame), one of
which is indicated by the broadcaster. FIGS. 89A, 89B, 90A, and 90B
illustrate two pilot insertion methods among these eight. As
described in Embodiment E1, information pertaining to the pilot
insertion method selected by the broadcaster is transmitted to the
receiving terminal as the L1 pre-signaling data in the P2
symbol.
[1249] The following describes a method of applying a transmission
method involving a change in phase performed on precoded signals
(or precoded signals having switched basebands) complementing the
pilot insertion method. In this example, the transmission method
involves preparing ten different phase changing values, namely
F[0], F[1], F[2], F[3], F[4], F[5], F[6], F[7], F[8], and F[9].
FIGS. 91A and 91B illustrate the allocation of these phase changing
values in the time-frequency domain frame configuration of FIGS.
89A and 89B when a transmission method involving a change in phase
performed on precoded (or precoded and switched) signals is
applied. Similarly, FIGS. 92A and 92B illustrate the allocation of
these phase changing values in the time-frequency domain frame
configuration of FIGS. 90A and 90B when a transmission method
involving a change in phase performed on precoded (or precoded and
switched) signals is applied. For example, FIG. 91A illustrates the
frame configuration of modulated signal z1 while FIG. 91B
illustrates the frame configuration of modulated signal z2. In both
cases, symbol #1 at f1, t1 is a symbol on which frequency
modification has been performed using phase changing value F[1].
Accordingly, in FIGS. 91A, 91B, 92A, and 92B, a symbol at carrier
fx (where x=0, 1, 2, and so on), time ty (where y=1, 2, 3, and so
on) is labeled #Z to indicate that frequency modification has been
performed using phase changing value F[Z] on the symbol fx, ty.
[1250] Naturally, the insertion method (insertion interval) for the
frequency-time frame configuration of FIGS. 91A and 91B differs
from that of FIGS. 92A and 92B. The transmission method in which a
change of phase is performed on precoded signals (or precoded
signals having switched basebands) is not applied to the pilot
symbols. Therefore, although the same transmission method involving
a change in phase performed on the same synchronized precoded (or
precoded and switched) signals (for which a different number of
phase changing values may have been prepared), the phase changing
value assigned to a single symbol at a given carrier and time in
FIGS. 91A and 91B may be different in FIGS. 92A and 92B. This is
made clear by reference to the drawings. For example, the symbol at
f5, t2 in FIGS. 91A and 91B is labeled #7, indicating that a change
in phase has been performed thereon using phase changing value
F[7]. On the other hand, the symbol at f5, t2 in FIGS. 92A and 92B
is labeled #8, indicating that a change in phase has been performed
thereon using phase changing value F[8].
[1251] Accordingly, although the broadcaster transmits control
information indicating the pilot pattern (pilot insertion method)
in the L1 pre-signaling information, when the transmission method
selected by the broadcaster method involves a change in phase
performed on precoded signals (or precoded signals having switched
basebands), the control information may additionally indicate the
phase changing value allocation method used in the selected method
through the control information given by Table 3 or Table 4. Thus,
the reception device of the terminal receiving the modulated
signals transmitted by the broadcaster is able to determine the
phase changing value allocation method by obtaining the control
information indicating the pilot pattern in the L1 pre-signaling
data. (This presumes that the transmission method selected by the
broadcaster for PLP transmission from Table 3 or Table 4 is one
that involves a change in phase on precoded signals (or precoded
signals having switched basebands)). Although the above description
uses the example of L1 pre-signaling data, the above-described
control information may also be included in the first and second
signaling data when, as described for FIG. 83, no P2 symbols are
used.
[1252] The following describes further variant examples. Table 6
lists sample phase changing patterns and corresponding modulation
methods.
TABLE-US-00006 TABLE 6 No. of Modulated Signals Modulation Scheme
Phase Changing Pattern 2 #1: QPSK, #2: QPSK #1: --, #2: A 2 #1:
QPSK, #2: 16-QAM #1: --, #2: B 2 #1: 16-QAM, #2: 16-QAM #1: --, #2:
C . . . . . . . . .
[1253] For example, as shown in Table 6, when the modulation method
is indicated and the phase changing values to be used in the
transmission method involving a change in phase performed on
precoded signals (or precoded signals having switched basebands)
have been determined, the above-described principles apply. That
is, transmitting only the control information pertaining to the
pilot pattern, the PLP transmission method, and the modulation
method suffices to enable the reception device of the terminal to
estimate the phase changing value allocation method (in the
time-frequency domain) by obtaining this control information. In
Table 6, the Phase Changing Method column lists a dash to indicate
that no change in phase is performed, and lists #A, #B, or #C to
indicate phase changing methods #A, #B, and #C. Similarly, as shown
in Table 1, when the modulation method and the error-correcting
coding method are indicated and the phase changing values to be
used in the transmission method involving a change in phase of
precoded signals (or precoded signals having switched basebands)
have been determined, then transmitting only the control
information pertaining to the pilot pattern, the PLP transmission
method, the modulation method, and the error-correcting codes in
the P2 symbol suffices to enable the reception device of the
terminal to estimate the phase changing value allocation method (in
the time-frequency domain) by obtaining this control
information.
[1254] However, unlike Table 1 and Table 6, two or more different
types of transmission scheme involving a change in phase performed
on precoded signals (or precoded signals having switched basebands)
may be selected, despite the modulation scheme having been
determined (For example, the transmission schemes may have a
different period (cycle), or use different phase changing values).
Alternatively, two or more different types of transmission scheme
involving a change in phase performed on precoded signals (or
precoded signals having switched basebands) may be selected,
despite the modulation scheme and the error-correction scheme
having been determined. Furthermore, two or more different types of
transmission scheme involving a change in phase performed on
precoded signals (or precoded signals having switched basebands)
may be selected, despite the error-correction scheme having been
determined. In such cases, as shown in Table 4, the transmission
scheme involves switching between phase changing values. However,
information pertaining to the allocation scheme of the phase
changing values (in the time-frequency domain) may also be
transmitted.
[1255] Table 7 lists control information configuration examples for
information pertaining to such allocation methods.
TABLE-US-00007 TABLE 7 PHASE_FRAME_ARRANGEMENT (2-bit) Control
Information 00 allocation scheme #1 01 allocation scheme #2 10
allocation scheme #3 11 allocation scheme #4
[1256] For example, suppose that the transmission device of the
broadcaster selects FIGS. 89A and 89B as the pilot pattern
insertion method, and selects transmission method A, which involves
a change in phase on precoded signals (or precoded signals having
switched basebands). Thus, the transmission device may select FIGS.
91A and 91B or FIGS. 93A and 93B as the phase changing value
allocation method (in the time-frequency domain). For example, when
the transmission device selects FIGS. 91A and 91B, the
PHASE_FRAME_ARRANGEMENT information of Table 7 is set to 00. When
the transmission device selects FIGS. 93A and 93B, the
PHASE_FRAME_ARRANGEMENT information is set to 01. As such, the
reception device is able to determine the phase changing value
allocation method (in the time-frequency domain) by obtaining the
control information of Table 7. The control information of Table 7
is also applicable to transmission by the P2 symbol, and to
transmission by the first and second signaling data.
[1257] As described above, a phase changing value allocation method
for the transmission method involving a change in phase performed
on precoded (or precoded and switched) signals may be realized
through the pilot insertion method. In addition, by reliably
transmitting such allocation method information to the receiving
party, the reception device derives the dual benefits of improved
data transmission efficiency and enhanced received signal
quality.
[1258] Although the present Embodiment describes a broadcaster
using two transmit signals, the same applies to broadcasters using
a transmission device having three or more transmit antennas
transmitting three or more signals. The transmission method need
not be limited to the specific methods explained in the present
description. As long as precoding occurs and is preceded or
followed by a change in phase, the same results are obtainable for
the present Embodiment.
[1259] The pilot signal configuration method is not limited to the
present Embodiment. When the transmission method involves
performing a change of phase on precoded (or precoded and switched)
signals, the reception device need only implement the relationship
given by Math. 48 (formula 48) (e.g., the reception device may know
the pilot pattern signals transmitted by the transmission device in
advance). This applies to all Embodiments discussed in the present
description.
[1260] The transmission devices pertaining to the present
invention, as illustrated by FIGS. 3, 4, 12, 13, 51, 52, 67, 70,
76, 85, and so on transmit two modulated signals, namely modulated
signal #1 and modulated signal #2, on two different transmit
antennas. The average transmission power of the modulated signals
#1 and #2 may be set freely. For example, when the two modulated
signals each have a different average transmission power,
conventional transmission power control technology used in wireless
transmission systems may be applied thereto. Therefore, the average
transmission power of modulated signals #1 and #2 may differ. In
such circumstances, transmission power control may be applied to
the baseband signals (e.g., when mapping is performed using the
modulation method), or may be performed by a power amplifier
immediately before the antenna.
(Regarding Cyclic Q Delay)
[1261] The following describes the application of the Cyclic Q
Delay mentioned throughout the present disclosure. Non-Patent
Literature 10 describes the overall concept of Cyclic Q Delay. The
following describes a specific example of a generation method for
the s1 and s2 signals when Cyclic Q Delay is used.
[1262] FIG. 95 illustrates an example of a signal point arrangement
in the I-Q plane when the modulation method is 16-QAM. As shown,
when the input bits are b0, b1, b2, and b3, the bits take on either
a value of 0000 or a value of 1111. For example, when the bits b0,
b1, b2, and b3 are to be expressed as 0000, then signal point 9501
of FIG. 95 is selected, a value of the in-phase component based on
signal point 9501 is taken as the in-phase component of the
baseband signal, and a value of the quadrature component based on
signal point 9501 is taken as the quadrature component of the
baseband signal. When the bits b0, b1, b2, and b3 are to be
expressed as a different value, the in-phase component and the
quadrature component of the baseband signal are generated
similarly.
[1263] FIG. 96 illustrates a sample configuration of a signal
generator for generating modulated signals s1(t) (where t is time)
(alternatively, s1(f), where f is frequency) and s2(t)
(alternatively, s2(f)) from (binary) data when the cyclic Q delay
is applied.
[1264] A mapper 9602 takes data 9601 and a control signal 9606 as
input, and performs mapping in accordance with the modulation
method of the control signal 9606. For example, when 16-QAM is
selected as the modulation method, mapping is performed as
illustrated in FIG. 95. The mapper then outputs an in-phase
component 9603_A and a quadrature component 9603_B for the mapped
baseband signal. No limitation is intended to the modulation method
being 16-QAM, and the operations are similar for other modulation
methods.
[1265] Here, the data at time 1 corresponding to the bits b0, b1,
b2, and b3 from FIG. 95 are respectively indicated as b01, b11,
b21, and b31. The mapper 9602 outputs the in-phase component I1 and
the quadrature component Q1 for the baseband signal at time 1,
according to the data b0, b1, b2, and b3 at time 1. Similarly,
another mapper 9602 outputs the in-phase component 12 and the
quadrature component Q2 and so on for the baseband signal at time
2.
[1266] A memory and signal switcher 9604 takes the in-phase
component 9603_A and the quadrature component 9603_B of the
baseband signal as input and, in accordance with a control signal
9606, stores the in-phase component 9603_A and the quadrature
component 9603_B of the baseband signal, switches the signals, and
outputs modulated signal s1(t) (9605_A) and modulated signal s2(t)
(9605_B). The generation method for the modulated signals s1(t) and
s2(t) is described in detail below.
[1267] As described elsewhere in the disclosure, precoding and
phase changing are performed on the modulated signal s1(t) and
s2(t). Here, as described elsewhere, signal processing involving
phase change, power change, signal switching, and so on may be
applied at any step. Thus, modulated signals r1(t) and r2(t),
respectively obtained by applying the precoding and phase change to
the modulated signals s1(t) and s2(t), are transmitted using the
same (common) frequency band at the same (common) time.
[1268] Although the above description is given with respect to the
time domain, s1(t) and s2(t) may be thought of as s1(f) and s2(f)
(where f is the (sub-)carrier frequency) when a multi-carrier
transmission scheme such as OFDM is employed. In contrast to the
modulated signals s1(f) and s2(f), modulated signals r1(f) and
r2(f) obtained using a precoding scheme in which the precoding
matrix is regularly changed are transmitted at the same (common)
time (r1(f) and r2(f) being, of course) signals of the same
frequency band). Also, as described above, s1(t) and s2(t) may be
treated as s1(t,f) and s2(t,f).
[1269] The following describes the generation method for modulated
signals s1(t) and s2(t). FIGS. 97A, 97B, and 97C illustrate a first
example of a generation method for s1(t) and s2(t) when a cyclic Q
delay is used.
[1270] Portion (a) of FIG. 97 indicates the in-phase component and
the quadrature component of the baseband signal obtained by the
mapper 9602 of FIG. 96. As shown in FIG. 87A and as described with
reference to the mapper 9602 of FIG. 96, the mapper 9602 outputs
the in-phase component and the quadrature component of the baseband
signal such that in-phase component I1 and quadrature component Q1
occur at time 1, in-phase component 12 and quadrature component Q2
occur at time 2, in-phase component 13 and quadrature component Q3
occur at time 3, and so on.
[1271] Portion (b) of FIG. 97 illustrates a sample set of in-phase
components and quadrature components for the baseband signal when
signal switching is performed by the memory and signal switcher
9604 of FIG. 96. As shown, pairs of quadrature components are
switched at each of time 1 and time 2, time 3 and time 4, and time
5 and time 6 (i.e., time 2i+1 and time 2i+2, i being a non-zero
positive integer) such that, for example, the components at time 1
and t2 are switched.
[1272] Accordingly, given that signal switching is not performed on
the in-phase component of the baseband signal, the order thereof is
such that in-phase component I1 occurs at time 1, in-phase
component 12 occurs at time 2, baseband signal 13 occurs at time 3,
and so on.
[1273] Then, signal switching is performed within the pairs of
quadrature components for the baseband signal. Thus, quadrature
component Q2 occurs at time 1, quadrature component Q1 occurs at
time 2, quadrature component Q4 occurs at time 3, quadrature
component Q3 occurs at time 4, and so on.
[1274] Portion (c) of FIG. 97 indicates a sample configuration for
modulated signals s1(t) and s2(t) before precoding, when the scheme
applied involves precoding and phase changing. For example, as
shown in portion (c), the baseband signal generated in portion (b)
is alternately assigned to s1(t) and to s2(t). Thus, the first slot
of s1(t) takes (I1, Q2) and the first slot of s2(t) takes (I2, Q1).
Likewise, the second slot of s1(t) takes (I3, Q4) and the second
slot of s2(t) takes (I4, Q3). This continues similarly.
[1275] Although FIG. 97 describes an example with reference to the
time domain, the same applies to the frequency domain (exactly as
described above). In such cases, the descriptions pertain to s1(f)
and 2(f).
[1276] Then, N-slot precoded and phase changed modulated signals
r1(t) and r2(t) are obtained after applying the precoding and phase
change to the N-slot modulated signals s1(t) and s2(t). This point
is described elsewhere in the present disclosure.
[1277] FIG. 98 illustrates a configuration that differs from that
of FIG. 96 and is used to obtain the N-slot s1(t) and s2(t) from
FIGS. 97A through 97C. The mapper 9802 takes data and a control
signal 9804 as input and, in accordance with the modulation method
of the control signal 9804, for example, performs mapping in
consideration of the switching from FIG. 97, generates a mapped
signal (i.e., in-phase components and quadrature components of the
baseband signal) and generates modulated signal s1(t)(9803_A) and
modulated signal s2(t)(9803_B) from the mapped signal. Modulated
signal (s1(t) (9803_A) is identical to modulated signal 9605_A from
FIG. 96, and modulated signal s2(t) (9803_B) is identical to
modulated signal 9605_B from FIG. 6. This is as indicated in
portion (c) of FIG. 97. Accordingly, the first slot of modulated
signal s1(t) (9803_A) takes (I1, Q2), the first slot of modulated
signal s2(t) (9803_B) takes (I2, Q1), the second slot of modulated
signal s1(t) (9803_A) takes (I3, Q4), the second slot of modulated
signal s2(t) (9803_B) takes (I4, Q3), and so on.
[1278] The generation method for the first slot (I1, Q2) of
modulated signal s1(t) (9803_A) and the first slot (I2, Q1) of
modulated signal s2(t) (9803_B) by the mapper 9802 from FIG. 98 is
described below, as a supplement.
[1279] The data 9801 indicated in FIG. 98 is made up of time 1 data
b01, b11, b21, b31 and of time 2 data b02, b12, b22, b32. The
mapper 9802 of FIG. 98 generates I1, Q1, 12, and Q2 as described
above using the data b01, b11, b21, b31 and b02, b12, b22, and b32.
Thus, the mapper 9802 of FIG. 98 is able to generate the modulated
signals s1(t) and s2(t) from I1, Q1, I2, and Q2.
[1280] FIG. 99 illustrates a configuration that differs from those
of FIGS. 96 and 98 and is used to obtain the N-slot s1(t) and s2(t)
from FIGS. 97A through 97C. The mapper 9901_A takes data 9801 and a
control signal 9804 as input and, in accordance with the modulation
method of the control signal 9804, for example, performs mapping in
consideration of the switching from FIG. 97, generates a mapped
signal (i.e., in-phase components and quadrature components of the
baseband signal) and generates a modulated signal s1(t) (9803_A)
from the mapped signal. Similarly, the mapper 9901_B takes data
9801 and a control signal 9804 as input and, in accordance with the
modulation method of the control signal 9804, for example, performs
mapping in consideration of the switching from FIG. 97, generates a
mapped signal (i.e., in-phase components and quadrature components
of the baseband signal) and generates a modulated signal s2(t)
(9803_B) from the mapped signal.
[1281] The data 9801 input to the mapper 9901_A and the data 9801
input to the mapper 9901_B are, of course, identical data.
Modulated signal s1(t) (9803_A) is identical to modulated signal
9605_A from FIG. 96, and modulated signal s2(t) (9803_B) is
identical to modulated signal 9605_B from FIG. 6. This is as
indicated in portion (c) of FIG. 97.
[1282] Accordingly, the first slot of modulated signal s1(t)
(9803_A) takes (I1, Q2), the first slot of modulated signal s2(t)
(9803_B) takes (I2, Q1), the second slot of modulated signal s1(t)
(9803_A) takes (I3, Q4), the second slot of modulated signal s2(t)
(9803_B) takes (I4, Q3), and so on.
[1283] The generation method for the first slot (I1, Q2) of
modulated signal s1(t) (9803_A) by the mapper 9901_A from FIG. 99
is described below, as a supplement. The data 9901 indicated in
FIG. 99 are made up of time 1 data b01, b11, b21, b31 and of time 2
data b02, b12, b22, b32. The mapper 9901_A of FIG. 99 generates I1
and Q2 as described above using the data b01, b11, b21, b31 and
b02, b12, b22, and b32. The mapper 9901_A of FIG. 99 then generates
modulated signal s1(t) from I1 and Q2.
[1284] The generation method for the first slot (I2, Q1) of
modulated signal s2(t) (9803_B) by the mapper 9901_B from FIG. 99
is described below. The data 9801 indicated in FIG. 99 are made up
of time 1 data b01, b11, b21, b31 and of time 2 data b02, b12, b22,
b32. The mapper 9901_B of FIG. 99 generates 12 and Q1 as described
above using the data b01, b11, b21, b31 and b02, b12, b22, and b32.
Thus, the mapper 9901_B of FIG. 99 is able to generate modulated
signal s2(t) from I2 and Q1.
[1285] Next, FIGS. 100A through 100C illustrate a second example
that differs from the generation method of s1(t) and s2(t) from
FIGS. 97A through 97C is given for a case where the cyclic Q delay
is used. In FIGS. 100A through 100C, reference signs corresponding
to elements found in FIGS. 97A through 97C are identical (i.e., the
in-phase component and quadrature component of the baseband
signal).
[1286] Portion (a) of FIG. 100 indicates the in-phase component and
the quadrature component of the baseband signal obtained by the
mapper 9602 of FIG. 96. Portion (a) of FIG. 100 is identical to
portion (a) of FIG. 97. Explanations thereof are thus omitted.
[1287] Portion (b) of FIG. 100 illustrates the configuration of the
in-phase component and the quadrature component of the baseband
signals s1(t) and s2(t) prior to signal switching. As shown, the
baseband signal is allocated to s1(t) at times 2i+1, and allocated
to s2(t) at times 2i+2 (i being a non-zero positive integer).
[1288] Portion (c) of FIG. 100 illustrates a sample set of in-phase
components and quadrature components for the baseband signal when
signal switching is performed by the memory and signal switcher
9604 of FIG. 96. The main point of portion (c) of FIG. 100 (and
point of difference from portion (c) of FIG. 97) is that signal
switching occurs within s1(t) as well as s2(t). Accordingly, in
contrast to portion (b) of FIG. 100, Q1 and Q3 of s1(t) are
switched in portion (c) of FIG. 100, as are Q5 and Q7. Also, in
contrast to portion (b) of FIG. 100, Q2 and Q4 of s2(t) are
switched in portion (c) of FIG. 100, as are Q6 and Q8.
[1289] Thus, the first slot of s1(t) has an in-phase component I1
and a quadrature component Q3, and the first slot of s2(t) has an
in-phase component 12 and a quadrature component Q4. Also, the
second slot of s1(t) has an in-phase component 13 and a quadrature
component Q1, and the second slot of s2(t) has an in-phase
component 14 and a quadrature component Q4. The third and fourth
slots are as indicated in portion (c) of FIG. 100, and subsequent
slots are similar.
[1290] Then, N-slot precoded and phase changed modulated signals
r1(t) and r2(t) are obtained after applying the precoding and phase
change to the N-slot modulated signals s1(t) and s2(t). This point
is described elsewhere in the present disclosure.
[1291] FIG. 101 illustrates a configuration that differs from that
of FIG. 96 and is used to obtain the N-slot s1(t) and s2(t) from
FIGS. 100A through 100C. The mapper 9802 takes data 9801 and a
control signal 9804 as input and, in accordance with the modulation
method of the control signal 9804, for example, performs mapping in
consideration of the switching from FIG. 100, generates a mapped
signal (i.e., in-phase components and quadrature components of the
baseband signal) and generates modulated signal s1(t)(9803_A) and
modulated signal s2(t)(9803_B) from the mapped signal. Modulated
signal s1(t) (9803_A) is identical to modulated signal 9605_A from
FIG. 96, and modulated signal s2(t) (9803_B) is identical to
modulated signal 9605_B from FIG. 6. This is as indicated in
portion (c) of FIG. 100. Accordingly, the first slot of modulated
signal s1(t) (9803_A) takes (I1, Q3), the first slot of modulated
signal s2(t) (9803_B) takes (I2, Q4), the second slot of modulated
signal s1(t) (9803_A) takes (I3, Q1), the second slot of modulated
signal s2(t) (9803_B) takes (I4, Q2), and so on.
[1292] The generation method for the first slot (I1, Q3) of
modulated signal s1(t) (9803_A), the first slot (I2, Q4) of
modulated signal s2(t) (9803_B), the second slot (I3, Q1) of
modulated signal s1(t) (9803_A), and the second slot (I4, Q2) of
modulated signal s2(t) (9803_B) by the mapper 9802 from FIG. 101 is
described below, as a supplement.
[1293] The data 9801 indicated in FIG. 101 are made up of time 1
data b01, b11, b21, b31, time 2 data b02, b12, b22, b32, time 3
data b03, b13, b23, b33, and time 4 data b04, b14, b24, b34. The
mapper 9802 of FIG. 101 generates the aforementioned Q1, I2, Q2,
I3, Q3, I4, and Q4 from the data b01, b11, b21, b31, b02, b12, b22,
b32, b03, b13, b23, b33, b04. b14, b24, b34. Thus, the mapper 9802
of FIG. 101 is able to generate the modulated signals s1(t) and
s2(t) from I1, Q1, I2, Q2, 13, Q3, 14, and Q4.
[1294] FIG. 102 illustrates a configuration that differs from those
of FIGS. 96 and 101 and is used to obtain the N-slot s1(t) and
s2(t) from FIGS. 100A through 100C. A distributor 10201 takes data
9801 and the control signal 9804 as input, distributes the data in
accordance with the control signal 9804, and outputs first data
10202_A and second data 10202_B. The mapper 9901_A takes the first
data 10202_A and the control signal 9804 as input and, in
accordance with the modulation method of the control signal 9804,
for example, performs mapping in consideration of the switching
from FIG. 100, generates a mapped signal (i.e., in-phase components
and quadrature components of the baseband signal) and generates a
modulated signal s1(t)(9803_A) from the mapped signal. Similarly,
the mapper 9901_B takes second data 10202_B and the control signal
9804 as input and, in accordance with the modulation method of the
control signal 9804, for example, performs mapping in consideration
of the switching from FIG. 100, generates a mapped signal (i.e.,
in-phase components and quadrature components of the baseband
signal) and generates a modulated signal s2(t) (9803_B) from the
mapped signal.
[1295] Accordingly, the first slot of modulated signal s1(t)
(9803_A) takes (I1, Q3), the first slot of modulated signal s2(t)
(9803_B) takes (I2, Q4), the second slot of modulated signal s1(t)
(9803_A) takes (I3, Q1), the second slot of modulated signal s2(t)
(9803_B) takes (I4, Q2), and so on.
[1296] The generation method for the first slot (I1, Q3) of
modulated signal s1(t) (9803_A) and the first slot (I3, Q1) of
modulated signal s2(t) (9803_B) by the mapper 9901_A from FIG. 102
is described below, as a supplement. The data 9801 indicated in
FIG. 102 are made up of time 1 data b01, b11, b21, b31, time 2 data
b02, b12, b22, b32, time 3 data b03, b13, b23, b33, and time 4 data
b04, b14, b24, b34. The distributor 10201 outputs the time 1 data
b01, b11, b21, b31 and the time 3 data b03, b13, b23, b33, as the
first data 10202_A, and outputs the time 2 data b02, b12, b22, b32
and the time 4 data b04, b14, b24, b34 as the second data 10202_B
The mapper 9901_A of FIG. 102 generates the first slot as (I1, Q3)
and the second slot as (I3, Q1) from the data b01, b11, b21, b31,
b03, b13, b23, b33. The third slot and subsequent slots are
generated similarly.
[1297] The generation method for the first slot (I2, Q4) of
modulated signal s2(t) (9803_B) and the second slot (I4, Q2) by the
mapper 9901_B from FIG. 102 is described below. The mapper 9901_B
from FIG. 102 generates the first slot as (I2, Q4) and the second
slot as (I4, Q2) from the time 2 data b02, b12, b22, b32 and the
time 4 data b04, b14, b24, b34. The third slot and subsequent slots
are generated similarly.
[1298] Although two methods using cyclic Q delay are described
above, when the signals are switched among slot pairs as per FIGS.
97A through 97C, the demodulator (detector) of the reception device
is able to constrain the quantity of candidate signal points. This
has the merit of reducing the scope of calculation (circuit scope).
Also, when the signals are switched within s1(t) and s2(t), as per
FIGS. 100A through 100C, the demodulator (detector) of the
reception device encounters a large quantity of candidate signal
points. However, time diversity gain (or frequency diversity gain
when switching is performed with respect to the frequency domain)
is available, which as the merit of enabling further improvements
to the data reception quality.
[1299] Although the above description uses examples of a 16-QAM
modulation method, no limitation is intended. The same applies to
other modulation methods, such as QPSK, 8-QAM, 32-QAM, 64-QAM,
128-QAM, 256-QAM and so on.
[1300] Also, the cyclic Q delay method is not limited to the two
schemes given above. For example, either of the two schemes given
above may involve switching either of the quadrature component or
the in-phase component of the baseband signal. Also, while the
above describes switching performed at two times (e.g., switching
the quadrature components of the baseband signal at times 1 and 2),
the in-phase components and (or) the quadrature components of the
baseband signal may also be switched at a plurality of times.
Accordingly, when the in-phase components and quadrature components
of the baseband signal are generated and cyclic Q delay is
performed as in FIGS. 97A through 97C, then the in-phase component
of the baseband signal after cyclic Q delay at time i is Ii, and
the quadrature component of the baseband signal after cyclic Q
delay at time i is Qj (where i.noteq.j). Alternatively, the
in-phase component of the baseband signal after cyclic Q delay at
time i is Ij, and the quadrature component of the baseband signal
after cyclic Q delay at time i is Qi (where i j). Alternatively,
the in-phase component of the baseband signal after cyclic Q delay
at time i is Ij, and the quadrature component of the baseband
signal after cyclic Q delay at time i is Qk (where i.noteq.j,
i.noteq.k, j.noteq.k).
[1301] The precoding and phase change are then applied to the
modulated signals s1(t) (or s1(f), or s1(t,f)) and s2(t) (or s2(f)
or s2(t,f)) obtained by applying the above-described cyclic Q
delay. (Here, as described elsewhere, signal processing involving
phase change, power change, signal switching, and so on may be
applied at any step.) Here, the precoding and phase changing
application method used on the modulated signal obtained with the
cyclic Q delay may be any of the precoding and phase changing
methods described in the present disclosure.
Embodiment F1
[1302] In Embodiment E1, the transmission method for performing a
phase change on the precoded signals (or on precoded signals having
switched basebands) is applied to a broadcasting system conforming
to the DVB-T2 standard, and to a broadcasting system conforming to
another standard that is not DVB-T2. The present Embodiment
describes a situation where a sub-frame configuration based on the
transmit antenna configuration is applied to Embodiment E1.
[1303] FIG. 103A illustrates constraints pertaining to
single-antenna transmission (SISO) and to multi-antenna
transmission (MISO) in the DVB-T2 standard involving STBC. As
described in Non-Patent Literature 9, the DVB-T2 standard enables a
selection between transmitting the entire frame over a single
antenna and transmitting the entire frame over multiple antennas.
When transmitting over multiple antennas, the P1 symbol is
transmitted as an identical symbol over all antennas. That is, the
L1 signaling data carried by the P2 symbol and the entire PLP are
transmitted through a selected one of a single antenna and multiple
antennas.
[1304] FIG. 103B indicates a future standard to be desired. In
contrast to the preceding-generation DVB-T standard, a major
feature of the DVB-T2 standard is that transmission parameters such
as modulation method, coding rate, time interleaving depth, and so
on are independently selected for each PLP. Accordingly,
independently selecting whether each PLP is transmitted using a
single antenna or multiple antennas would be preferred. Further,
selecting whether the L1 signaling data is carried by the P2 symbol
using a single antenna or multiple antennas would also be
preferred.
[1305] As indicated in FIG. 103B, a pilot symbol insertion position
(pilot pattern) is a problem to be considered in order to enable
the presence of combined single-antenna and multi-antenna
transmission within a single frame. Non-Patent Literature 9
explains that the pilot pattern for scattered pilots (hereinafter,
SP), which are a type of pilot symbol, differs between
single-antenna (SISO) transmission and multi-antenna (MISO)
transmission. Thus, when a plurality of PLP#1 and PLP#2 are
combined at the same time (as a common OFDM symbol) as shown in
FIG. 75, and when PLP#1 is multi-antenna and PLP#2 is
single-antenna as shown in FIG. 77, the SP pilot pattern is
undefinable.
[1306] In order to resolve this problem, FIG. 104 illustrates a
sub-frame based on the configuration of the transmit antenna. As
shown, the frame includes a sub-frame for multi-antenna (MISO,
MIMO) transmission and a sub-frame for single-antenna (SISO)
transmission. Specifically, the PLPs for MISO and/or MIMO (e.g.,
the Common PLP, PLP#1) are gathered and a multi-antenna
transmission sub-frame is provided, such that a multi-antenna
transmission SP pilot pattern is applicable (when the number of
transmit antenna is the same, a common SP pilot pattern is usable
for MISO and MIMO). Meanwhile, the PLPs for SISO (e.g., PLP#2
through PLP#N) are gathered and a single-antenna transmission
sub-frame is provided such that a single-antenna transmission SP
pilot pattern is applicable.
[1307] As indicated in FIG. 78 and described in Embodiment E1, when
the signaling PLP (7801) is provided and control information needed
by the standard that is not the DVB-T2 standard (in whole or in
part, i.e., transmitted as the L1 Post-Signaling data and the
Signaling PLP) is transmitted, then as shown in FIG. 105, the
sub-frame configuration is providable in accordance with the
configuration of the transmit antenna.
[1308] Also, as indicated by FIG. 83 and described in Embodiment
E1, when the frame configuration uses both the first signaling data
(8301) and the second signaling data (8302), the same applies such
that a sub-frame configuration is providable based on the
configuration of the transmit antenna.
[1309] The above-described sub-frame configuration based on the
configuration of the transmit antenna enables the SP pilot pattern
to be defined and enables the realisation of a frame containing
combined single-antenna transmission and multi-antenna
transmission.
[1310] A transmission device configured to generate the sub-frame
based on the configuration of the transmit antenna as described
above is illustrated in FIGS. 76 and 85. However, in addition to
the points described in Embodiment E1, the frame configurator 7610
also generates the sub-frame based on the configuration of the
transmit antenna as described above.
[1311] Here, the characteristic feature is that when the
transmission method for performing the change of phase on precoded
(or precoded and switched) signals is selected, the signal
processor 7612 performs the change in phase on the precoded (or
precoded and switched) signals as indicated in FIGS. 6, 25 through
29, and 69. The signals so processed are output as processed
modulated signal 1 (7613_1) and processed modulated signal 2
(7613_2). However, this transmission method need not necessarily be
selected.
[1312] A reception device corresponding to the transmission method
and transmission device configured to generate the sub-frame based
on the configuration of the transmit antenna as described above is
illustrated in FIGS. 86 through 88. However, in addition to the
points described in Embodiment E2, the sub-frame configuration
based on the configuration of the transmit antenna enables the
channel fluctuation estimators (705_1, 705_2, 707_1, 707_2) to
appropriately estimate the channel fluctuations, despite
single-antenna transmission and multi-antenna transmission being
combined within a single frame.
[1313] Although the present Embodiment is based on the DVB-T2
standard, no limitation is intended. The Embodiment is applicable
to any transmission and reception of a combination of
single-antenna transmission and multi-antenna transmission.
Embodiment F2
[1314] Embodiment F1 described a situation where a sub-frame
configuration based on the transmit antenna configuration is
applied. In contrast to Embodiment F1, the present Embodiment
describes a transmit frame configuration enabling the receiver to
improve channel estimation.
[1315] FIG. 106 illustrates a transmit frame configuration
pertaining to the present Embodiment. Specifically, and in contrast
to the sub-frame configuration based on the configuration of the
transmit antenna illustrated in FIG. 104 of Embodiment F1, the
present Embodiment describes a transmit frame configuration in
which, for each sub-frame, a sub-frame starting symbol is applied
as the leading OFDM symbol and a sub-frame closing symbol is
applied as the trailing OFDM symbol. However, a selection is
possible as to whether or not the sub-frame starting symbol and the
sub-frame closing symbol are provided independently for each
sub-frame, and as to whether or not the sub-frame starting symbol
and the sub-frame closing symbol are independent from one another
in each sub-frame.
[1316] FIG. 107 illustrates an example of a sub-frame starting
symbol and a sub-frame closing symbol. As shown, the sub-frame
starting symbol and the sub-frame closing symbol have greater SP
density than other OFDM symbols. Specifically, SP in the sub-frame
starting symbol and the sub-frame closing symbol are located at all
sub-carrier positions where SP are possible.
[1317] Another sub-frame, a P2 symbol, or a P1 symbol occurs before
the sub-frame starting symbol and after the sub-frame closing
symbol. These use a different SP pilot pattern (the P1 symbol uses
no SP pilot pattern at all). Thus, the transmission path (channel
fluctuation) estimation process by the reception device is unable
to perform a interpolation process that crosses different sub-frame
in the time direction (i.e., the OFDM symbol direction).
Accordingly, when the SP pilot pattern for the other OFDM symbols
is defined according to the same rule as the leading and trailing
OFDM symbols of the sub-frame, the accuracy of interpolation of the
leading portion and the trailing portion of the sub-frame
worsens.
[1318] As shown in FIG. 107, providing the sub-frame starting
symbol and the sub-frame closing symbol enables the OFDM symbols to
have SP at all sub-carrier positions where SP are possible, i.e.,
at all sub-carrier positions where time-direction interpolation
process is applicable. Thus, the accuracy of interpolation of the
leading portion and the trailing portion of the sub-frame is
improved.
[1319] The sub-frame starting symbol and sub-frame closing symbol
may also be provided when, as illustrated in FIG. 105 and described
in Embodiment F1, the signaling PLP (7801) is provided and control
information needed by the standard that is not the DVB-T2 standard
(in whole or in part, i.e., transmitted as the L1 Post-Signaling
data and the Signaling PLP) is transmitted.
[1320] The sub-frame starting symbol and the sub-frame closing
symbol may also be provided when, as illustrated in FIG. 83 and
described in Embodiment E1, the first signaling data (8301) and the
second signaling data (8302) are used in the frame
configuration.
[1321] The transmit frame configuration using the sub-frame
starting symbol and the sub-frame closing symbol described above
enables improvements to the channel estimation by the receiver.
[1322] The transmission device generating the transmit frame
configuration using the sub-frame starting symbol and the sub-frame
closing symbol described above is as described in FIGS. 76 and 85.
However, in addition to the points described in Embodiments E1 and
F1, the frame configurator 7610 also generates the transmit frame
configuration using the sub-frame starting symbol and the sub-frame
closing symbol described above.
[1323] Here, the characteristic feature is that when the
transmission method for performing the change of phase on precoded
(or precoded and switched) signals is selected, the signal
processor 7612 performs the change in phase on the precoded (or
precoded and switched) signals as indicated in FIGS. 6, 25 through
29, and 69. The signals so processed are output as processed
modulated signal 1 (7613_1) and processed modulated signal 2
(7613_2). However, this transmission method need not necessarily be
selected.
[1324] The reception device corresponding to the transmission
method and the transmission device generating the transmit frame
configuration using the sub-frame starting symbol and the sub-frame
closing symbol described above is as described in FIGS. 86 through
88. However, in addition to the points described in Embodiments E2
and F1, the transmit frame configuration that uses the sub-frame
starting symbol and the sub-frame closing symbol enables the
channel fluctuation estimators (705_1, 705_2, 707_1, 707_2) to more
precisely estimate the channel fluctuations for the leading portion
and the trailing portion of the sub-frame, despite single-antenna
transmission and multi-antenna transmission being combined within
the frame.
[1325] Although the present Embodiment is based on the DVB-T2
standard, no limitation is intended. The Embodiment is applicable
to any transmission and reception of a combination of
single-antenna transmission and multi-antenna transmission.
Embodiment F3
[1326] Embodiment F 1 described a situation where a sub-frame
configuration based on the transmit antenna configuration is
applied. The present Embodiment describes a situation where the
polarization of the transmit antenna is taken into consideration,
in addition to the configuration thereof.
[1327] FIGS. 108A through 108D illustrate various types of
broadcast networks. FIG. 108A, in particular, illustrates an actual
DVB-T2 service network (SISO) currently used in the United Kingdom.
The transmit and receive antennas are each single antennas having V
(vertical) polarization.
[1328] FIG. 108B illustrates a distributed-MISO system employing an
existing transmit antenna. In contrast to the SISO broadcasting
network that uses V polarization from FIG. 108A, FIG. 108B
illustrates a MISO broadcasting network that uses V polarization in
which different transmit stations are paired. This configuration
also supports SISO.
[1329] FIG. 108C illustrates a co-sited-MIMO configuration. In
contrast to the SISO broadcasting network that uses V polarization
from FIG. 108A, FIG. 108C illustrates a MIMO broadcasting network
that uses V-H polarization in which an H (horizontal) antenna is
added to serve as a transmit or receive antenna. This configuration
supports MISO as well as SISO.
[1330] FIG. 108D illustrates a configuration in which
distributed-MISO and co-sited-MIMO are combined.
[1331] Like the above, future broadcasting networks are likely to
incorporate polarization in a variety of forms. Preferably, each
broadcast service provider is able to freely choose between these
forms and implement them at any time. Thus, future broadcasting
standards ought to support all forms of broadcasting networks
mentioned above.
[1332] Incidentally, as indicated by FIG. 108D, V/H transmission
and V/V transmission involve different channel characteristics,
despite the multi-antenna transmission occurring with identical
number of transmit antennas. Thus, when identical OFDM symbols are
combined, a problem arises in that the receiver is unable to
perform channel estimation.
[1333] In order to resolve this problem, FIG. 109 illustrates a
sub-frame based on the configuration of the transmit antenna
(taking polarization into consideration). As shown in FIG. 109,
each frame is provided with a V/H-MIMO sub-frame, a V/V-MISO
sub-frame, and a V-SISO sub-frame. Specifically, the PLPs (e.g.,
Common PLP) for V/H-MIMO are gathered and a V/H-MIMO sub-frame is
provided, such that a V/H-MIMO SP pilot pattern is applicable.
Likewise, the PLPs (e.g. PLP#1) for V/V-MISO are gathered and a
V/V-MISO sub-frame is provided, such that a V/V-MISO SP pilot
pattern is applicable. Similarly, the PLPs (e.g., PLP#2 through
PLP#N) for V-SISO are gathered and a V-SISO sub-frame is provided,
such that a V-SISO SP pilot pattern is applicable.
[1334] As indicated in FIG. 78 and described in Embodiment E1, when
the signaling PLP (7801) is provided and control information needed
by the standard that is not the DVB-T2 standard (in whole or in
part, i.e., transmitted as the L1 Post-Signaling data and the
Signaling PLP) is transmitted, then the sub-frame configuration is
providable in accordance with the configuration of the transmit
antenna (taking the polarization into consideration).
[1335] Also, as indicated by FIG. 83 and described in Embodiment
E1, when the frame configuration uses both the first signaling data
(8301) and the second signaling data (8302), the same applies such
that a sub-frame configuration is providable based on the
configuration of the transmit antenna (taking the polarization into
consideration).
[1336] The sub-frame configuration based on the transmit antenna
configuration (taking the polarization into consideration)
described above enables the receiver to perform channel
estimation.
[1337] A transmission device configured to generate the sub-frame
based on the configuration of the transmit antenna as described
above (taking the polarization into consideration) is illustrated
in FIGS. 76 and 85. However, in addition to the points described in
Embodiment E1, the frame configurator 7610 also generates the
sub-frame based on the configuration of the transmit antenna as
described above (taking the polarization into consideration).
[1338] Here, the characteristic feature is that when the
transmission method for performing the change of phase on precoded
(or precoded and switched) signals is selected, the signal
processor 7612 performs the change in phase on the precoded (or
precoded and switched) signals as indicated in FIGS. 6, 25 through
29, and 69. The signals so processed are output as processed
modulated signal 1 (7613_1) and processed modulated signal 2
(7613_2). However, this transmission method need not necessarily be
selected.
[1339] A reception device corresponding to the transmission method
and transmission device configured to generate the sub-frame based
on the configuration of the transmit antenna as described above
(taking the polarization into consideration) is illustrated in
FIGS. 86 through 88. However, in addition to the points described
in Embodiment E2, the sub-frame configuration based on the
configuration of the transmit antenna (taking the polarization into
consideration) enables the channel fluctuation estimators (705_1,
705_2, 707_1, 707_2) to appropriately estimate the channel
fluctuations, despite transmission methods using different
polarizations being combined in the frame.
[1340] Although the present Embodiment is based on the DVB-T2
standard, no limitation is intended. The Embodiment is applicable
to any transmission method supporting different polarizations.
[1341] Also, although FIG. 109 illustrates a specific example of
sub-frame configuration, no limitation is intended. The
configuration may include any of a H-SISO sub-frame, a V/V-MIMO
sub-frame, and a V/H-MISO sub-frame.
[1342] Also, although V polarization and H polarization are
described as the contrasting polarizations, no limitation is
intended thereto.
Embodiment F4
[1343] Embodiment F3 described a situation where a sub-frame
configuration based on the transmit antenna configuration is
applied (taking the polarization into consideration). In contrast
to Embodiment F3, the present Embodiment describes a transmit frame
configuration enabling the receiver to improve channel
estimation.
[1344] FIG. 110 illustrates a transmit frame configuration
pertaining to the present Embodiment. Specifically, and in contrast
to the sub-frame configuration based on the configuration of the
transmit antenna (taking the polarization into consideration)
illustrated in FIG. 109 of Embodiment F3, the present Embodiment
describes a transmit frame configuration in which, for each
sub-frame, a sub-frame starting symbol is applied as the leading
OFDM symbol and a sub-frame closing symbol is applied as the
trailing OFDM symbol. However, a selection is possible as to
whether or not the sub-frame starting symbol and the sub-frame
closing symbol are provided independently for each sub-frame, and
as to whether or not the sub-frame starting symbol and the
sub-frame closing symbol are independent from one another in each
sub-frame.
[1345] As shown in FIG. 107 and described in Embodiment F2,
providing the sub-frame starting symbol and the sub-frame closing
symbol enables the OFDM symbols to have SP at all sub-carrier
positions where SP are possible, i.e., at all sub-carrier positions
where time-direction interpolation process is applicable. Thus, the
accuracy of interpolation of the leading portion and the trailing
portion of the sub-frame is improved.
[1346] The sub-frame starting symbol and sub-frame closing symbol
may also be provided when, as illustrated in FIG. 105 and described
in Embodiment F1, the signaling PLP (7801) is provided and control
information needed by the standard that is not the DVB-T2 standard
(in whole or in part, i.e., transmitted as the L1 Post-Signaling
data and the Signaling PLP) is transmitted.
[1347] The sub-frame starting symbol and the sub-frame closing
symbol may also be provided when, as illustrated in FIG. 83 and
described in Embodiment E1, the first signaling data (8301) and the
second signaling data (8302) are used in the frame
configuration.
[1348] The transmit frame configuration using the sub-frame
starting symbol and the sub-frame closing symbol described above
enables improvements to the channel estimation by the receiver.
[1349] The transmission device generating the transmit frame
configuration using the sub-frame starting symbol and the sub-frame
closing symbol described above is as described in FIGS. 76 and 85.
However, in addition to the points described in Embodiments E1 and
F3, the frame configurator 7610 also generates the transmit frame
configuration using the sub-frame starting symbol and the sub-frame
closing symbol described above.
[1350] Here, the characteristic feature is that when the
transmission method for performing the change of phase on precoded
(or precoded and switched) signals is selected, the signal
processor 7612 performs the change in phase on the precoded (or
precoded and switched) signals as indicated in FIGS. 6, 25 through
29, and 69. The signals so processed are output as processed
modulated signal 1 (7613_1) and processed modulated signal 2
(7613_2). However, this transmission method need not necessarily be
selected.
[1351] The reception device corresponding to the transmission
method and the transmission device generating the transmit frame
configuration using the sub-frame starting symbol and the sub-frame
closing symbol described above is as described in FIGS. 86 through
88. However, in addition to the points described in Embodiments E2
and F3, the transmit frame configuration that uses the sub-frame
starting symbol and the sub-frame closing symbol enables the
channel fluctuation estimators (705_1, 705_2, 707_1, 707_2) to more
precisely estimate the channel fluctuations for the leading portion
and the trailing portion of the sub-frame, despite transmission
methods using different polarizations being combined within the
frame.
[1352] Although the present Embodiment is based on the DVB-T2
standard, no limitation is intended. The Embodiment is applicable
to any transmission method supporting different polarizations.
[1353] Also, although FIG. 110 illustrates a specific example of a
transmit frame configuration, no limitation is intended. The
configuration may include any of an H-SISO sub-frame, a V/V-MIMO
sub-frame, and a V/H-MISO sub-frame.
[1354] Also, although V polarization and H polarization are
described as the contrasting polarizations, no limitation is
intended thereto.
[1355] Embodiments F 1 through F4, described above, discuss
sub-frame configurations corresponding to a frame. The content of
Embodiments F1 through F4 may be similarly applied to frame
configurations corresponding to a super-frame, to short frame
configurations corresponding to a long frame, and the like.
[1356] Although applying Embodiments F1 through F4 to a super-frame
is surely obvious to those skilled in the art, a specific example
is here provided. Namely, the T2 frames and future extension frames
(hereinafter, FEF) making up the super-frames of the DVB-T2
standard are considered to be the sub-frames described in each of
Embodiments F1 through F4, and the data transmitted in one of the
T2 frames or one of the FEFs is fixed as being one of SISO and MISO
and/or MIMO. Then, the data transmitted by each of the frames is
gathered into data for SISO and data for MISO and/or MIMO, and the
frames are generated accordingly.
[1357] Also, a starting symbol and a closing symbol are inserted
between the sub-frames discussed in Embodiments F1 through F4, so
as to clarify the distinction between sub-frames. On a
frame-by-frame level, a P1 symbol, which is easy to identify by the
receiver at the head of the frame, is inserted at the head of the
frame, and is followed by a P2 symbol having higher SP density than
other OFDM symbols. As such, the starting symbol is of course
unneeded when obvious in the field to which the present disclosure
applies. However, the symbol being unneeded signifies only that the
distinction between frames is sufficiently clear so as to make the
symbol unnecessary. There is no harm in inserting the symbol as a
way to further clarify and stabilise transmission. In such
circumstances, the starting symbol is inserted at the head of the
frame (before the P1 symbol).
Embodiment G1
[1358] Embodiment F 1 described a situation where a sub-frame
configuration based on the transmit antenna configuration is
applied. The present Embodiment describes a situation where the
transmission power of the transmit antenna is taken into
consideration, in addition to the configuration thereof.
[1359] As indicated in the bottom-right portion of FIG. 111,
situations arise where otherwise-identical multi-antenna
transmission may involve antennas each having different
transmission power. Different transmission power leads to different
channel characteristics. Thus, when these are combined in identical
OFDM symbols, a problem arises in that the receiver is unable to
perform channel estimation.
[1360] In order to resolve this problem, FIG. 111 illustrates a
sub-frame configuration based on the configuration of the transmit
antenna (taking transmission power into consideration). As shown,
the frame includes a sub-frame for multi-antenna (MISO, MIMO)-pwr1
transmission, a sub-frame for multi-antenna (MISO, MIMO)-pwr2
transmission, and a sub-frame for single-antenna (SISO)
transmission. Specifically, the PLPs among the MISO and/or MIMO
PLPs for which the power of both transmit antennas 1 and 2 is P/2
(e.g., Common PLP) are gathered and a multi-antenna
transmission-pwr1 sub-frame is provided, such that a multi-antenna
transmission-pwr1 SP pilot pattern is applicable (a common SP pilot
pattern is usable for MISO and MIMO when the quantity of transmit
antennas is equal and the transmission power is uniform). Also, the
PLPs among the MISO and MIMO PLPs for which the power of the
transmit antennas is 3P/4 for antenna 1 and P/4 for antenna 2
(e.g., PLP#1) are gathered and a multi-antenna transmission-pwr2
sub-frame is provided, such that a multi-antenna transmission-pwr2
SP pilot pattern is applicable. Meanwhile, the PLPs for SISO (e.g.,
PLP#2 through PLP#N) are gathered and a single-antenna transmission
sub-frame is provided such that a single-antenna transmission SP
pilot pattern is applicable. However, in this example, the PLPs for
SISO all have identical transmission power. When the transmission
power differs, a different sub-frame is needed for each value.
[1361] As indicated in FIG. 78 and described in Embodiment E1, when
the signaling PLP (7801) is provided and control information needed
by the standard that is not the DVB-T2 standard (in whole or in
part, i.e., transmitted as the L1 Post-Signaling data and the
Signaling PLP) is transmitted, then the sub-frame configuration is
providable in accordance with the configuration of the transmit
antenna (taking the transmission power into consideration).
[1362] Also, as indicated by FIG. 83 and described in Embodiment
E1, when the frame configuration uses both the first signaling data
(8301) and the second signaling data (8302), the same applies such
that a sub-frame configuration is providable based on the
configuration of the transmit antenna (taking the transmission
power into consideration).
[1363] The sub-frame configuration based on the transmit antenna
configuration (taking the transmission power into consideration)
described above enables the receiver to perform channel
estimation.
[1364] A transmission device configured to generate the sub-frame
based on the configuration of the transmit antenna as described
above (taking the transmission power into consideration) is
illustrated in FIGS. 76 and 85. However, in addition to the points
described in Embodiment E1, the frame configurator 7610 also
generates the sub-frame based on the configuration of the transmit
antenna as described above (taking the transmission power into
consideration).
[1365] Here, the characteristic feature is that when the
transmission method for performing the change of phase on precoded
(or precoded and switched) signals is selected, the signal
processor 7612 performs the change in phase on the precoded (or
precoded and switched) signals as indicated in FIGS. 6, 25 through
29, and 69. The signals so processed are output as processed
modulated signal 1 (7613_1) and processed modulated signal 2
(7613_2). However, this transmission method need not necessarily be
selected.
[1366] A reception device corresponding to the transmission method
and transmission device configured to generate the sub-frame based
on the configuration of the transmit antenna as described above
(taking the transmission power into consideration) is illustrated
in FIGS. 86 through 88. However, in addition to the points
described in Embodiment E2, the sub-frame configuration based on
the configuration of the transmit antenna (taking the transmission
power into consideration) enables the channel fluctuation
estimators (705_1, 705_2, 707_1, 707_2) to appropriately estimate
the channel fluctuations, despite transmission methods using
different transmission power being combined in the frame for the
same multi-antenna transmission or single-antenna transmission.
[1367] Although the present Embodiment is based on the DVB-T2
standard, no limitation is intended. The Embodiment is applicable
to any transmission and reception of a combination of
single-antenna transmission and multi-antenna transmission.
[1368] Also, although FIG. 111 illustrates an example of a
sub-frame configuration, no limitation is intended.
Embodiment G2
[1369] Embodiment G1 described a situation where a sub-frame
configuration based on the transmit antenna configuration is
applied (taking the transmission power into consideration). In
contrast to Embodiment G1, the present Embodiment describes a
transmit frame configuration enabling the receiver to improve
channel estimation.
[1370] FIG. 112 illustrates a transmit frame configuration
pertaining to the present Embodiment. Specifically, and in contrast
to the sub-frame configuration based on the configuration of the
transmit antenna (taking the transmission power into consideration)
illustrated in FIG. 110 of Embodiment G1, the present Embodiment
describes a transmit frame configuration in which, for each
sub-frame, a sub-frame starting symbol is applied as the leading
OFDM symbol and a sub-frame closing symbol is applied as the
trailing OFDM symbol. However, a selection is possible as to
whether or not the sub-frame starting symbol and the sub-frame
closing symbol are provided independently for each sub-frame, and
as to whether or not the sub-frame starting symbol and the
sub-frame closing symbol are independent from one another in each
sub-frame.
[1371] As shown in FIG. 107 and described in Embodiment F2,
providing the sub-frame starting symbol and the sub-frame closing
symbol enables the OFDM symbols to have SP at all sub-carrier
positions where SP are possible, i.e., at all sub-carrier positions
where time-direction interpolation process is applicable. Thus, the
accuracy of interpolation of the leading portion and the trailing
portion of the sub-frame is improved.
[1372] The sub-frame starting symbol and sub-frame closing symbol
may also be provided when, as illustrated in FIG. 78 and described
in Embodiment E1, the signaling PLP (7801) is provided and control
information needed by the standard that is not the DVB-T2 standard
(in whole or in part, i.e., transmitted as the L1 post-signaling
data and the signaling PLP) is transmitted.
[1373] The sub-frame starting symbol and the sub-frame closing
symbol may also be provided when, as illustrated in FIG. 83 and
described in Embodiment E1, the first signaling data (8301) and the
second signaling data (8302) are used in the frame
configuration.
[1374] The transmit frame configuration using the sub-frame
starting symbol and the sub-frame closing symbol described above
enables improvements to the channel estimation by the receiver.
[1375] The transmission device generating the transmit frame
configuration using the sub-frame starting symbol and the sub-frame
closing symbol described above is as described in FIGS. 76 and 85.
However, in addition to the points described in Embodiments E1 and
G1, the frame configurator 7610 also generates the transmit frame
configuration using the sub-frame starting symbol and the sub-frame
closing symbol described above.
[1376] Here, the characteristic feature is that when the
transmission method for performing the change of phase on precoded
(or precoded and switched) signals is selected, the signal
processor 7612 performs the change in phase on the precoded (or
precoded and switched) signals as indicated in FIGS. 6, 25 through
29, and 69. The signals so processed are output as processed
modulated signal 1 (7613_1) and processed modulated signal 2
(7613_2). However, this transmission method need not necessarily be
selected.
[1377] The reception device corresponding to the transmission
method and the transmission device generating the transmit frame
configuration using the sub-frame starting symbol and the sub-frame
closing symbol described above is as described in FIGS. 86 through
88. However, in addition to the points described in Embodiments E2
and G1, the transmit frame configuration using the sub-frame
starting symbol and the sub-frame closing symbol enables the
channel fluctuation estimators (705_1, 705_2, 707_1, 707_2) to more
precisely estimate the channel fluctuations for the leading portion
and the trailing portion of the sub-frame, despite transmission
methods using different transmission power being combined in the
frame for the same multi-antenna transmission or single-antenna
transmission.
[1378] Although the present Embodiment is described as based on the
DVB-T2 standard, no limitation is intended. The Embodiment is also
applicable to supporting a transmission method in which each
antenna has a different transmission power, within
otherwise-identical multi-antenna transmission or single-antenna
transmission.
[1379] Also, although FIG. 112 illustrates an example of a transmit
frame configuration , no limitation is intended.
Embodiment G3
[1380] Embodiment F3 described a situation where a sub-frame
configuration based on the transmit antenna configuration is
applied (taking the polarization into consideration). The present
Embodiment describes a situation where the transmission power of
the transmit antenna is taken into consideration (along with the
polarization), in addition to the configuration thereof.
[1381] As indicated in the bottom-right portion of FIG. 113,
situations arise where otherwise-identical V/V-MISO transmission
may involve antennas each having different transmission power.
Different transmission power leads to different channel
characteristics. Thus, when identical OFDM symbols are combined, a
problem arises in that the receiver is unable to perform channel
estimation.
[1382] In order to resolve this problem, FIG. 113 illustrates a
sub-frame configuration based on the configuration of the transmit
antenna (taking the polarization and the transmission power into
consideration). As shown in FIG. 113, each frame is provided with a
V/H-MIMO sub-frame, a V-SISO sub-frame, a V/V-MISO-pwr1 sub-frame,
and a V/V-MISO-pwr2 sub-frame. Specifically, the PLPs among the
V/V-MISO PLPs for which the power of both transmit antennas 1 and 2
is P/2 (e.g., PLP#2) are gathered and a V/V-MISO-pwr1 sub-frame is
provided, such that a V/V-MISO-pwr1 SP pilot pattern is applicable.
Similarly, the PLPs among the V/V-MISO PLPs for which the power of
the transmit antennas 1 and 2 is 3P/4 and P/4, respectively (e.g.,
PLP#3 through PLP#N) are gathered and a V/V-MISO-pwr2 sub-frame is
provided, such that a V/V-MISO-pwr2 SP pilot pattern is applicable.
Likewise, the PLPs (e.g., Common PLP) for the V/H-MIMO are gathered
and a V/H-MIMO sub-frame is provided, such that a V/H-MIMO SP pilot
pattern is applicable. Also, the PLPs (e.g., PLP#1) for V-SISO are
gathered and a V-SISO sub-frame is provided, such that a V-SISO SP
pilot pattern is applicable. However, these examples are given for
cases where only one PLP is available for V/H-MIMO and V-SISO.
Additional and differing sub-frame are needed when PLPs are
available for multiple different transmission powers.
[1383] As indicated in FIG. 78 and described in Embodiment E1, when
the signaling PLP (7801) is provided and control information needed
by the standard that is not the DVB-T2 standard (in whole or in
part, i.e., transmitted as the L1 Post-Signaling data and the
Signaling PLP) is transmitted, then the sub-frame configuration is
providable in accordance with the configuration of the transmit
antenna (taking the polarization and the transmission power into
consideration).
[1384] Also, as indicated by FIG. 83 and described in Embodiment
E1, when the frame configuration uses both the first signaling data
(8301) and the second signaling data (8302), the same applies such
that a sub-frame configuration is providable based on the
configuration of the transmit antenna (taking the polarization and
the transmission power into consideration).
[1385] The sub-frame configuration based on the transmit antenna
configuration (taking the transmission power and the polarization
into consideration) described above enables the receiver to perform
channel estimation.
[1386] A transmission device configured to generate the sub-frame
based on the configuration of the transmit antenna as described
above (taking the transmission power and the polarization into
consideration) is illustrated in FIGS. 76 and 85. However, in
addition to the points described in Embodiment E1, the frame
configurator 7610 also generates the sub-frame based on the
configuration of the transmit antenna as described above (taking
the transmission power and the polarization into
consideration).
[1387] Here, the characteristic feature is that when the
transmission method for performing the change of phase on precoded
(or precoded and switched) signals is selected, the signal
processor 7612 performs the change in phase on the precoded (or
precoded and switched) signals as indicated in FIGS. 6, 25 through
29, and 69. The signals so processed are output as processed
modulated signal 1 (7613_1) and processed modulated signal 2
(7613_2). However, this transmission method need not necessarily be
selected.
[1388] A reception device corresponding to the transmission method
and transmission device configured to generate the sub-frame based
on the configuration of the transmit antenna as described above
(taking the transmission power and the polarization into
consideration) is illustrated in FIGS. 86 through 88. However, in
addition to the points described in Embodiment E2, the sub-frame
configuration based on the configuration of the transmit antenna
(taking the transmission power and the polarization into
consideration) enables the channel fluctuation estimators (705_1,
705_2, 707_1, 707_2) to appropriately estimate the channel
fluctuations, despite transmission methods using different
transmission power being combined in the frame for the same
multi-antenna transmission or single-antenna transmission using
identical polarization.
[1389] Although the present Embodiment is described as based on the
DVB-T2 standard, no limitation is intended. The Embodiment is also
applicable to supporting a transmission method in which each
antenna has a different transmission power, within
otherwise-identical multi-antenna transmission or single-antenna
transmission using identical polarization.
[1390] Also, although FIG. 113 illustrates an example of a
sub-frame configuration, no limitation is intended.
[1391] Also, although V polarization and H polarization are
described as the contrasting polarizations, no limitation is
intended thereto.
Embodiment G4
[1392] Embodiment G3 described a situation where a sub-frame
configuration based on the transmit antenna configuration is
applied (taking the transmission power and the polarization into
consideration). In contrast to Embodiment G3, the present
Embodiment describes a transmit frame configuration enabling the
receiver to improve channel estimation.
[1393] FIG. 114 illustrates a transmit frame configuration
pertaining to the present Embodiment. Specifically, and in contrast
to the sub-frame configuration based on the configuration of the
transmit antenna (taking the transmission power and the
polarization into consideration) illustrated in FIG. 113 of
Embodiment G3, the present Embodiment describes a transmit frame
configuration in which, for each sub-frame, a sub-frame starting
symbol is applied as the leading OFDM symbol and a sub-frame
closing symbol is applied as the trailing OFDM symbol. However, a
selection is possible as to whether or not the sub-frame starting
symbol and the sub-frame closing symbol are provided independently
for each sub-frame, and as to whether or not the sub-frame starting
symbol and the sub-frame closing symbol are independent from one
another in each sub-frame.
[1394] As shown in FIG. 107 and described in Embodiment F2,
providing the sub-frame starting symbol and the sub-frame closing
symbol enables the OFDM symbols to have SP at all sub-carrier
positions where SP are possible, i.e., at all sub-carrier positions
where time-direction interpolation process is applicable. Thus, the
accuracy of interpolation of the leading portion and the trailing
portion of the sub-frame is improved.
[1395] The sub-frame starting symbol and sub-frame closing symbol
may also be provided when, as illustrated in FIG. 78 and described
in Embodiment E1, the signaling PLP (7801) is provided and control
information needed by the standard that is not the DVB-T2 standard
(in whole or in part, i.e., transmitted as the L1 post-signaling
data and the signaling PLP) is transmitted.
[1396] The sub-frame starting symbol and the sub-frame closing
symbol may also be provided when, as illustrated in FIG. 83 and
described in Embodiment E1, the first signaling data (8301) and the
second signaling data (8302) are used in the frame
configuration.
[1397] The transmit frame configuration using the sub-frame
starting symbol and the sub-frame closing symbol described above
enables improvements to the channel estimation by the receiver.
[1398] The transmission device generating the transmit frame
configuration using the sub-frame starting symbol and the sub-frame
closing symbol described above is as described in FIGS. 76 and 85.
However, in addition to the points described in Embodiments E1 and
G3, the frame configurator 7610 also generates the transmit frame
configuration using the sub-frame starting symbol and the sub-frame
closing symbol described above.
[1399] Here, the characteristic feature is that when the
transmission method for performing the change of phase on precoded
(or precoded and switched) signals is selected, the signal
processor 7612 performs the change in phase on the precoded (or
precoded and switched) signals as indicated in FIGS. 6, 25 through
29, and 69. The signals so processed are output as processed
modulated signal 1 (7613_1) and processed modulated signal 2
(7613_2). However, this transmission method need not necessarily be
selected.
[1400] The reception device corresponding to the transmission
method and the transmission device generating the transmit frame
configuration using the sub-frame starting symbol and the sub-frame
closing symbol described above is as described in FIGS. 86 through
88. However, in addition to the points described in Embodiments E2
and G3, the transmit frame configuration using the sub-frame
starting symbol and the sub-frame closing symbol enables the
channel fluctuation estimators (705_1, 705_2, 707_1, 707_2) to more
precisely estimate the channel fluctuations for the leading portion
and the trailing portion of the sub-frame, despite transmission
methods using different transmission power being combined in the
frame for the same multi-antenna transmission or single-antenna
transmission using identical polarization.
[1401] Although the present Embodiment is described as based on the
DVB-T2 standard, no limitation is intended. The Embodiment is also
applicable to supporting a transmission method in which each
antenna has a different transmission power, within
otherwise-identical multi-antenna transmission or single-antenna
transmission using identical polarization.
[1402] Also, although FIG. 114 illustrates an example of a transmit
frame configuration, no limitation is intended.
[1403] Also, although V polarization and H polarization are
described as the contrasting polarizations, no limitation is
intended thereto.
[1404] Embodiments G1 through G4, described above, discuss
sub-frame configurations corresponding to a frame. The content of
Embodiments G1 through G4 may be similarly applied to frame
configurations corresponding to a super-frame, to short frame
configurations corresponding to a long frame, and the like.
[1405] Although applying Embodiments G1 through G4 to a super-frame
is surely obvious to those skilled in the art, a specific example
is here provided. Namely, the T2 frames and future extension frames
(hereinafter, FEF) making up the super-frames of the DVB-T2
standard are considered to be the sub-frames described in each of
Embodiments G1 through G4, and the data transmitted in one of the
T2 frames or one of the FEFs is fixed as being one of SISO and MISO
and/or MIMO. Then, the transmit data transmitted in each frame are
one of: gathered as SISO data in a frame generated for uniform
transmission power when transmitted by the antenna; and gathered as
MISO and/or MIMO data in a frame generated for uniform transmission
power when transmitted by the antenna.
[1406] Although Embodiments G1 through G4 describe the starting
symbol and the closing symbol as being inserted in order to clarify
the distinction between sub-frames, on a frame-by-frame level, a P1
symbol, which is easy to identify by the receiver at the head of
the frame, is inserted at the head of the frame, and is followed by
a P2 symbol having higher SP density than other OFDM symbols. As
such, the starting symbol is of course unneeded when obvious in the
field to which the present disclosure applies. However, the symbol
being unneeded signifies only that the distinction between frames
is sufficiently clear so as to make the symbol unnecessary. There
is no harm in inserting the symbol as a way to further clarify and
stabilise transmission. In such circumstances, the starting symbol
is inserted at the head of the frame (before the P1 symbol).
[1407] The present invention is widely applicable to wireless
systems that transmit different modulated signals from a plurality
of antennas, such as an OFDM-MIMO system. Also, the present
invention is also applicable in a wired system having multiple
connections (e.g., a power line communication system, a fibre-optic
system, a digital subscriber line system, and so on) when MIMO
transmission is used, and the modulated signals described in the
present document are applied. The modulated signals may also be
transmitted from a plurality of transmission locations.
REFERENCE SIGNS LIST
[1408] 302A, 302B Encoders
[1409] 304A, 304B Interleavers
[1410] 306A, 306B Mappers
[1411] 314 Signal processing scheme information generator
[1412] 308A, 308B Weighting compositors
[1413] 310A, 310B Wireless units
[1414] 312A, 312B Antennas
[1415] 317A, 317B Phase changers
[1416] 402 Encoder
[1417] 404 Distributor
[1418] 504#1, 504#2 Transmit antennas
[1419] 505#1, 505#2 Receive antennas
[1420] 600 Weighting unit
[1421] 701_X, 701_Y Antennas
[1422] 703_X, 703_Y Wireless units
[1423] 705_1 Channel fluctuation estimator
[1424] 705_2 Channel fluctuation estimator
[1425] 707_1 Channel fluctuation estimator
[1426] 707_2 Channel fluctuation estimator
[1427] 709 Control information decoder
[1428] 711 Signal processor
[1429] 803 Inner MIMO detector
[1430] 805A, 805B Log-likelihood calculators
[1431] 807A, 807B Deinterleavers
[1432] 809A, 809B Log-likelihood ratio calculator
[1433] 811A, 811B Soft-in/soft-out decoders
[1434] 813A, 813B Interleavers
[1435] 815 Memory
[1436] 819 Coefficient generator
[1437] 901 Soft-in/soft-out decoder
[1438] 903 Distributor
[1439] 1201A, 1201B OFDM-related processors
[1440] 1302A, 1302A Serial-to-parallel converters
[1441] 1304A, 1304B Reorderers
[1442] 1306A, 1306B Inverse Fast Fourier Transform units
[1443] 1308A, 1308B Wireless units
* * * * *