U.S. patent application number 11/909711 was filed with the patent office on 2009-06-11 for transmission apparatus, reception apparatus, mobile communications system and transmission control method.
This patent application is currently assigned to NTT DOCOMO, INC.. Invention is credited to Hiroyuki Atarashi, Kenichi Higuchi, Yoshiaki Ofuji, Mamoru Sawahashi.
Application Number | 20090147748 11/909711 |
Document ID | / |
Family ID | 37086779 |
Filed Date | 2009-06-11 |
United States Patent
Application |
20090147748 |
Kind Code |
A1 |
Ofuji; Yoshiaki ; et
al. |
June 11, 2009 |
TRANSMISSION APPARATUS, RECEPTION APPARATUS, MOBILE COMMUNICATIONS
SYSTEM AND TRANSMISSION CONTROL METHOD
Abstract
A disclosed transmission apparatus comprises a switching portion
that switches radio access methods; a frequency domain signal
generation portion that allocates a radio resource to a spread chip
sequence on which one of a fast Fourier transformation and a
series/parallel conversion is performed in accordance with the
switched radio accessed method, so as to generate a signal in a
frequency domain; and a transmission signal generation portion that
performs a fast inverse Fourier transformation on the signal in the
frequency domain so as to generate a transmission signal.
Inventors: |
Ofuji; Yoshiaki; (Kanagawa,
JP) ; Atarashi; Hiroyuki; (Kanagawa, JP) ;
Higuchi; Kenichi; (Kanagawa, JP) ; Sawahashi;
Mamoru; (Kanagawa, JP) |
Correspondence
Address: |
OSHA LIANG L.L.P.
TWO HOUSTON CENTER, 909 FANNIN, SUITE 3500
HOUSTON
TX
77010
US
|
Assignee: |
NTT DOCOMO, INC.
Tokyo
JP
|
Family ID: |
37086779 |
Appl. No.: |
11/909711 |
Filed: |
March 23, 2006 |
PCT Filed: |
March 23, 2006 |
PCT NO: |
PCT/JP2006/305835 |
371 Date: |
December 9, 2008 |
Current U.S.
Class: |
370/330 ;
375/135; 375/260; 375/E1.033 |
Current CPC
Class: |
H04L 5/0007 20130101;
H04L 27/2613 20130101; H04L 27/2636 20130101; H04W 72/0453
20130101; H04L 5/0051 20130101; H04L 27/0008 20130101; H04W 48/12
20130101; H04J 11/0026 20130101; H04L 5/006 20130101 |
Class at
Publication: |
370/330 ;
375/260; 375/135; 375/E01.033 |
International
Class: |
H04W 72/04 20090101
H04W072/04; H04L 27/28 20060101 H04L027/28; H04B 1/713 20060101
H04B001/713 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 31, 2005 |
JP |
2005-105492 |
Jun 14, 2005 |
JP |
2005-174394 |
Aug 23, 2005 |
JP |
2005-241899 |
Oct 31, 2005 |
JP |
2005-317567 |
Feb 8, 2006 |
JP |
2006-031749 |
Claims
1. A transmission apparatus usable in a communications system of a
single-carrier method and a communications system of a
multi-carrier system, the transmission apparatus comprising: a
switching portion that switches radio access methods; a frequency
domain signal generation portion that allocates a radio resource to
a spread chip sequence on which one of a fast Fourier
transformation and a series/parallel conversion is performed in
accordance with the switched radio accessed method, so as to
generate a signal in a frequency domain; and a transmission signal
generation portion that performs a fast inverse Fourier
transformation on the signal in the frequency domain so as to
generate a transmission signal.
2. The transmission apparatus as recited in claim 1, wherein the
switching portion switches the radio access methods in accordance
with information indicating the radio access method.
3. The transmission apparatus as recited in claim 1, wherein the
switching portion transmits a channel conditions measurement signal
using a predetermined frequency band requested to be allocated when
switching to the radio access method of the single-carrier
method.
4. The transmission apparatus as recited in claim 1, further
comprising a pilot signal generation portion that imparts
information indicating at least one of a requested frequency
bandwidth of a data channel, an amount of transmission data, and a
data rate, when switching to the radio access method of the
single-carrier method.
5. The transmission apparatus as recited in claim 4, wherein the
pilot signal generation portion imparts information indicating a
requested maximum transmission bandwidth of a pilot signal.
6. The transmission apparatus as recited in claim 5, wherein the
pilot signal generation portion transmits the pilot signal in
accordance with a frequency bandwidth and center frequency assigned
based on information indicating the requested maximum transmission
bandwidth of the pilot signal.
7. The transmission apparatus as recited in claim 6, wherein the
pilot signal generation portion transmits the pilot signal by a
frequency hopping method.
8. The transmission apparatus as recited in claim 7, wherein the
pilot signal generation portion transmits the pilot signal in each
assigned frequency bandwidth by the frequency hopping method.
9. The transmission apparatus as recited in claim 1, wherein the
frequency domain signal generation portion repeats a predetermined
number of times the spread chip sequence on which the fast Fourier
transformation is performed, and shifts each chip sequence repeated
the predetermined number of times so as to generate a predetermined
chip pattern.
10. The transmission apparatus as recited in claim 1, wherein the
frequency domain signal generation portion allocates the radio
resource depending on types of physical channels.
11. The transmission apparatus as recited in claim 10, wherein the
frequency domain signal generation portion allocates the radio
resource on a time-scale of transmission time interval length of a
frequency block when allocating the frequency block to the physical
channel.
12. The transmission apparatus as recited in claim 10, wherein the
frequency domain signal generation portion allocates the radio
resource so that at least a partial band of an allocated frequency
band when a signal to be transmitted is a contention-based
channel.
13. The transmission apparatus as recited in claim 10, wherein the
frequency domain signal generation portion allocates the radio
resource in accordance with a scheduling result when the signal to
be transmitted is assigned to a shared control channel.
14. The transmission apparatus as recited in claim 10, wherein the
frequency domain signal generation portion allocates the radio
resource in accordance with a scheduling result when the signal to
be transmitted is assigned to a shared data channel.
15. The transmission apparatus as recited in claim 14, wherein the
frequency domain signal generation portion allocates the radio
resource in accordance with a scheduling result in a time domain in
a frequency division multiplexing access method.
16. The transmission apparatus as recited in claim 15, wherein the
frequency domain signal generation portion allocates plural
frequency blocks in accordance with the data rate.
17. The transmission apparatus as recited in claim 14, wherein the
frequency domain signal generation portion allocates the radio
resource in accordance with a scheduling result in the time domain
and the frequency domain.
18. The transmission apparatus as recited in claim 17, wherein the
frequency domain signal generation portion groups frequency blocks
so as to perform allocation.
19. The transmission apparatus as recited in claim 14, wherein the
frequency domain signal generation portion changes an allocated
bandwidth in accordance with the data rate when the single-carrier
transmission is performed.
20. A reception apparatus comprising: a radio access method
determination portion that determines a radio access method used by
a transmission apparatus; and an imparting portion that imparts the
determined radio access method.
21. The reception apparatus as recited in claim 20, wherein the
radio access method determination portion determines the radio
access method in accordance with an environment where the reception
apparatus is installed.
22. The reception apparatus as recited in claim 20, wherein the
radio access method determination portion determines the radio
access method in accordance with a cell configuration.
23. The reception apparatus as recited in claim 20, wherein the
radio access method determination portion determines the radio
access method for each transmission apparatus.
24. The reception apparatus as recited in claim 20, wherein the
radio access method determination portion determines the radio
access method in accordance with a distance between the
transmission apparatus and the reception apparatus.
25. The reception apparatus as recited in claim 20, wherein the
radio access method determination portion determines the radio
access method in accordance with a transmission power in the
transmission apparatus.
26. The reception apparatus as recited in claim 20, further
comprising a radio resource allocation determination portion that
determines a frequency band to be allocated, in accordance with a
frequency band in which a channel conditions measurement signal is
transmitted, wherein the imparting portion transmits information
indicating the determined frequency band.
27. The reception apparatus as recited in claim 26, wherein the
radio resource allocation determination portion allocates a
frequency band within a range of a frequency band in which the
channel conditions measurement signal is transmitted.
28. The reception apparatus as recited in claim 27, wherein the
radio resource allocation determination portion determines the
transmission apparatus to which a frequency is to be allocated for
each frequency allocation unit determined in advance, in accordance
with at least one of reception power of the channel conditions
measurement signal in the reception apparatus, a type of data to be
transmitted by the transmission apparatus, transmission waiting
time, and a maximum transmission power of each mobile station.
29. The reception apparatus as recited in claim 26, wherein the
radio resource allocation determination portion allocates
continuous frequency bands to one transmission apparatus in
accordance with reception characteristic for each transmission
apparatus when the radio access method is determined to be the
single-carrier method.
30. The reception apparatus as recited in claim 20, further
comprising a pilot signal assignation portion that determines a
center frequency and transmission bandwidth of the pilot signal for
each transmission apparatus and transmits information indicating
the determined center frequency and transmission bandwidth of the
pilot signal to corresponding transmission apparatuses.
31. The reception apparatus as recited in claim 30, wherein the
pilot signal assignation portion imparts the determined center
frequency and transmission bandwidth of the pilot signal to the
corresponding transmission apparatuses by transmitting a frequency
block ID.
32. The reception apparatus as recited in claim 30, wherein the
pilot signal assignation portion determines the transmission
bandwidth in accordance with a maximum transmission power of each
transmission apparatus and a path-loss between each transmission
apparatus and the reception apparatus.
33. The reception apparatus as recited in claim 32, wherein the
pilot signal assignation portion determines to set the transmission
bandwidth to one of an integral multiple of and 2.sup.n times a
minimum transmission bandwidth determined in a system.
34. The reception apparatus as recited in claim 33, wherein the
pilot signal assignation portion determines that the transmission
bandwidth is a maximum bandwidth in which a received SINR expected
when the transmission apparatus transmits the pilot signal with a
maximum transmission power becomes a desired received SINR or
more.
35. The reception apparatus as recited in claim 33, wherein the
pilot signal assignation portion determines that the transmission
bandwidth is a minimum transmission bandwidth when a received SINR
expected when the transmission apparatus transmits the pilot signal
in a minimum transmission bandwidth becomes less than the desired
received SINR.
36. The reception apparatus as recited in claim 34, wherein the
pilot signal assignation portion calculates the expected received
SINR using an average path-loss between the reception apparatus and
the transmission apparatus and an average interference power in the
reception apparatus.
37. The reception apparatus as recited in claim 30, wherein the
pilot signal assignation portion determines the center frequency
and transmission bandwidth of the pilot signal in accordance with a
total up-link reception power.
38. The reception apparatus as recited in claim 37, wherein the
pilot signal assignation portion determines in advance a reference
value indicating deviation in the reception power of the pilot
signal in each transmission apparatus, and determines the center
frequency and transmission bandwidth of the pilot signal for each
transmission apparatus so that the deviation is the reference value
or below.
39. The reception apparatus as recited in claim 37, wherein the
pilot signal assignation portion allocates the transmission
bandwidth of the pilot signal so that the number of the
transmission apparatuses that transmit the pilot signals is
proportionate in each frequency band.
40. The reception apparatus as recited in claim 30, wherein the
pilot signal assignation portion determines the center frequency
and transmission bandwidth of the pilot signal for each
transmission apparatus in accordance with a remaining number of
repetition factor.
41. The reception apparatus as recited in claim 30, further
comprising: a reception characteristic measurement portion that
measures a reception characteristic of the pilot signal; and a
radio resource allocation determination portion that allocates the
frequency band within a range of the transmission band of the pilot
signal to each transmission apparatus in accordance with
information indicating the reception characteristic, the
transmission band of the pilot signal, and a requested frequency
bandwidth of a data channel.
42. The reception apparatus as recited in claim 41, wherein the
radio resource allocation determination portion allocates the
frequency band to each transmission apparatus in accordance with a
frequency allocation unit determined in advance.
43. The reception apparatus as recited in claim 41, wherein the
radio resource allocation determination portion uses a reception
characteristic measured in advance as the reception characteristic
of a band in which the pilot signal is not transmitted.
44. The reception apparatus as recited in claim 41, wherein the
reception characteristic measurement portion measures the reception
characteristic of the transmitted pilot signal using the frequency
allocation unit determined in advance as a measurement unit.
45. The reception apparatus as recited in claim 41, wherein the
reception characteristic measurement portion measures the reception
characteristic of the transmitted pilot signal using a requested
allocation band of the data channel as a measurement unit.
46. The reception apparatus as recited in claim 26, wherein the
radio resource allocation determination portion assigns an up-link
transmission power in accordance with the allocated frequency
bandwidth.
47. The reception apparatus as recited in claim 26, wherein the
radio resource allocation determination portion assigns a
transmission power in accordance with an interference power in a
band to be allocated so that a ratio of a requested radiowaves
power to the interference power becomes a predetermined power.
48. The reception apparatus as recited in claim 26, wherein the
radio resource allocation determination portion sets at least one
of a required quality for a data channel and a required quality for
the channel conditions measurement signal.
49. The reception apparatus as recited in claim 48, wherein the
radio resource allocation determination portion imparts at least
one of the required quality for the data channel and the required
quality for the channel conditions measurement signal through a
broadcast channel.
50. The reception apparatus as recited in claim 48, wherein the
radio resource allocation determination portion controls the
transmission power in accordance with the required quality for the
channel conditions measurement signal when no data channel is
allocated.
51. The reception apparatus as recited in claim 48, wherein the
radio resource allocation determination portion controls the
transmission power for a channel conditions measurement signal
portion and a data portion time-multiplexed in a transmission frame
in accordance with the required quality for the data channel, when
the data channel is allocated.
52. The reception apparatus as recited in claim 26, wherein the
radio resource allocation determination portion assigns the
transmission power so as to realize substantially a constant
transmission power density.
53. The reception apparatus as recited in claim 46, wherein when
the transmission apparatus to which the frequency band is allocated
transmits a signal in accordance with an assigned transmission
power and the reception power of the channel conditions measurement
signal, the radio resource allocation determination portion
determines use of one of the instantaneous value and the average
value of the reception power of the signal transmitted by the
transmission apparatus in the reception apparatus and the
interference power, and determines a modulation method and an error
correction code rate in accordance with a ratio of the determined
reception power to the determined interference power.
54. The reception apparatus as recited in claim 53, wherein the
radio resource allocation determination portion determines MCS in
accordance with the reception quality of the pilot signal measured
for each frequency allocation unit and imparts the determined MCS
to the transmission apparatus.
55. The reception apparatus as recited in claim 53, wherein the
radio resource allocation determination portion determines MCS in
accordance with the reception quality of the pilot signal in the
allocated frequency band and imparts the determined MCS to the
transmission apparatus.
56. The reception apparatus as recited in claim 46, wherein once
the radio resource allocation determination portion allocates a
frequency band to a transmission apparatus, the radio resource
allocation determination portion continues to allocate the
frequency band to the same transmission apparatus in a time-wise
manner until a reception power changes to exceed a threshold value
determined in advance, the transmission power being of the channel
conditions measurement signal of the transmission apparatus in the
allocated frequency band.
57. A mobile communications system including a reception apparatus
and a transmission apparatus usable in a communications system of a
single-carrier method and a communications system of a
multi-carrier system, the communications system comprising: a radio
access method determination portion that determines a radio access
method used by the transmission apparatus; an imparting portion
that imparts information indicating the determined radio access
method; a switching portion that switches radio access methods; a
frequency domain signal generation portion that allocates a radio
resource to a spread chip sequence on which one of a fast Fourier
transformation and a series/parallel conversion is performed in
accordance with the switched radio access method so as to generate
a signal in a frequency domain; and a transmission signal
generation portion that performs a fast inverse Fourier
transformation on the signal in the frequency domain so as to
generate a transmission signal.
58. A transmission control method comprising: a step in which a
reception apparatus determines a radio access method to be used; a
step in which the reception apparatus imparts information
indicating the determined radio access method; a step in which a
transmission apparatus receives information indicating the radio
access method; a step in which the transmission apparatus switches
radio access methods in accordance with the information indicating
the radio access method; a step in which the transmission apparatus
allocates a radio resource to a spread chip sequence on which one
of a fast Fourier transformation and a series/parallel conversion
performed is performed so as to generate a signal in a frequency
domain; and a step in which the transmission apparatus performs a
fast inverse Fourier transformation on the signal in the frequency
domain so as to generate a transmission signal.
59. The transmission control method as recited in claim 58, further
comprising a step in which the transmission apparatus transmits, to
the reception apparatus, information indicating at least one of a
requested frequency bandwidth of a data channel, a quantity of
transmission data, and a data rate.
60. The transmission control method as recited in claim 59, further
comprising a step in which the transmission apparatus transmits
information indicating a requested maximum transmission bandwidth
of the pilot signal.
61. The transmission control method as recited in claim 59, further
comprising a step in which the transmission apparatus transmits the
pilot signal in accordance with a frequency bandwidth and center
frequency assigned in accordance with the information indicating
the requested maximum transmission bandwidth of the pilot
signal.
62. The transmission apparatus as recited in claim 61, wherein the
pilot signal is transmitted by a frequency hopping method in the
step in which the transmission apparatus transmits the pilot
signal.
63. The transmission control method as recited in claim 58, wherein
the step in which the transmission apparatus allocates the radio
resource includes a step in which the spread chip sequence on which
the fast Fourier transformation is performed is repeated a
predetermined number of times; and a step in which each chip
sequence repeated the predetermined number of times are shifted so
as to generate a predetermined chip pattern.
64. The transmission control method as recited in claim 58, wherein
the step in which the transmission apparatus allocates the radio
resource includes a step in which the radio resource is allocated
in accordance with types of physical channels.
65. The transmission control method as recited in claim 64, wherein
the step in which the radio resource is allocated includes a step
in which the radio resource is allocated using a transmission time
interval of a frequency block as a unit when the frequency block is
allocated to the physical channel.
66. The transmission control method as recited in claim 64, wherein
the step in which the radio resource is allocated includes a step
in which the radio resource is allocated in accordance with a
scheduling result when a signal to be transmitted is assigned to a
shared data channel.
67. The transmission control method as recited in claim 66, wherein
the step in which the radio resource is allocated includes a step
in which the radio resource is allocated in accordance with a
scheduling result in a time domain in a frequency division
multiplexing access method.
68. The transmission control method as recited in claim 67, wherein
the step in which the radio resource is allocated includes a step
in which plural frequency blocks are allocated in accordance with a
data rate.
69. The transmission control method as recited in claim 64, wherein
the step in which the radio resource is allocated includes a step
in which the radio resource is allocated in accordance with a
scheduling result in the time domain and the frequency domain.
70. The transmission control method as recited in 64, wherein the
step in which the radio resource is allocated includes a step in
which frequency blocks are grouped and allocated.
71. The transmission control method as recited in claim 66, wherein
the step in which the radio resource is allocated includes a step
in which a bandwidth to be allocated is changed in accordance with
the data rate when a single-carrier transmission is performed.
72. The transmission control method as recited in claim 64, wherein
the step in which the radio resource is allocated includes a step
in which a frequency band is allocated within a range of the
frequency band in which a channel conditions measurement signal is
transmitted.
73. The transmission control method as recited in claim 72, wherein
the step in which the radio resource is allocated includes a step
in which there is determined a mobile station to which a frequency
is allocated for each frequency allocation unit in accordance with
at least one of a transmission power of the channel conditions
measurement signal in the transmission apparatus, types of data
that the mobile station is to transmit, a transmission waiting
time, and a maximum transmission power of each mobile station.
74. The transmission control method as recited in claim 72, wherein
the step in which the radio resource is allocated includes a step
in which continuous frequency bands are allocated to one mobile
station in accordance with a reception characteristic of each
mobile station when the radio access method is determined to be the
single-carrier method.
75. The transmission control method as recited in claim 58, further
comprising: a step in which the reception apparatus assigns a
center frequency and a transmission bandwidth of a pilot signal for
each transmission apparatus in accordance with information
indicating a requested maximum transmission bandwidth of the pilot
signal; and a step in which the reception apparatus transmits
information indicating the determined center frequency and
transmission bandwidth of the pilot signal to a corresponding
transmission apparatus.
76. The transmission control method as recited in claim 75, wherein
the information indicating the determined center frequency and the
transmission bandwidth is imparted to a corresponding transmission
apparatus by transmitting a frequency block ID in the step in which
the reception apparatus transmits the information.
77. The transmission control method as recited in claim 75, wherein
the transmission bandwidth is determined in accordance with a
maximum transmission power of each transmission apparatus and a
path-loss between each transmission apparatus and the reception
apparatus, in the step in which the reception apparatus assigns the
center frequency and the transmission bandwidth.
78. The transmission control method as recited in claim 77, wherein
the transmission bandwidth is determined to be one of an integral
multiple of and 2.sup.n times a minimum transmission bandwidth
determined in a system in the step in which the reception apparatus
assigns the center frequency and transmission bandwidth.
79. The transmission control method as recited in claim 78, wherein
the transmission bandwidth is determined to be a maximum bandwidth
in which a received SINR expected when the transmission apparatus
transmits the pilot signal with a maximum transmission power
becomes a required received SINR or more in the step in which the
reception apparatus assigns the center frequency and the
transmission bandwidth.
80. The transmission control method as recited in claim 78, wherein
the transmission bandwidth is determined to be a minimum bandwidth
when a received SINR expected when the transmission apparatus
transmits the pilot signal with a maximum transmission power
becomes less than a required received SINR in the step in which the
reception apparatus assigns the center frequency and the
transmission bandwidth.
81. The transmission control method as recited in claim 79, wherein
the expected received SINR is calculated using an average
interference power in the reception apparatus and an average
path-loss between the transmission apparatus and the reception
apparatus in the step in which the reception apparatus assigns the
center frequency and the transmission bandwidth.
82. The transmission control method as recited in claim 75, wherein
the center frequency and the transmission bandwidth of the pilot
signal are determined in accordance with a total up-link reception
power in the step in which the reception apparatus assigns the
center frequency and the transmission bandwidth.
83. The transmission control method as recited in claim 75, wherein
the center frequency and the transmission bandwidth of the pilot
signal are determined for each transmission apparatus in accordance
with a remaining number of repetition factors in the step in which
the reception apparatus assigns the center frequency and the
transmission bandwidth.
84. The transmission control method as recited in claim 75, further
comprising: a step in which the reception apparatus measures a
reception characteristic of the pilot signal; and a step in which
the reception apparatus allocates a frequency band within a range
of a transmission band of the pilot signal to each transmission
apparatus in accordance with information indicating the reception
characteristic, the transmission band of the pilot signal and a
requested frequency bandwidth.
85. The transmission control method as recited in claim 84, wherein
the frequency band is allocated to each transmission apparatus
based on a frequency allocation unit determined in advance in the
step in which the reception apparatus allocates the frequency
band.
86. The transmission control method as recited in claim 84, wherein
a reception characteristic measured in advance is used as the
reception characteristic for a band in which the pilot signal is
not transmitted in the step in which the reception apparatus
allocates the frequency band.
87. The transmission control method as recited in claim 84, wherein
the reception characteristic of the pilot signal is measured using
a frequency band allocation unit as a measurement unit in the step
in which the reception apparatus measures the reception
characteristic of the pilot signal.
88. The transmission control method as recited in claim 84, wherein
a reception characteristic of a transmitted pilot signal is
measured using a requested allocation band of the data channel as a
measurement unit in the step in which the reception apparatus
measures the reception characteristic of the pilot signal.
89. The transmission control method as recited in claim 65, further
comprising a step in which an up-link transmission power is
assigned in accordance with an allocated frequency bandwidth.
90. The transmission control method as recited in claim 89, wherein
the transmission power is assigned in accordance with interference
power in a band to be allocated so that a ratio of a requested
radiowaves power to an interference power becomes a predetermined
value in the step in which the up-link transmission power is
assigned.
91. The transmission control method as recited in claim 65, wherein
at least one of a required quality for a data channel and a
required quality for a channel conditions measurement signal is set
in the step in which the up-link transmission power is
assigned.
92. The transmission control method as recited in claim 91, wherein
at least one of the required quality for the data channel and the
required quality for the channel conditions measurement signal is
imparted through a broadcast channel in the step in which the
up-link transmission power is assigned.
93. The transmission control method as recited in claim 91 wherein
the transmission power is controlled in accordance with the
required quality for the channel conditions measurement signal when
no data channel is allocated in the step in which the up-link
transmission power is assigned.
94. The transmission control method as recited in claim 91, wherein
the transmission power is controlled for a channel conditions
measurement signal portion and a data portion time-multiplexed in a
transmission frame in accordance with the required quality for the
data channel in the step in which the up-link transmission power is
assigned when the data channel is allocated.
95. The transmission control method as recited in claim 89, wherein
the step in which the up-link transmission power is assigned
includes a step in which the transmission power is assigned so that
a transmission power density is substantially constant.
96. The transmission control method as recited in claim 89, further
comprising: a step in which when the transmission apparatus to
which the frequency band is allocated transmits a signal in
accordance with an assigned transmission power and a reception
power of the channel conditions measurement signal, use of one of
an instantaneous value and an average value of the reception power
of the signal transmitted by the transmission apparatus in the
reception apparatus and the interference power is determined; and a
step in which a modulation method and an error correction code rate
are determined in accordance with a ratio of the determined
reception power to an interference power.
97. The transmission control method as recited in claim 96, wherein
MCS is determined in accordance with a reception quality of the
pilot signal measured for each frequency allocation unit in the
step in which the modulation method and the error correction code
rate are determined.
98. The transmission control method as recited in claim 96, wherein
MCS is determined in accordance with a reception quality of the
pilot signal in an allocation band in the step in which the
modulation method and the error correction code rate are
determined.
99. The transmission control method as recited in claim 65, wherein
once a frequency band is allocated to a transmission apparatus, the
frequency band is continuously allocated to the same transmission
apparatus in a time-wise manner until a reception power changes to
exceed a threshold value determined in advance, the transmission
power being of a channel conditions measurement signal of the
transmission apparatus in the allocated frequency band, in the step
in which the radio resource is allocated.
Description
TECHNICAL FIELD
[0001] The present invention relates to a transmission apparatus, a
reception apparatus, a communications system and a transmission
control method.
BACKGROUND ART
[0002] A fourth generation (4G) mobile communications method which
is the next generation of IMT-2000 (International Mobile
Telecommunications 2000) is under development. The fourth
generation (4G) method is expected to flexibly support various
environments from a multi-cell environment including a cellular
system to an isolated cell environment such as a hotspot area and
an indoors area, and increase frequency utilization efficiencies in
both cell environments.
[0003] In the fourth generation communications method, the
following radio access methods have been proposed for a link from a
mobile station to a base station (referred to as an up-link,
hereinafter). As single-carrier transmission methods, a DS-CDMA
(Direct Sequence Code Division Multiple Access) method, an IFDMA
(Interleaved Frequency Division Multiple Access) method, and a
VSCRF-CDMA (Variable Spreading and Chip Repetition Factors-CDMA)
method have been proposed, for example. As multi-carrier methods,
an OFDM (Orthogonal Frequency Division Multiplexing) method, a
Spread OFDM method, an MC-CDMA (Multi-Carrier Code Division
Multiple Access) method, and a VSF-Spread OFDM (Variable Spreading
Factor Spread OFDM) method have been proposed.
[0004] The single-carrier method provides high power efficiency
because peak power is lower in terms of consumption power in a
terminal, which reduces back-off of a transmission power
amplifier.
[0005] As an example of the single-carrier methods, the VSCRF-CDMA
method is explained with reference to FIG. 1 (See patent-related
document 1).
[0006] A spreading portion 1 includes a code multiplication portion
2, a repetitive synthesis portion 8 connected to the code
multiplication portion 2, and a phase shift portion 10 connected to
the repetitive synthesis portion 8.
[0007] The code multiplication portion 2 multiplies a transmission
signal by a spreading code. For example, a multiplier 4 multiplies
the transmission signal by a channelization code defined under a
predetermined code spreading ratio SF. In addition, a multiplier 6
multiplies the transmission signal by a scramble code.
[0008] The repetitive synthesis portion 8 compresses the spread
transmission signal in a time-wise manner and performs chip
repetition a predetermined number of times (CRF times). The
transmission signal to which the repetition has been applied
presents a comb-shaped frequency spectrum. When the repetition
number CFR is equal to one, the repetitive synthesis portion 8 has
the same configuration and operations in the usual DS-CDMA
method.
[0009] The phase shift portion 10 deviates (or shifts) a phase of
the transmission signal by a predetermined frequency established
specifically for each mobile station.
[0010] In the VSCRF-CDMA method, when the CRF is greater than 1,
for example, equal to 4, a comb-shaped frequency spectrum utilized
by each user is arranged in a distributed manner over the entire
band, as shown in FIG. 2A. In this case, a user-specific frequency
offset is smaller than an allocated bandwidth.
[0011] On the other hand, when CRF is equal to 1, the spectrum
utilized by each user is arranged over a block, as shown in FIG.
2B. In this case, the user-specific frequency offset is greater
than the allocated bandwidth.
[0012] In addition, there has been proposed a radio access method
where a comb-shaped frequency spectrum in the frequency domain is
obtained (See non-patent documents 1, 2).
[0013] A transmission apparatus 30 to which the radio access method
is applied includes a FFT portion 12 to which a spread data
sequence is input, a rate conversion portion 14 connected to the
FFT portion 12, a frequency domain signal generation portion 16
connected to the rate conversion portion 14, an IFFT portion 18
connected to the frequency domain signal generation portion 16, a
GI addition portion 20 connected to the IFFT portion 18, and a
filter 22 connected to the GI addition portion 20, as shown in FIG.
3.
[0014] The fast Fourier transformation (FFT) portion 12 divides the
spread data sequence every Q chips into blocks and performs a fast
Fourier transformation, thereby transforming the blocks into the
frequency domain. As a result, Q single-carrier signals are
obtained in the frequency domain. By the way, the spread data
sequence corresponds to an output signal of the multiplier 6 in the
spreading portion 1 explained with reference to FIG. 1.
[0015] The rate conversion portion 14 repeats a predetermined
number of times, for example, CRF times the Q counts of the
single-carrier signals. As a result, the number of the
single-carrier signals generated is N.sub.sub=Q.times.CRF.
[0016] The frequency domain signal generation portion 16 shifts
each single-carrier signal on the frequency axis so that the
spectrum becomes comb-shaped. For example, when a process
corresponding to CRF=4 is carried out, three zeros are arranged
between every single-carrier signal. As a result, the comb-shaped
frequency spectra explained with reference to FIGS. 2A and 2B are
formed.
[0017] The IFFT portion 18 performs a fast inverse Fourier
transformation on the comb-shaped spectra obtained by shifting each
single-carrier signal on the frequency axis.
[0018] The guard interval addition portion 20 adds guard intervals
to a signal to be transmitted. The guard intervals are obtained by
replicating a portion of the top or end of a symbol to be
transmitted. The filter 22 performs a band limitation on the
transmission signal.
[0019] On the other hand, the multi-carrier method, which has a
long symbol, can provide an improved reception quality in a multi
path environment by providing the guard intervals.
[0020] As an example, the OFDM method is explained with reference
to FIG. 4.
[0021] FIG. 4 is a block diagram of a transmission portion used in
a transmission apparatus of the OFDM method.
[0022] The transmission portion 40 includes a series/parallel (S/P)
conversion portion 32, a sub carrier mapping portion 34 connected
to the S/P conversion portion 32, an IFFT portion 36 connected to
the sub carrier mapping portion 34, and a GI addition portion 38
connected to the IFFT portion 36.
[0023] The series/parallel conversion portion (S/P) 32 converts
series signal sequences to parallel signal sequences.
[0024] The sub carrier mapping portion 34 allocates to each sub
carrier each signal which is converted to the parallel signal
sequence in the series/parallel conversion portion 32. For example,
the sub carrier mapping portion 34 allocates discrete sub carriers
to each user as shown in FIG. 5A in order to obtain a frequency
diversity effect. In addition, the sub carrier mapping portion 34
allocates consecutive sub carriers to each user as shown in FIG.
5B.
[0025] The fast inverse Fourier (IFFT) portion 36 performs the fast
inverse Fourier transformation on the input signal so as to perform
modulation of the OFDM method.
[0026] The guard interval addition portion 38 adds guard intervals
to a signal to be transmitted and generates a symbol of the OFDM
method.
[0027] Patent-related Publication 1: Japanese Patent Application
Laid-Open Publication No. 2004-297756.
[0028] Non-patent Publication 1: M.Schnell, I. Broeck, and U.
Sorger, "A promising new wideband multiple-access scheme for future
mobile communication," European Trans. on Telecommun. (ETT), vol.
10, no. 4, pp. 417-427, July/August 1999.
[0029] Non-patent Publication 2: R. Dinis, D. Falconer, C. T. Lam,
and M. Sabbaghian, "A Multiple Access Scheme for the Uplink of
Broadband Wireless Systems," in Proc. Globecom 2004, December
2004.
DISLOSURE OF INVENTION
Problem to be Solved by the Invention
[0030] However, the aforementioned related art has the following
drawbacks.
[0031] The single-carrier method is accompanied with degradation of
reception quality due to multi-pass interference especially when
signals are transmitted at higher speed since symbols used are
short.
[0032] In addition, the multi-carrier method, which requires a
larger back-off since peak power becomes high regarding a terminal
consumption power, is accompanied by a problem of lower power
efficiency.
[0033] The present invention is directed to providing a
transmission apparatus, a reception apparatus, a mobile
communications system, and a transmission method where the
single-carrier radio access method and the multi-carrier radio
access method are switchable.
Means for Solving the Problem
[0034] In order to solve the above disadvantages, a transmission
apparatus usable in a communications system of a single-carrier
method and a communications system of a multi-carrier system,
according to an embodiment of the present invention, comprises a
switching portion that switches radio access methods, a frequency
domain signal generation portion that allocates a radio resource to
a spread chip sequence on which one of a fast Fourier
transformation and a series/parallel conversion is performed in
accordance with the switched radio accessed method, so as to
generate a signal in a frequency domain; and a transmission signal
generation portion that performs a fast inverse Fourier
transformation on the signal in the frequency domain so as to
generate a transmission signal.
[0035] With such a configuration, the single-carrier-based
communications method and the multi-carrier-based communications
method are realized in a common module and communications are
performed by both access methods.
[0036] In addition, a reception apparatus according to an
embodiment of the present invention comprises a radio access method
determination portion that determines a radio access method used by
a transmission apparatus; and an imparting portion that imparts the
determined radio access method.
[0037] With such a configuration, the radio access method used by
the transmission apparatus is determined and imparted.
[0038] Moreover, a mobile communications system including a
reception apparatus and a transmission apparatus usable in a
communications system of a single-carrier method and a
communications system of a multi-carrier system, according to an
embodiment of the present invention comprises: a radio access
method determination portion that determines a radio access method
used by the transmission apparatus; an imparting portion that
imparts information indicating the determined radio access method;
a switching portion that switches radio access methods; a frequency
domain signal generation portion that allocates a radio resource to
a spread chip sequence on which one of a fast Fourier
transformation and a series/parallel conversion is performed in
accordance with the switched radio access method so as to generate
a signal in a frequency domain; and a transmission signal
generation portion that performs a fast inverse Fourier
transformation on the signal in the frequency domain so as to
generate a transmission signal.
[0039] With such a configuration, the single-carrier-based
communications method and the multi-carrier-based communications
method are realized in a common module and communications are
performed by both access methods.
[0040] Furthermore, a transmission control method according to an
embodiment of the present invention comprises a step in which a
reception apparatus determines a radio access method to be used; a
step in which the reception apparatus imparts information
indicating the determined radio access method; a step in which a
transmission apparatus receives information indicating the radio
access method; a step in which the transmission apparatus switches
radio access methods in accordance with the information indicating
the radio access method; a step in which the transmission apparatus
allocates a radio resource to a spread chip sequence on which one
of a fast Fourier transformation and a series/parallel conversion
is performed so as to generate a signal in a frequency domain; and
a step in which the transmission apparatus performs a fast inverse
Fourier transformation on the signal in the frequency domain so as
to generate a transmission signal.
[0041] With such a method, communications are made by the
single-carrier-based communications method and the
multi-carrier-based communications method in accordance with the
determined radio access method.
Advantage of the Invention
[0042] According to embodiments of the present invention, a
transmission apparatus, a reception apparatus, a mobile
communications system, and a transmission method where the
single-carrier radio access method and the multi-carrier radio
access method are provided are switchable.
BRIEF DESCRIPTION OF DRAWINGS
[0043] FIG. 1 is a block diagram indicating a spreading portion
used in a VACRF-CDMA-based transmission apparatus;
[0044] FIG. 2A illustrates an example of a frequency spectrum of a
transmission signal of a mobile station;
[0045] FIG. 2B illustrates an example of a frequency spectrum of a
transmission signal of a mobile station;
[0046] FIG. 3 is a block diagram illustrating a transmission
apparatus that performs a single-carrier transmission;
[0047] FIG. 4 is a block diagram illustrating a transmission
apparatus that performs a single-carrier transmission;
[0048] FIG. 5A illustrates an example of a frequency spectrum of a
transmission signal of a mobile station;
[0049] FIG. 5B illustrates another example of a frequency spectrum
of a transmission signal of a mobile station;
[0050] FIG. 6A is an explanatory view illustrating a cellular
environment;
[0051] FIG. 6B is an explanatory view illustrating a local area
environment;
[0052] FIG. 7 is a partial block diagram illustrating a
transmission apparatus according to one example of the present
invention;
[0053] FIG. 8 is an explanatory view illustrating switching between
a single-carrier method and a multi-carrier method;
[0054] FIG. 9 is an explanatory view illustrating switching between
a single-carrier method and a multi-carrier method;
[0055] FIG. 10 is an explanatory view illustrating switching
between a single-carrier method and a multi-carrier method;
[0056] FIG. 11 is an explanatory view illustrating a method of
transmitting up-link channel conditions;
[0057] FIG. 12A is an explanatory view illustrating notification of
a requested maximum transmission bandwidth of a data channel and a
pilot signal;
[0058] FIG. 12B is an explanatory view illustrating an expected
received SINR of a channel conditions measurement signal when
transmission is made at the maximum transmission power;
[0059] FIG. 12C is an explanatory view illustrating transmission
power control when no data channel is allocated and only a channel
conditions measurement signal is transmitted;
[0060] FIG. 12D is an explanatory view illustrating transmission
power control when a data channel is allocated;
[0061] FIG. 12E is an explanatory view illustrating one example of
transmission power control of a channel conditions measurement
signal when a data channel is allocated;
[0062] FIG. 12F is an explanatory view illustrating one example of
transmission power control of a channel conditions measurement
signal when a data channel is allocated;
[0063] FIG. 13 is an explanatory view illustrating shared channel
data channel scheduling;
[0064] FIG. 14 is an explanatory view illustrating shared channel
data channel scheduling;
[0065] FIG. 15 is an explanatory view illustrating interference
from other mobile stations;
[0066] FIG. 16A is an explanatory view illustrating interference
power fluctuations;
[0067] FIG. 16B is an explanatory view illustrating interference
power fluctuations;
[0068] FIG. 17 is an explanatory view illustrating shared channel
data channel scheduling;
[0069] FIG. 18 is an explanatory view illustrating shared channel
data channel scheduling;
[0070] FIG. 19A is an explanatory view illustrating shared channel
data channel scheduling;
[0071] FIG. 19B is an explanatory view illustrating shared channel
data channel scheduling;
[0072] FIG. 20A is an explanatory view illustrating radio resource
allocation in a transmission apparatus according to an example of
the present invention;
[0073] FIG. 20B is an explanatory view illustrating radio resource
allocation in a transmission apparatus according to an example of
the present invention;
[0074] FIG. 20C is an explanatory view illustrating radio resource
allocation in a transmission apparatus according to an example of
the present invention;
[0075] FIG. 21 is a partial block diagram illustrating a reception
apparatus according to an example of the present invention;
[0076] FIG. 22 is a partial block diagram illustrating a reception
apparatus according to an example of the present invention;
[0077] FIG. 23A is an explanatory view illustrating received SINR
measurement of a pilot signal transmitted by each mobile station,
in a reception apparatus according to an example of the present
invention;
[0078] FIG. 23B is an explanatory view illustrating received SINR
measurement of a pilot signal transmitted by each mobile station,
in a reception apparatus according to an example of the present
invention;
[0079] FIG. 24A is an explanatory view illustrating frequency
allocation for data channel transmission to a mobile station, in a
reception apparatus according to an example of the present
invention;
[0080] FIG. 24B is an explanatory view illustrating frequency
allocation for data channel transmission to a mobile station, in a
reception apparatus according to an example of the present
invention;
[0081] FIG. 25A is an explanatory view illustrating frequency
allocation for data channel transmission to a mobile station, in a
reception apparatus according to an example of the present
invention;
[0082] FIG. 25B is an explanatory view illustrating frequency
allocation for data channel transmission to a mobile station, in a
reception apparatus according to an example of the present
invention;
[0083] FIG. 25C is an explanatory view illustrating frequency
allocation for data channel transmission to a mobile station, in a
reception apparatus according to an example of the present
invention;
[0084] FIG. 26 is an explanatory view illustrating re-allocation of
a frequency band;
[0085] FIG. 27A is an explanatory view illustrating transmission
power determination;
[0086] FIG. 27B is an explanatory view illustrating transmission
power determination;
[0087] FIG. 28A is an explanatory view illustrating transmission
power determination;
[0088] FIG. 28B is an explanatory view illustrating transmission
power determination;
[0089] FIG. 29 is an explanatory view illustrating MCS assignment
at the time of data channel transmission to a mobile station that
is allowed to perform transmission;
[0090] FIG. 30 is a partial block diagram illustrating a reception
apparatus according to an example of the present invention;
[0091] FIG. 31 is an explanatory view illustrating assignment of a
bandwidth and center frequency of a pilot signal of each mobile
station, in a reception apparatus according to an example of the
present invention;
[0092] FIG. 32 is an explanatory view illustrating assignment of a
bandwidth and center frequency of a pilot signal of each mobile
station, in a reception apparatus according to an example of the
present invention;
[0093] FIG. 33A is an explanatory view illustrating assignment of a
bandwidth and center frequency of a pilot signal of each mobile
station, in a reception apparatus according to an example of the
present invention;
[0094] FIG. 33B is an explanatory view illustrating assignment of a
bandwidth and center frequency of a pilot signal of each mobile
station, in a reception apparatus according to an example of the
present invention;
[0095] FIG. 34 is an explanatory view illustrating received SINR of
a pilot signal transmitted from each mobile station, in a reception
apparatus according to an example of the present invention;
[0096] FIG. 35 is an explanatory view illustrating MCS allocation
at the time of data channel transmission to a mobile station that
is allowed to perform transmission, in a reception apparatus
according to an example of the present invention;
[0097] FIG. 36 is a flowchart illustrating operations of a
transmission apparatus according to an example of the present
invention;
[0098] FIG. 37 is a flowchart illustrating operations of a
reception apparatus according to an example of the present
invention; and
[0099] FIG. 38 is a flowchart illustrating operations of a mobile
communications system according to an example of the present
invention.
LIST OF REFERENCE SYMBOLS
[0100] 1: spreading portion [0101] 2: code multiplication portion.
[0102] 3: phase shift portion [0103] 30, 40, 100: transmission
apparatus [0104] 200, 200.sub.1, 200.sub.2, 200.sub.3, 200.sub.4,
200.sub.5, 200.sub.6: base station [0105] 300: mobile station
[0106] 400: reception apparatus
BEST MODE FOR CARRYING OUT THE INVENTION
[0107] Referring to the accompanying drawings, a best mode for
carrying out the invention will be described based on the following
examples.
[0108] By the way, in all the drawings for describing the examples,
like reference marks are given to members or components having like
functions and unnecessary repetition of the description is
omitted.
[0109] A mobile communications system according to an example of
the present invention includes a mobile station and a base station
capable of radio-communicating with the mobile station.
[0110] A transmission apparatus according to an example of the
present invention is described.
[0111] The transmission apparatus is provided, for example, in the
mobile station and transmits through an up-link channel.
[0112] The transmission apparatus according to this example is used
in a cellular environment and a local area environment.
[0113] As shown in FIG. 6A, the cellular environment includes base
stations that cover cells (sectors), for example, base stations
200.sub.1, 200.sub.2, 200.sub.3, 200.sub.4, and 200.sub.5, and a
mobile station 300 capable of radio-communicating with the base
station 200.sub.1. The cellular environment has a larger cell
radius and a higher transmission power of the mobile station than
the local area environment. However, a feasible data rate is lower
in the cellular environment due to interference from neighboring
cells.
[0114] Therefore, the single-carrier method is more advantageous
than the multi-carrier method as a up-link radio access method in
the cellular environment.
[0115] On the other hand, the local area environment such as an
indoor environment or a hotspot environment includes a base station
that covers a cell (sector), for example, a base station 200.sub.6
and a mobile station 300 capable of radio-communicating with the
base station 200.sub.6. The local area environment has a smaller
cell radius and a lower consumption power of the mobile station
than the cellular environment. However, the feasible data rate is
relatively higher in the local area environment.
[0116] Therefore, the multi-carrier method is more advantageous
than the single-carrier method as the up-link radio access method
in the local area environment.
[0117] Next, referring to FIG. 7, the transmission apparatus
according to this example is described.
[0118] A transmission apparatus 100 includes a spreading and
channel code portion 102 to which symbol sequences are input, a
switching portion 106 connected to the spreading and channel code
portion 102, a fast Fourier transformation (FFT) portion 108 and a
series/parallel (S/P) conversion portion 110 connected to the
switching portion 106, and a rate conversion portion 112 connected
to the FFT portion 108 and the S/P conversion portion 110.
[0119] In addition, the transmission apparatus 100 according to
this example includes a frequency domain signal generation portion
114 connected to the rate conversion portion 112, a fast inverse
Fourier transformation (IFFT) portion 116 connected to the
frequency domain signal generation portion 114, a guard interval
(GI) addition portion 118 connected to the IFFT portion 116, and a
filter 120 connected to the GI addition portion 118.
[0120] Moreover, the transmission portion 100 according to this
example includes a data modulation/spreading rate/channel coding
control portion 104 connected to the spreading and channel code
portion 102 and the frequency domain signal generation portion 114,
and a radio resource allocation control portion 122 connected to
the frequency domain signal generation portion 114. The switching
portion 106 is connected to the filter 120.
[0121] To the data modulation/spreading rate/channel coding control
portion 104 is input MCS (Modulation and Coding Scheme) information
for each user. To the radio resource allocation control portion 122
is input notification information indicating radio resource
allocation to each physical channel and information indicating a
scheduling result for each user.
[0122] The data modulation/spreading rate/channel coding control
portion 104 determines a spreading rate of orthogonal codes
employed in the spreading and channel code portion 102 and outputs
the orthogonal codes of the determined spreading rate and a
cell-specific scramble code as well as the input MCS information
for each user to the spreading and channel code portion 102.
[0123] For example, in the cellular environment, the data
modulation/spreading rate/channel coding control portion 104
determines an orthogonal code of a spreading rate corresponding to
the cellular environment and the cell-specific scramble code. On
the other hand, in a local area environment, the data
modulation/spreading rate/channel coding control portion 104
determines an orthogonal code of a spreading rate corresponding to
the local area environment and the cell-specific scramble code. In
addition, the data modulation/spreading rate/channel coding control
portion 104 outputs the number of sub carrier sets to the frequency
domain signal generation portion 114.
[0124] The spreading and channel code portion 102 performs channel
coding by applying an error correction code such as a turbo code or
a convolution code to the input binary information sequence in
accordance with the input MCS information, and thus modulates the
channel-coded data. In addition, the spreading and channel code
portion 102 generates a spread chip sequence by performing a
spreading process using the input orthogonal codes of the spreading
rate and the cell-specific scramble code, and thus outputs the
spread chip sequence to the switching portion 106.
[0125] The switching portion 106 determines whether the
information, which is provided by the base station 200 and
indicates the radio access methods, shows the single-carrier method
or the multi-carrier method. When the switching portion 106
determines that the imparted information indicating the radio
access method shows the single-carrier method, the switching
portion 106 outputs the input spread chip sequence to the FFT
portion 108. When the switching portion 106 determines that the
imparted information indicating the radio access method shows the
multi-carrier method, the switching portion 106 determines that the
imparted information indicating the radio access method shows the
multi-carrier method, the switching portion 106 outputs the input
spread chip sequence to the S/P conversion portion 110. In
addition, the switching portion 106 outputs the imparted
information indicating the radio access method to the filter
120.
[0126] For example, the switching portion 106 determines a radio
access method in accordance with the notification information from
the base station 200. In this case, the base station 200 determines
in a radio access method determination portion 402 (described
later) whether the single-carrier method or the multi-carrier
method is allowed to be used by each user (mobile station), and
imparts control information indicating the determined radio access
method to the mobile stations 300 as shown in FIG. 8.
[0127] In addition, the switching portion 106 may determine the
single-carrier method or the multi-carrier method in accordance
with the radio access method determined for each cell, for example.
In this case, the radio access method determination portion 402 of
the reception apparatus provided in the base station 200 steadily
determines in advance the up-link radio access method for each base
station in accordance with the cell configuration.
[0128] For example, when the base station 200 is installed, the
radio access method determination portion 402 determines the radio
access method used in accordance with the cell configuration, for
example, a cell radius, the presence or the absence of neighboring
cells, or the like. For example, the single-carrier method is used
when the cell radius is large, whereas the multi-carrier method is
used when the cell radius is small. The radio access method
determination portion 402 imparts information indicating the
determined access method, as common control information for all the
users, to the mobile stations 300, as shown in FIG. 9.
[0129] According to the above, the radio access method is
determined when the base station is installed, which leads to
simplified configuration and control.
[0130] In addition, the switching portion 106 may determine the
single-carrier method or the multi-carrier method in accordance
with the radio access method determined for each user (mobile
station), for example. In this case, the access methods may be
switched in accordance with the distance between each user and the
base station, or the transmission power margin in each user.
[0131] For example, when the access methods are switched in
accordance with the distance between each user and the base station
200, the path-loss may be used, for example, as a quantity
corresponding to the distance between a user and the base station
200. In this case, the mobile station 300 measures the path-loss in
a down-link using the reception power of the down-link pilot
signal, and thus reports information indicating the measured
path-loss to the base station 200 through the up-link.
[0132] The radio access method determination portion 402 of the
reception apparatus provided in the base station 200 determines
that the distance between the base station 200 and the mobile
station 300 is large when the received path-loss value is greater
than a predetermined threshold, and determines use of a
single-carrier method. Then, the radio access method determination
portion 402 imparts the use of a single-carrier method to the
mobile stations 300 as common control information dedicated to a
user, as shown in FIG. 10.
[0133] The radio access method determination portion 402 of the
reception apparatus provided in the base station 200 determines
that the distance between the base station 200 and the mobile
station 300 is small when the received path-loss value is smaller
than a predetermined threshold, and determines use of a
single-carrier method. Then, the radio access method determination
portion 402 imparts the use of a single-carrier method to the
mobile stations 300 as common control information dedicated to a
user, as shown in FIG. 10.
[0134] In such a manner, the radio access methods are controlled
for each mobile station in accordance with the distance between the
base station and the corresponding mobile station.
[0135] In addition, the mobile stations may determine the use of
the single-carrier method or the multi-carrier method in accordance
with the measured path-loss and report the determined result to the
base station 200.
[0136] In addition, when the access methods are switched in
accordance with the transmission power margin in each user, "(the
maximum allowance transmission power)-(the current transmission
power)" may be used, for example, as an indicator of the
transmission power margin in each user. In this case, each of the
mobile stations reports a value indicating "(the maximum allowance
transmission power)-(the current transmission power)" to the base
station.
[0137] The radio access method determination portion 402 of the
reception apparatus provided in the base station 200 determines
that the margin in the transmission power is small when the value
indicating "(the maximum allowance transmission power)-(the current
transmission power)" is smaller than a predetermined threshold, and
determines the use of the single-carrier method. Thus, the radio
access method determination portion 402 imparts the information to
the mobile stations 300, as shown in FIG. 10.
[0138] On the other hand, the radio access method determination
portion 402 of the reception apparatus provided in the base station
200 determines that the transmission power margin is large when the
value indicating "(the maximum allowance transmission power) (the
current transmission power)" is greater than a predetermined
threshold, and determines use of the multi-carrier method. Then,
the radio access method determination portion 402 imparts the use
of the multi-carrier method to the mobile stations 300, as shown in
FIG. 10.
[0139] According to the above, the access methods are controlled in
accordance with the performance of each mobile station.
[0140] In addition, the mobile stations 300 may transmit
information indicating the maximum allowance transmission power and
information indicating the current transmission power. Then, the
radio access method determination portion 402 of the reception
apparatus provided in the base station 200 may calculate "the
maximum allowance transmission power--the current transmission
power" and control the radio access methods in accordance with the
calculated value.
[0141] Moreover, the mobile stations may determine use of the
single-carrier method or the multi-carrier method in accordance
with the transmission power margin and thus report the determined
result to the base station 200.
[0142] Furthermore, the switching portion 106 may transmit a
channel conditions measurement signal, for example, a pilot signal,
using a predetermined frequency band requested to be allocated, in
accordance with the radio access method determined for each user
(mobile station) as shown in FIG. 11. For example, the switching
portion 106 transmits the channel conditions measurement signal
using only an assigned frequency band among the frequency bands
allocated to the system. Specifically, when the frequency band of,
for example, 20 MHz is allocated for the system, the mobile
stations (transmission apparatus) are categorized into classes of
the mobile stations that can use 20 MHz, 10 MHz, and 5 MHz. In this
case, the switching portion 106 transmits the channel conditions
measurement signal using only the frequency band corresponding to a
class of the mobile stations (transmission apparatus) in accordance
with the radio access method determined for the user (mobile
station).
[0143] A radio resource allocation determination portion 404 of the
reception apparatus 400 allocates a frequency band to the mobile
station (transmission apparatus) to which the channel conditions
measurement signal is transmitted, in accordance with the frequency
band used to transmit the channel conditions measurement
signal.
[0144] Namely, each mobile station. (transmission apparatus)
transmits the pilot signal, and the base station (reception
apparatus) measures the pilot signals and thus the channel
conditions between the base station and the mobile stations,
thereby performing allocation of the frequency bands. The mobile
stations do not have to transmit the pilot signals using the entire
frequency band allocated to the system. But the mobile stations may
transmit the pilot signals using the predetermined bands. The base
station receives the pilot signal from each user and allocates the
frequency bands if there is a band to be allocated in the range of
the frequency bands. Then, the base station transmits the
information indicating the determined frequency bands to the
transmission apparatus.
[0145] In addition, the reception apparatus 400 may determine in
the radio access method determination portion 402 the frequency
bands for use in transmitting the channel conditions measurement
signal and thus transmit the information indicating the frequency
bands.
[0146] In addition, the switching portion 106 may include a pilot
signal generation portion, which transmits to the base station at
least one of information indicating a requested (maximum)
transmission bandwidth of a data channel, information indicating a
quantity of data to be transmitted, and information indicating a
data rate, in accordance with the access method determined for each
user (mobile station) when the determined radio access method is
the single-carrier method. Additionally, the pilot signal
generation portion may transmit information indicating a requested
(maximum) transmission bandwidth of the pilot signal to the base
station.
[0147] For example, the pilot signal generation portion transmits
to the base station at least one of information indicating the
requested (maximum) transmission bandwidth of the pilot signal,
information indicating the requested (maximum) transmission
bandwidth of the data channel, information indicating the quantity
of the data to be transmitted, and information indicating the data
rate, through a contention-based channel. For example, the maximum
transmission bandwidth is 5 MHz and the requested transmission
bandwidth is narrower than 5 MHz.
[0148] As shown in FIG. 12A, it is assumed that W_able is the
maximum bandwidth that can be used by the mobile station; Wp_req is
the requested maximum transmission bandwidth of the pilot signal;
and Wd_req is the requested (maximum) transmission bandwidth of the
data channel. The pilot signal generation portion determines Wd_req
within a range of Wd_req=<W.sub.able in accordance with the
quantity of data to be transmitted and the data rate. In addition,
the pilot signal generation portion determines Wp_req within a
range of Wd_req=<Wp_req=<W.sub.able.
[0149] The switching portion 106 may determine that the
transmission bandwidth of the channel conditions measurement signal
is an integral multiple of the minimum transmission bandwidth
determined in the system or 2.sup.n times the minimum transmission
bandwidth determined in the system.
[0150] In this case, the switching portion 106 performs
transmission using a maximum transmission bandwidth where a
received SINR expected when transmitting with the maximum
transmission power or "the maximum transmission power--delta P" can
exceed a required received SINR. For example, the switching portion
106 calculates the expected received SINR in accordance with an
average interference power in the base station and an average
path-loss between the base station (reception apparatus) and the
mobile station (transmission apparatus).
[0151] For example, when the maximum transmission bandwidth is 5
MHz and the minimum transmission bandwidth is 1.25 MHz as shown in
FIG. 12B, a transmission bandwidth that satisfies the required
received SINR of the channel conditions measurement signal is 1.25
MHz and 2.5 MHz among the transmission bandwidths, namely, 1.25
MHz, 2.5 MHz, and 3.75 MHz. Therefore, the maximum transmission
bandwidth that can exceed the required received SINR is 2.5
MHz.
[0152] In this case, even when the required received SINR is not
expected to be realized in the case of transmission using the
minimum transmission bandwidth, the transmission bandwidth used
does not become narrower than the minimum transmission bandwidth
and transmission is performed using the minimum transmission
bandwidth.
[0153] The required received SINR of the channel conditions
measurement signal is imparted through the broadcast channel
throughout the cell.
[0154] Moreover, the switching portion 106 may set a different
required quality for the channel conditions measurement signal,
separately from the required quality for the data channel, for
example, the required received SINR.
[0155] In this case, each required quality is imparted from a base
station apparatus through the broadcast channel to the mobile
stations administered by a sector concerned For example, the base
station apparatus imparts the required quality for the data channel
using a dedicated control channel.
[0156] The switching portion 106 performs transmission power
control based on the required quality for the channel conditions
measurement signal when no data channel is allocated and only the
channel conditions measurement signal is transmitted. For example,
the switching portion 106 performs transmission with a transmission
power determined by the transmission power control in accordance
with the required quality when transmitting the pilot signal. For
example, the switching portion 106 sets a low required quality
necessary and sufficient for the measurement of the channel
conditions, as shown in FIG. 12C. With this, interference by the
pilot signals is reduced, thereby improving the throughput as a
whole.
[0157] The switching portion 106 performs the transmission power
control for both a data portion and the channel conditions
measurement signal portion in accordance with the required quality
for the data channel when the data channel is allocated. For
example, the switching portion 106 performs transmission with the
same power as the data portion when the data channel is allocated,
as shown in FIG. 12D. In this case, a higher required quality is
set for the data portion since a highly efficient modulation method
and/or coding rate is used. The switching portion 106 transmits the
pilot signal with a higher transmission power since a highly
accurate channel estimation is required.
[0158] Specifically, when the data channel is allocated and an
allocation bandwidth for the data channel is narrower than the
transmission bandwidth for the channel conditions measurement
signal, the switching portion 106 controls the transmission power
of the channel conditions measurement signal to be a transmission
power that satisfies the required quality of the data channel, for
example, the required received SINR in the transmission bandwidth
for the channel conditions measurement signal, as shown in 12E.
[0159] When there is not a sufficient margin in the transmission
power and the required quality is not satisfied, the switching
portion 106 adjusts the transmission power to the maximum, as shown
in FIG. 12F.
[0160] The base station 200 determines a center frequency and a
transmission frequency bandwidth (transmission bandwidth) of the
pilot signal transmitted by the mobile station in accordance with
the information transmitted by the mobile station, for example, the
requested (maximum) transmission bandwidth of the pilot signal, and
thus imparts information indicating the determined center frequency
and information indicating the determined transmission bandwidth of
the pilot signal to the mobile stations.
[0161] The pilot signal generation portion transmits the pilot
signal in accordance with the imparted information indicating
center frequency and the imparted information indicating the
transmission bandwidth of the pilot signal. In addition, when a
frequency block ID is imparted, the pilot signal generation portion
transmits the pilot signal in accordance with the transmission
bandwidth and center frequency designated by the imparted frequency
block ID. In this case, the pilot signal generation portion may
transmit the pilot signal by a frequency hopping method. Moreover,
the pilot signal generation portion may transmit the pilot signal
through the frequency hopping by changing bands for use in
transmission for each assigned band.
[0162] The FFT portion 108 divides the spread data sequence every Q
chips into blocks, performs the fast Fourier transformation so as
to transform the divided sequence into the frequency domain, and
outputs the transformed divided sequence to the rate conversion
portion 112. As a result, the Q counts of the single-carrier
signals are obtained in the frequency domain.
[0163] The series/parallel conversion portion (S/P) 110 converts
the Q signal sequences (stream) in series into plural parallel
signal sequences, and thus outputs the parallel signal sequences to
the rate conversion portion 112.
[0164] The rate conversion portion 112 repeats a predetermined
number of times, for example, CRF times the Q single-carrier
signals output from the FFT portion 108. As a result, the number of
the single-carrier signals generated is N.sub.sub=Q.times.CRF. In
addition, the rate conversion portion 112 outputs the Q parallel
signal sequences which have been output from the series/parallel
conversion portion (S/P) 110 to the frequency domain signal
generation portion 114.
[0165] On the other hand, the radio resource allocation control
portion 122 controls time and frequency blocks allocated to each
physical channel in accordance with notification information
indicating radio resource allocation to each physical channel
imparted by the base station 200 and information indicating a
scheduling result for each user.
[0166] In addition, the radio resource allocation control portion
122 controls allocation the radio resources for a certain period
based on the time-scale of Transmission Time Interval (TTI) length
of plural frequency blocks when the frequency blocks and the time
are allocated to each physical channel.
[0167] Next, referring to FIGS. 13 and 14, shared data channel
scheduling is explained. The shared data channel is allocated in
accordance with the scheduling in the base station 200 as described
later.
[0168] The frequency blocks are allocated in accordance with
scheduling control information in the time domain in the frequency
division multiplexing access where the frequency is steadily
allocated, as shown in FIG. 13. In this case, plural frequency
blocks are allocated to high data rate users, which allows each
user to use only the frequency blocks allocated in advance. Thus,
the transmission apparatus 100 does not have to transmit in advance
pilot channels in other frequency blocks that are transmitted in
order that the reception apparatus 400 is capable of measuring a
channel quality indicator (CQI).
[0169] An optimal bandwidth of the frequency block is 1.25 to 5
MHz, for example. By widening the bandwidth of the frequency block,
the multi user diversity effect can be enhanced in the frequency
block.
[0170] When the single-carrier transmission is performed, the
bandwidth allocated to each user may be variable in accordance with
the data rate.
[0171] In addition, when the traffic size of a certain user is
larger than the payload size of the frequency block, one frequency
block may be exclusively used by one user.
[0172] A localized FDMA, which is a narrower FDMA arranged over the
frequency block, is used by plural low data rate users. Namely, the
spectrum utilized by each user is arranged over the block as
described with reference to FIGS. 2A and 2B. In addition, the
comb-shaped frequency spectrum utilized by each user may be
distributed over the entire band. Other users use the comb-shaped
spectrum. The localized FDMA may be mainly used in the shared data
channel.
[0173] Moreover, one band, for example, a frequency block may be
allocated to plural users, as shown in FIG. 14. In this case,
frequency multiplexing using the comb-shaped frequency spectrum is
used. Alternatively, plural users are multiplexed into one frame in
a manner described as follows. Chip information by a certain unit
is time-divisionally stored in TTI. This chip information is used
as a unit so as to change the frequency used for the transmission.
As stated, plural users are allocated to a certain band and
transmission is performed using the frequency hopping. By
allocating a certain frequency band to plural users, the
interference from other cells (sectors) is averaged out. Therefore,
fluctuations of the interference from other cells (sectors) can be
reduced compared to a situation where users are changed in a
certain frequency band so as to perform transmission.
[0174] Next, the following explanation is based on a situation
where a coverage area covered by the base station 200 is composed
of three sectors 250.sub.1, 250.sub.2, 250.sub.3; a mobile station
A300.sub.1 exists in the sector 250.sub.1; and a mobile station
B300.sub.2, a mobile station C300.sub.3, a mobile station
D300.sub.4, and a mobile station E300.sub.5 exist in the sector
250.sub.3, for example, as shown in FIG. 15.
[0175] When frequency blocks are allocated to each user, if another
mobile station in a neighboring sector exists near the mobile
station concerned, the interference power becomes larger, whereas
the interference power becomes lower if the other mobile station
exists far away.
[0176] For example, the mobile station A300.sub.1 existing in the
sector 250.sub.1 is largely influenced by the interference power
from the mobile station D300.sub.4 that exists in the neighboring
sector 250.sub.3 and is located near the mobile station A300.sub.1,
but not largely influenced by the interference power from the
mobile station E300.sub.5 existing far away. Therefore, the
interference power varies with time as shown in FIG. 16A.
[0177] On the other hand, when the frequency hopping and the
frequency division multiplexing access using the comb-shaped
frequency spectrum are performed, the interference power is
averaged out as a whole and becomes substantially constant, as
shown in FIG. 16B, which reduces time-wise variations of the
interference power. In this case, although the transmission power
per user is reduced, efficiency per user remains unchanged by
performing continuous allocation over plural time slots, thereby
reducing variations of the interference from other cells
(sectors).
[0178] In addition, the frequency blocks may be allocated in
accordance with control information on the scheduling in the time
domain and the frequency domain, as shown in FIG. 17.
[0179] In this case, the pilot channel which is transmitted in
order that the reception apparatus 400 measures the channel quality
indicator (CQI) is transmitted over all the frequency blocks,
namely, over all the channel bandwidths.
[0180] In addition, when a traffic size of a certain user is larger
than a payload size of the frequency block, one frequency block may
be exclusively used by one user.
[0181] When there are plural low data rate users, one frequency
block is used by plural users. In this case, orthogonal frequency
spectra, namely, the narrower FDMA (localized FDMA) which is
arranged over the frequency block, or the comb-shaped spectrum
(distributed FDMA) is applied to the same frequency block. Namely,
as described with reference to FIGS. 2A and 2B, the spectrum
utilized by each user is arranged over the block within the
frequency block. In addition, the frequency spectrum utilized by
each user may be distributed and arranged in the shape of a comb
over the frequency block, which reduces multi user
interference.
[0182] An optimal bandwidth of the frequency block is 0.3125 to
1.25 MHz, for example. By narrowing the bandwidth of the frequency
block and scheduling the channel in the frequency domain, the multi
user diversity effect can be enhanced.
[0183] When the single-carrier transmission is performed, the
bandwidth allocated to each user may be variable in accordance with
the data rate.
[0184] The narrower FDMA (localized FDMA) arranged over the
frequency block is used by plural low data rate users.
[0185] In addition, when the scheduling is performed in the time
domain and the frequency domain, the frequency blocks may be
grouped, which reduces an overhead of the pilot channel.
[0186] Additionally, the bandwidth may be changed in accordance
with the channel conditions, as shown in FIG. 18. For example, the
frequency band allocated to the system is divided into plural
frequency blocks so as to perform allocation. In this case, when
the channel conditions are good, plural frequency blocks, for
example, two frequency blocks are allocated (users A, B, and C),
and when the channel conditions are not good, fewer frequency
blocks than the frequency blocks allocated when the channel
conditions are good are allocated (user D) The single-carrier
transmission is performed in the frequency band so allocated, which
improves efficiency as a whole.
[0187] Referring to FIGS. 19A and 19B, frequency block grouping is
explained.
[0188] When the frequency block grouping is not performed, the
narrower FDMA (localized FDMA) which is arranged over the frequency
block, or the comb-shaped spectra is used by plural low data rate
users as shown in FIG. 19A.
[0189] As the frequency block grouping, there are a distributed
grouping where discrete frequency blocks form a group and a
localized grouping where consecutive frequency blocks form a group,
as shown in FIG. 19B.
[0190] As stated above, overhead of the pilot channel for use in
CQI measurement can be reduced by grouping the frequency blocks in
advance so as to perform scheduling in the frequency domain.
[0191] For example, the radio resource allocation determination
portion 404 of the reception apparatus provided in the base station
200 determines the time and frequency allocated to a
contention-based channel, for example, a random access channel or
reserve packet channel in accordance with a channel load or the
like, and thus imparts the corresponding allocation to each mobile
station through the down-link broadcast channel. For example, the
radio resource allocation determination portion 404 determines to
allocate the radio resources so that at least one portion of the
allocated frequency band is utilized, when the signal to be
transmitted is the contention-based channel.
[0192] In addition, the radio resource allocation determination
portion 404 of the reception apparatus provided in the base station
200 performs scheduling depending on the channel conditions and
determines the time and frequency allocated for a scheduling-base
channel, for example, the shared data channel or the like, and thus
imparts to each mobile station through the down-link broadcast
channel. Traffic data and layer 3 control messages are transmitted
through the shared data channel. In addition, when communicating
through the shared data channel, H-ARQ (hybrid automatic repeat
request) may be employed.
[0193] In addition, the radio resource allocation determination
portion 404 of the reception apparatus provided in the base station
200 performs scheduling, determines the time and frequency
allocated for the scheduling-based channel, for example, a channel
through which control information (referred to as a shared control
channel) is transmitted, and imparts the corresponding allocation
to each mobile station through the down-link broadcast channel.
[0194] The radio resource allocation control portion 122 controls
so that the contention-based channel and the scheduled channel are
multiplexed. For example, the radio resource allocation control
portion 122 controls so that the contention-based channel and the
scheduling-base channel are time-multiplexed, as shown in FIG. 20A.
In this case, the radio resource allocation control portion 122 may
perform an adaptive TTI length control and set the TTI length
longer, which reduces the ratio of the shared control channel
occupied in the entire length of the TTI, thereby reducing the
overhead of the shared control channel.
[0195] In addition, the radio resource allocation control portion
122 may control so that the contention-based channel and the
scheduling-base channel are frequency-multiplexed, for example, as
shown in FIG. 20B.
[0196] Moreover, the radio resource allocation control portion 122
may control so that the contention-based channel and the
scheduling-based channel are time-multiplexed and
frequency-multiplexed in a mixed manner. In this case, the radio
resource allocation control portion 122 may perform the adaptive
TTI length control and set the TTI length longer, which reduces the
ratio of the shared control channel occupied in the entire length
of the TTI, thereby reducing the overhead of the shared control
channel.
[0197] The frequency domain signal generation portion 114 shifts
each single-carrier signal on the frequency axis so that the
spectrum becomes comb-shaped. For example, when a process
corresponding to CRF=4 is carried out, three zeros are arranged for
every single-carrier signal or signal sequence. In addition, the
frequency domain signal generation portion 114 allocates a radio
resource to each physical channel according to the input radio
resource allocation information and depending on the physical
channel. When the single-carrier method is employed in such a
manner, the CRF value and the offset value that shifts each
single-carrier signal are changed, and the number of users is
changed.
[0198] The frequency domain signal generation portion 114 performs
mapping on each of the number Q of the parallel signal sequences,
arranges the signal sequence directly to the frequency component,
and allocates the radio resources to every mapped signal.
[0199] The IFFT portion 116 performs the fast Fourier
transformation on the comb-shaped spectrum obtained by shifting
each single-carrier signal on the frequency axis, and thus
generates a wave-shaped transmission spectrum of the single-carrier
method.
[0200] In addition, the IFFT portion 116 performs the fast inverse
Fourier transformation on the multi-carrier signal composed of
plural sub-carriers and performs the OFDM-method-based modulation,
thereby generating a wave-shaped transmission spectrum of the
multi-carrier method.
[0201] The guard interval (GI) addition portion 118 adds guard
intervals to signals to be transmitted and prepares a symbol of
either one of the OFDM method and the multi-carrier method. The
guard intervals are obtained by replicating a portion of the top or
end of a symbol to be transmitted.
[0202] The filter performs a band limitation on the transmission
signal. The band-limited signal is transmitted.
[0203] Next, the reception apparatus 400 according to this example
is explained referring to FIG. 21.
[0204] The reception apparatus 400 is provided in the base station,
for example, and transmits the down-link channel.
[0205] The reception apparatus 400 according to this example is
employed in the aforementioned cellular environment and local area
environment.
[0206] The reception apparatus 400 according to this example is
capable of receiving a signal transmitted in accordance with the
signal carrier method and the multi-carrier method. In addition,
the reception apparatus 400 includes the radio access method
determination portion 402 and the radio resource allocation
determination portion 404.
[0207] The radio access method determination portion 402 determines
a radio access method that the mobile station 300 is allowed to use
in accordance with the environment where the reception apparatus
400 is installed.
[0208] The radio access method determination portion 402 determines
use of the single-carrier method, for example, when the reception
apparatus 400 is installed in the cellular environment, and thus
imparts to the mobile station 300 the use of single-carrier method.
On the other hand, the radio access method determination portion
402 determines use of the multi-carrier method, for example, when
the reception apparatus 400 is installed in the local area
environment, and thus imparts to the mobile station 300 the use of
the multi-carrier method.
[0209] For example, when the base station 200 is installed, the
radio access method determination portion 402 determines the radio
access method used in accordance with a cell configuration, for
example, a cell radius, presence or absence of the neighboring
cells, or the like. For example, the single-carrier method is used
when the cell radius is large, whereas the multi-carrier method is
used when the cell radius is small. The radio access method
determination portion 402 imparts information indicating the
determined access method to the mobile stations 300, as common
control information for all the users.
[0210] In such a manner, the radio access method is determined when
the base station is installed, which leads to a simplified
configuration and control.
[0211] In addition, the access methods may be switched in
accordance with a distance between each user and the base station,
or a transmission power margin in each user.
[0212] For example, when the access methods are switched in
accordance with the distance between each user and the base station
200, a path-loss may be used, for example, as a quantity
corresponding to the distance between each user and the base
station 200. In this case, the mobile station 300 measures the
path-loss in the down-link using a reception power of the down-link
pilot signal, and thus imparts information indicating the measured
path-loss to the base station 200 over the up-link.
[0213] The radio access method determination portion 402 determines
that a distance between the base station 200 and the mobile station
300 is large when the received path-loss value is greater than a
predetermined threshold, determines use of single-carrier method,
and thus imparts the information to the mobile stations 300.
[0214] The radio access method determination portion 402 determines
that a distance between the base station 200 and the mobile station
300 is small when the received path-loss value is smaller than a
predetermined threshold, determines use of single-carrier method,
and imparts the information to the mobile stations 300 as common
control information for each user.
[0215] In such a manner, the radio access method is controlled for
each mobile station in accordance with the distance between the
base station and the mobile stations.
[0216] In addition, when the access methods are switched in
accordance with the transmission power margin in each user, "(the
maximum allowance transmission power)-(the current transmission
power)" may be used, for example, as an indicator of the margin in
the transmission power of each user. In this case, the mobile
stations impart a value indicating "the maximum allowance
transmission power--the current transmission power" to the base
station.
[0217] The radio access method determination portion 402 determines
that the transmission power margin is small when the value
indicating "the maximum allowance transmission power--the current
transmission power" is smaller than a predetermined threshold, and
determines use of the single-carrier method, which in turn is
imparted to the mobile stations 300.
[0218] On the other hand, the radio access method determination
portion 402 determines that the transmission power margin is large
when the value indicating "(the maximum allowance transmission
power) (the current transmission power)" is greater than the
predetermined threshold, and determines use of the multi-carrier
method, which in turn is imparted to the mobile stations 300.
[0219] According to the above, the access methods are controlled in
accordance with the performance of each mobile station.
[0220] In addition, the mobile stations 300 may transmit the
information indicating the maximum allowance transmission power and
the information indicating the current transmission power. Then,
the radio access method determination portion 402 may calculate
"the maximum allowance transmission power--the current transmission
power" and control the radio access methods in accordance with the
calculated value.
[0221] The radio resource allocation determination portion 404
determines allocation of the radio resource to each physical
channel, which in turn is imparted to the mobile station 300.
[0222] In addition, the radio resource allocation determination
portion 404 performs scheduling on each user, and thus reports the
results to the mobile station 300.
[0223] The radio resource allocation determination portion 404 may
allocate a radio resource for a certain time based on a time-scale
of the transmission time interval (TTI) length of plural frequency
blocks when allocating the time and frequency block to each
physical channel.
[0224] In addition, the radio resource allocation determination
portion 404 performs scheduling for the shared data channel.
[0225] The radio resource allocation determination portion 404
performs scheduling in the time domain in the frequency division
multiplexing access, and generates control information, as shown in
FIG. 13. In this case, plural frequency blocks are allocated to a
fast data rate user, which allows each user to use only the
frequency blocks allocated in advance. Therefore, the transmission
apparatus 100 does not have to receive a pilot channel of other
frequency blocks transmitted so as to allow the reception apparatus
400 to measure the channel quality indicator (CQI).
[0226] An optimal bandwidth of the frequency block is 1.25 to 5
MHz, for example. By widening the bandwidth of the frequency block,
the multi user diversity effect can be enhanced in the frequency
block.
[0227] When the single-carrier transmission is performed, the
bandwidth allocated to each user may be variable in accordance with
the data rate.
[0228] In addition, when a traffic size of a certain user is larger
than a payload size of the frequency block, one frequency block may
be exclusively used by one user.
[0229] Additionally, the bandwidth may be changed in accordance
with the channel conditions, as shown in FIG. 17.
[0230] The narrower FDMA (localized FDMA) which is arranged over
the frequency block may be used by plural low data rate users.
Namely, the spectrum utilized by each user is arranged over the
block as described with reference to FIGS. 2A and 2B. In addition,
the comb-shaped frequency spectrum utilized by each user may be
distributed over the entire band. Other users use the comb-shaped
spectra. The localized FDMA may be mainly used for the shared data
channel.
[0231] In addition, the radio resource allocation determination
portion 404 may perform scheduling in the time domain and the
frequency domain, and generate control information.
[0232] In this case, the pilot channel to be transmitted in order
to measure the channel quality indicator (CQI) is transmitted over
all the frequency blocks, namely, over all the channel
bandwidths.
[0233] In addition, when a traffic size of a certain user is larger
than a payload size of the frequency block, one frequency block may
be exclusively used by one user.
[0234] When there are plural low data rate users, one frequency
block is used by plural users. In this case, orthogonal frequency
spectra, namely, the narrower FDMA (localized FDMA) which is
arranged over the frequency block, or comb-shaped spectrum
(distributed FDMA) is applied to the same frequency block. Namely,
as described with reference to FIGS. 2A and 2B, the spectra
utilized by each user are arranged over the block in the frequency
block. In addition, the frequency spectrum utilized by each user
may be distributed and arranged in a shape of comb over the
frequency block, which reduces multi user interference.
[0235] An optimal bandwidth of the frequency block is 0.3125 to
1.25 MHz, for example. By narrowing the bandwidth of the frequency
block and performing scheduling of the channel in the frequency
domain, the multi user diversity effect can be enhanced in the
frequency block.
[0236] When the single-carrier transmission is performed, the
bandwidth allocated to each user may be variable in accordance with
the data rate.
[0237] The narrower FDMA (localized FDMA) which is arranged over
the frequency block may be used by plural low data rate users.
[0238] In this case, the frequency block may be grouped, which
reduces the overhead of the pilot channel.
[0239] Moreover, one band, for example, a frequency block may be
allocated to plural users, as shown in FIG. 14. In this case,
frequency multiplexing using the comb-shaped frequency spectrum is
used. Alternatively, plural users are multiplexed into one frame in
a manner described as follows. Chip information by a certain unit
is time-divisionally stored in TTI. This chip information is used
as a unit so as to change the frequency used for the transmission.
As stated, plural users are allocated to a certain band and
transmission is performed using the frequency hopping. By
allocating plural users to a certain frequency band, the
interference from other cells (sectors) can be averaged out.
Therefore, fluctuations of the interference from other cells
(sectors) can be reduced in a time-wise manner compared to a
situation where users are changed in a certain frequency band so as
to perform transmission.
[0240] Referring to FIG. 19, the frequency block grouping is
explained.
[0241] When the frequency block grouping is not performed, the
narrower FDMA (localized FDMA) which is narrowly arranged over the
frequency block, or comb-shaped spectra is used by plural low data
rate users.
[0242] As the frequency block grouping, there are a distributed
grouping where discrete frequency blocks form a group and a
localized grouping where consecutive frequency blocks form a
grouped.
[0243] As stated above, the overhead of the pilot channel for use
in CQI measurement can be reduced by grouping the frequency blocks
in advance so as to perform scheduling in the frequency domain.
[0244] For example, the radio resource allocation determination
portion 404 determines the time and frequency allocated for the
contention-based channel, for example, a random access channel or a
reserve packet channel in accordance with a channel load or the
like, and thus imparts the corresponding allocation to each mobile
station through the down-link broadcast channel. For example, the
radio resource allocation determination portion 404 determines the
allocation of the radio resource so that at least one portion of
the allocated frequency band is utilized, when the signal to be
transmitted is the contention-based channel.
[0245] In addition, the radio resource allocation determination
portion 404 performs scheduling depending on the channel conditions
and determines the time and frequency allocated to a scheduled
channel, for example, the shared data channel or the like, which in
turn is imparted to each mobile station through the down-link
broadcast channel. Traffic data and layer 3 control message are
transmitted through the shared data channel.
[0246] For example, the radio resource allocation determination
portion 404 groups channels in accordance with the channel
conditions, for example, the CQI measurement result so as to
perform allocation, which can reduce the overhead of the pilot
channel.
[0247] In addition, when communications are made through the shared
data channel, an H-ARQ (hybrid automatic repeat request) may be
employed.
[0248] In addition, the radio resource allocation determination
portion 404 performs scheduling, and determines the time and
frequency allocated to the shared control channel, which in turn
are imparted to each mobile station through the down-link broadcast
channel.
[0249] Next, referring to FIG. 22, a configuration of the receiver
that changes bands in accordance with the channel conditions so as
to perform allocation is explained.
[0250] A receiver 400 has the same configuration as the reception
apparatus explained with reference to FIG. 21.
[0251] The radio resource allocation determination portion 404 of
the receiver 400 comprises a reception characteristic measurement
portion 406, a ranking portion 408 connected to the reception
characteristic measurement portion 406, a frequency block
allocation portion 410 connected to the ranking portion 408, a
reception power determination portion 412 connected to the
frequency block allocation portion 410, and an MCS determination
portion 414 connected to the reception power determination portion
412.
[0252] The reception characteristic measurement portion 406
measures a reception characteristic, for example, the received SINR
in each frequency block, for all users. All the users transmit
pilot signals in the entire band. The reception characteristic
measurement portion 406 measures the reception conditions, for
example, the received SINR in each band. In addition, when the
users transmit the pilot signals using a part of the frequency band
in the entire frequency band (system bandwidth), the received SINR
at each allocation unit in the frequency band determined in
advance, for example, at each frequency block is measured, as shown
in FIG. 23A. Namely, the reception characteristic measurement
portion 406 measures the reception characteristics of the
transmitted pilot signals using the allocation unit of the
frequency band determined in advance as a measurement unit.
[0253] When the users transmit the pilot signals using a part of
frequency band in the entire frequency band, the reception
characteristic measurement portion 406 may measure the reception
conditions in the part of the frequency band, as shown in FIG. 23B.
Namely, the reception characteristic measurement portion 406
measures the reception characteristics of the transmitted pilot
signals using the requested allocation unit, for example, the pilot
signal transmission frequency as a measurement unit.
[0254] The ranking portion 408 determines priorities in accordance
with the measured reception characteristic and ranks the priorities
in a predetermined order, for example, in order of higher received
SINR, so as to generate a ranking table. In addition, the ranking
portion 408 may generate the ranking table in accordance with at
least one of a reception condition of the pilot signal transmitted
from each mobile station, the reception condition being measured in
the base station, (in other words, a reception power measured in
the reception apparatus about the channel condition measurement
signal), a waiting time and a type of data to be transmitted from
each mobile station, and the maximum transmission power of each
mobile station. As a result, a mobile station to which a frequency
band is to be allocated is determined for each frequency allocation
unit.
[0255] The frequency block allocation portion 410 allocates a
frequency block in accordance with the generated ranking table. For
example, the frequency block allocation portion 410 performs
tentative allocation of the frequency block to be allocated to a
high priority user. In addition, the frequency block allocation
portion 410 allocates the tentatively allocated block and the
adjacent frequency blocks to the user of the highest priority.
Moreover, the frequency block allocation portion 410 ranks the
priorities in higher order, excluding the priorities corresponding
to the user and the frequency blocks which have been already
allocated, so as to re-rank the table and repeats the same
procedures. In such a manner, continuous frequency bands are
allocated to one apparatus in accordance with the reception
characteristics for each transmission apparatus.
[0256] In this case, the frequency block allocation portion 410
allocates a frequency band within a range of the transmission
frequency of the pilot signal, as shown in FIG. 24A. Moreover, the
frequency block allocation portion 410 may allocate a frequency
band per allocation unit of, for example, an integral multiple of
frequency bands, as shown in FIG. 24B.
[0257] Furthermore, when the mobile station transmits the pilot
signal for every band allocation unit based on frequency hopping,
the frequency block allocation portion 410 may perform scheduling
on the band in which the pilot signal is transmitted, and allocate
the data channels, as shown in FIG. 25A. In addition, the band in
which the pilot signal is transmitted is assigned so as to deviate
with time. In this case, the frequency block allocation portion 410
determines the data channel for each band where the pilot signal
has been transmitted. In this case, the scheduling cycle becomes
longer.
[0258] For example, at time t, all the mobile stations, for
example, MS1, MS2, MS3, and MS4 transmit the pilot signals in the
same band. The frequency block allocation portion 410 performs
scheduling among the mobile stations that transmit the pilot
signals in the same band. In this case, the scheduling is performed
among the mobile stations MS1, MS2, MS3, and MS4, and the data
channel is allocated to the mobile station MS3.
[0259] At time (t+1), the mobile stations MS1, MS2, MS3, and MS4
transmit the pilot signals in bands different from the bands in
which the pilot signals have been transmitted at time t. For
example, the mobile stations MS1, MS2, MS3, and MS4 transmit the
pilot signals in the band adjacent to the bands in which the pilot
signals have been transmitted at time t. The frequency block
allocation portion 410 performs scheduling on the mobile stations
that transmit the pilot signals in the same band. In this case, the
scheduling is performed among the mobile stations MS1, MS2, MS3,
and MS4, and the data channel is allocated to the mobile station
MS2.
[0260] At time (t+2), the mobile stations MS1, MS2, MS3, and MS4
transmit the pilot signals in bands different from the bands in
which the pilot signals have been transmitted at time (T+1). For
example, the mobile stations MS1, MS2, MS3, and MS4 transmit the
pilot signals in the bands adjacent to the bands in which the pilot
signals have been transmitted at time (t+1). The frequency block
allocation portion 410 performs scheduling on the mobile stations
that transmit the pilot signals in the same band. In this case, the
scheduling is performed on the mobile stations MS1, MS2, MS3, and
MS4, and the data channel is allocated to the mobile station MS2.
Then, the data channel allocation is repeated.
[0261] By the way, when each mobile station independently transmits
the pilot signal based on frequency hopping, the frequency block
allocation portion 410 may perform scheduling for every frequency
allocation unit on the mobile stations that transmit the pilot
signals in the bands, so as to allocate the data channel. For
example, a band adjacent to the band that has been already
allocated is allocated to a certain mobile station.
[0262] For example, at time t, the mobile stations, for example,
MS3, MS4, MS5, and MS6 transmit the pilot signals in different
bands; the mobile station MS1 transmits the pilot signal in the
bands in which the mobile stations MS3 and MS4 transmit the pilot
signals; and the mobile station MS2 transmits the pilot signal in
the bands in which the mobile stations MS5 and MS6 transmit the
pilot signals.
[0263] The frequency block allocation portion 410 performs
scheduling on the mobile stations that transmit the pilot signals
in corresponding bands. The frequency block allocation portion 410
performs scheduling for each band-allocation unit. For example, the
frequency block allocation portion 410 performs scheduling on the
mobile stations MS1 and MS3 and allocates the data channel to the
mobile station MS1; performs scheduling on the mobile stations MS1
and MS2 and allocates the data channel to the mobile station MS4;
performs scheduling on the mobile stations MS2 and MS5 and
allocates the data channel to the mobile station MS5; and performs
scheduling on the mobile stations MS2 and MS6 and allocates the
data channel to the mobile station MS2.
[0264] At time (t+1), the mobile stations, for example, MS3, MS4,
MS5, and MS6 transmit the pilot signals in different bands. For
example, the pilot signals are transmitted in bands adjacent to the
bands where the pilot signals were transmitted at time t. In
addition, the mobile stations, for example, MS1 and MS2 transmit
the pilot signals in different bands. For example, the pilot
signals are transmitted in bands adjacent to the bands in which the
pilot signals have been transmitted at time t.
[0265] The frequency block allocation portion 410 performs
scheduling on the mobile stations that transmit the pilot signals
in corresponding bands. The frequency block allocation portion 410
performs scheduling for each band-allocation unit. For example, the
frequency block allocation portion 410 performs scheduling on the
mobile stations MS2 and MS6 and allocates the data channel to the
mobile station MS2; performs scheduling on the mobile stations MS2
and MS3 and allocates the data channel to the mobile station MS2;
performs scheduling on the mobile stations MS1 and MS4 and
allocates the data channel to the mobile station MS4; and performs
scheduling on the mobile stations MS1 and MS5 and allocates the
data channel to the mobile station MS5.
[0266] At time (t+2), the mobile stations, for example, MS3, MS4,
MSS, and MS6 transmit the pilot signals in different bands. For
example, the pilot signals are transmitted in bands adjacent to the
bands in which the pilot signals have been transmitted at time
(t+1). In addition, the mobile stations M1 and M2 transmit the
pilot signals in different bands. For example, the pilot signals
are transmitted in bands adjacent to the bands where the pilot
signals have been transmitted at time (t+1).
[0267] The frequency block allocation portion 410 performs
scheduling on the mobile stations that transmit the pilot signals
in each band. The frequency block allocation portion 410 performs
scheduling for each band-allocation unit. For example, the
frequency block allocation portion 410 performs scheduling on the
mobile stations MS1 and MS5 and allocates the data channel to the
mobile station MS5; performs scheduling on the mobile stations MS1
and MS6 and allocates the data channel to the mobile station MS6;
performs scheduling on the mobile stations MS2 and MS3 and
allocates the data channel to the mobile station MS2; and performs
scheduling on the mobile stations MS2 and MS4 and allocates the
data channel to the mobile station MS4.
[0268] Furthermore, when each mobile station independently
transmits the pilot signal based on frequency hopping, the
frequency block allocation portion 410 may allocate the data
channel in each band-allocation unit using the past reception
quality as the reception characteristic (reception quality) in the
case of the band in which the pilot signals are not transmitted,
shown in FIG. 25C. In this case, there may be plural mobile
stations that transmit the pilot signals in the same frequency
band.
[0269] For example, at time t, the mobile stations, for example,
MS1, MS2, MS3, and MS4 transmit the pilot signals in different
bands.
[0270] The frequency block allocation portion 410 performs
scheduling on the mobile stations that transmit the pilot signals
in corresponding band. The frequency block allocation portion 410
performs scheduling for each band-allocation unit.
[0271] At time (t+1), the mobile stations, for example, MS1, MS2,
MS3, and MS4 transmit the pilot signals in different bands. For
example, the pilot signals are transmitted in bands adjacent to the
bands in which the pilot signals have been transmitted at time
t.
[0272] The frequency block allocation portion 410 performs
scheduling among the mobile stations that transmit the pilot
signals in corresponding bands. The frequency block allocation
portion 410 performs scheduling for each band-allocation unit using
the past reception quality as the reception characteristic
(reception quality) in the case of the band in which the pilot
signals are not transmitted.
[0273] At time (t+2), the mobile stations, for example, MS1, MS2,
MS3, and MS4 transmit the pilot signals in different bands. For
example, the pilot signals are transmitted in bands adjacent to the
band in which the pilot signals have been transmitted at time
(t+1).
[0274] The frequency block allocation portion 410 performs
scheduling on the mobile stations that transmit the pilot signals
in corresponding bands. The frequency block allocation portion 410
performs scheduling for each band-allocation unit using the past
reception quality as the reception characteristic (reception
quality) in the case of the band in which the pilot signals are not
transmitted.
[0275] When it is assumed that there are small fluctuations in the
channel conditions and the band in which the pilot signal is
transmitted is not changed, if the channel conditions of the band
are impaired, the reception characteristic of the band remains
impaired. Therefore, by changing the bands in which the pilot
signals are transmitted, the reception characteristic can be
improved.
[0276] Furthermore, when the data channel is allocated to the
frequency allocation band, the band that has once been allocated is
not changed as long as the reception conditions change to a certain
degree, as shown FIG. 26. Namely, once the frequency block
allocation portion 410 allocates a frequency band, the frequency
block allocation portion 410 continues to allocate continuously the
frequency band until the reception power of the channel conditions
measurement signal in the frequency band in the reception apparatus
exceeds a threshold determined in advance. For example, when the
channel conditions in the allocated band change to exceed the
predetermined threshold, the band is released and reallocation is
performed taking account of the channel conditions of each mobile
station. With this, the interference from other cells (sectors) can
be reduced. The receiver 400 changes modulation methods depending
on the reception conditions before applying AMC. Changes in the
conditions after the modulation method or the like is determined
impair normal reception. Namely, the reception conditions in the
up-link are interfered with by other cells (sectors), especially
other close-by users. For example, when the mobile station
A300.sub.1 is transmitting while the mobile station D300.sub.4 that
exists in the adjacent sector 250.sub.3 in FIG. 15 is transmitting,
the mobile station A300.sub.1 is influenced by the interference
from the mobile station D300.sub.4.
[0277] When the mobile station A300.sub.1 is transmitting while the
mobile station B300.sub.2 that exists in the adjacent sector
250.sub.3 is transmitting, the mobile station A300.sub.1 is
interfered by the mobile station B300.sub.2. The mobile station
A300.sub.1 determines a modulation method depending on a ratio of
the requested radiowaves over the interference radiowaves. When the
frequency band allocated to the mobile station B300.sub.2 is
switched to the mobile station C300.sub.4, the quantity of the
interference is increased. While the mobile station A300.sub.1
determines the MCS taking account of the interference signals from
the mobile station B300.sub.2, if the frequency allocation is
suddenly performed so that the frequency band is switched to the
C300.sub.4, the quantity of the interference from the adjacent
sectors is increased, which makes it impossible for the reception
station to perform reception by the firstly determined modulation
method.
[0278] In order to avoid such situation, the band that has once
been allocated cannot be changed as long as changes in the
reception conditions do not become a certain level or more. When
the reception conditions become a certain level or more, for
example, a certain threshold, the band is released and reallocation
is performed in accordance with the channel conditions of each
mobile station.
[0279] The reception power determination portion 412 assigns the
up-link transmission power to the mobile station to which the
frequency band is allocated. In this case, the up-link transmission
power is assigned to the mobile station (transmitter) to which the
frequency band is allocated in accordance with the allocated
frequency bandwidth. For example, the maximum power with which the
mobile station (transmitter) can transmit has been determined.
There is described in the following a situation where the
transmission power for the allocated band is, for example, X as
shown in FIG. 27A. If the allocated band is broadened, for example,
doubled, the transmission power is halved to be X/2, as shown in
FIG. 27B. The transmission power is determined in accordance with
the allocated bandwidth in such a manner. The reception power
determination portion 412 transmits the scheduling result and
information indicating the transmission power to the transmitter.
This set of information is input to the radio resource allocation
control portion 122.
[0280] For example, when the transmission power for a certain
allocation band has a maximum value at X, if the allocated band is
broadened, for example, doubled, the peak of the transmission power
is halved to be X/2.
[0281] The reception power de-termination portion 412 transmits the
scheduling result and information indicating the transmission power
to the transmitter. This set of information is input to the radio
resource allocation control portion 122. As a result, the mobile
station performs the up-link transmission with the maximum
transmission power in the allocated frequency band.
[0282] By converging the power in a certain band as stated above,
the power of the requested radiowaves can be increased. Especially,
when the power is converged in a certain band so as to perform
transmission by a mobile station existing far away from the base
station (reception apparatus), the base station can receive a
signal with a higher power, thereby improving the reception
quality.
[0283] The reception power determination portion 412 may measure
the interference power in the band to be allocated and assign the
transmission power using the interference power so that the ratio
of the requested radiowaves power over the interference power
becomes a predetermined value.
[0284] In this case, the transmission power that yields the
intended ratio of the requested radiowaves power over the
interference power may become the transmission power or more which
the mobile station can output. In this case, the transmission power
which the mobile station can output is assigned. On the other hand,
when the transmission power that yields the intended ratio of the
requested radiowaves power over the interference power is lower
than or equal to the transmission power with which the mobile
station can transmit, the transmission power that yields the
intended ratio of the requested radiowaves power over the
interference power is assigned.
[0285] In such a manner, the transmission power can be controlled
in accordance with the reception quality in the base station.
[0286] In addition, the mobile station performs the up-link signal
transmission with the maximum transmission power in the allocated
frequency band. The base station can perform reception of a higher
power signal, thereby improving the reception quality.
[0287] In addition, regarding the transmission power, the mobile
station may perform the up-link transmission with a constant
transmission power density regardless of the allocated frequency
bandwidth. For example, the radio resource allocation control
portion 122 performs transmission with the transmission power in
accordance with a predetermined frequency bandwidth, even when a
frequency band narrower than the predetermined frequency band is
allocated, as shown in FIGS. 28A and 28B. Since transmission is
performed at a constant transmission power per band as stated
above, the interference with other cells (sectors) can be less
influential.
[0288] The transmission power may be changed depending on the
position of the mobile station. Namely, it may be determined
whether the up-link transmission is performed with the maximum
transmission power in the allocated frequency band, or with a
constant transmission power density regardless of the allocated
frequency band. Then, the transmission power may be determined by
the determined method and information indicating the transmission
power may be imparted.
[0289] The base station may assign a modulation method and an error
correction code rate in the up-link transmission to the mobile
station to which the frequency band is allocated.
[0290] The modulation method and the error correction code rate may
be determined in accordance with the ratio of the requested
radiowaves power over the interference power in the MCS
determination portion 414 of the base station. Here, an
instantaneous value or an average value of the requested radiowaves
power and the interference may be used. For example, when the
transmission apparatus to which the frequency band is allocated
transmits a signal in accordance with the assigned transmission
power and the reception power of the channel conditions measurement
signal, either the instantaneous value or the average value is used
in accordance with the reception power and the interference power
in the reception apparatus that receives the signal that the
transmission apparatus transmits, the reception power and the
interference power being estimated in the allocated frequency.
Then, the modulation method and the error correction code rate are
determined in accordance with the ratio of the reception power over
the interference power.
[0291] There is described a situation where the mobile station
performs the up-link transmission with the maximum transmission
power in the allocated frequency band, for example. The
interference power fluctuates largely in the up-link. When the
modulation method is determined in accordance with the
instantaneous reception power, the interference power level
fluctuates depending on the time required to start transmitting.
Therefore, when such transmission is performed, average values of
the reception power, the requested radiowaves, and the interference
power are used.
[0292] Then, there is described a situation where the up-link
transmission is performed with a constant transmission density
regardless of the allocated frequency bandwidth. When control is
performed under such a situation where the interference power
fluctuations are small, the instantaneous values of the reception
power, the requested radiowaves, and the interference power are
used.
[0293] When the MCS determination portion 414 assigns the MCS when
the mobile station allowed to perform transmission transmits the
data channel, the MCS determination portion 414 may assign the MCS
in accordance with the reception quality of the pilot signal
measured for each frequency allocation unit in the allocated band
when the received SINR is measured for each frequency allocation
unit by the reception characteristic measurement portion 406, as
shown in FIG. 29. For example, the received SINR measured for each
allocation unit is used and thus the MCS is assigned in accordance
with at least one of the average SINR, the highest SINR, and the
lowest SINR.
[0294] In addition, a receiver that performs allocation so as to
change a bandwidth in accordance with the channel conditions may be
configured as shown in FIG. 30.
[0295] A receiver 400 has substantially the same configuration as
the receiver explained with reference to FIG. 21 and is different
from the receiver explained with reference to FIG. 2 in that a
pilot signal assignation portion 416 connected to the reception
characteristic measurement portion 406 is provided.
[0296] The pilot signal assignation portion 416 receives at least
one of information indicating the requested (maximum) transmission
frequency bandwidth of the data channel transmitted from a mobile
station, information indicating the quantity of data to be
transmitted, and information indicating data rate. In addition, the
pilot signal assignation portion 416 receives the information
indicating the requested (maximum) transmission bandwidth of the
pilot signal from the mobile station. The pilot signal assignation
portion 416 assigns a transmission bandwidth of the pilot signal to
the mobile station. For example, the pilot signal assignation
portion 416 determines the transmission bandwidth and center
frequency of the pilot signal in accordance with the information
indicating the requested (maximum) transmission bandwidth of the
pilot signal for each mobile station, and transmits information
indicating the determined transmission bandwidth and center
frequency of the pilot signal to the corresponding mobile stations.
In addition, the pilot signal assignation portion 416 may impart
information indicating the determined transmission bandwidth and
center frequency of the pilot signal to the corresponding
transmission apparatuses by transmitting the frequency block ID. In
this case, the pilot signal assignation portion 416 may assign
plural frequency blocks.
[0297] For example, the pilot signal assignation portion 416
assigns a narrower bandwidth than the maximum bandwidth requested
by the mobile station (requested (maximum) bandwidth) when
determining that the reception quality of the pilot signal is
insufficient even when the mobile station transmits the pilot
signal in the requested (maximum) bandwidth, because of a large
distance to the base station. For example, the pilot signal
assignation portion 416 assigns the transmission bandwidth of the
pilot signal in accordance with the maximum transmission power of
each mobile station and a path-loss between the base station and
each mobile station.
[0298] Moreover, the pilot signal assignation portion 416 assigns
the transmission bandwidth and center frequency of the pilot signal
of each mobile station so that deviation of the reception power of
the pilot signal measured in the frequency domain in the base
station is reduced or not caused, when assigning the transmission
bandwidth and center frequency of the pilot signal of each mobile
station, as shown in FIG. 32. For example, the pilot signal
assignation portion 416 determines in advance a reference value
indicating the deviation of the reception power of each pilot
signal and determines the transmission bandwidth and center
frequency of the pilot signal so that the deviation is kept at the
reference value or below. In this case, the pilot signal
assignation portion 416 calculates a total reception power of the
pilot signals of the mobile stations in the up-link in the base
station, and assigns the transmission bandwidth and center
frequency of the pilot signal of each mobile station so that the
deviation of the transmission bandwidth becomes smaller in the
frequency domain.
[0299] Moreover, when the pilot signal assignation portion 416
allows the mobile stations to transmit the pilot signal based on
the IFDMA method, the pilot signal assignation portion 416
determines the frequency bandwidth and a repetition factor of the
pilot signal of each mobile station so that each frequency
component is used without excess or deficiency, as shown in FIG.
33A. Namely, an amount of frequency shift is determined and
transmission is performed based on the frequency division
multiplexing method. In this case, a frequency offset is given so
that there is no band shared by the same user. For example, the
pilot signal assignation portion 416 assigns the transmission
bandwidth and center frequency of the pilot signal transmitted by
each mobile station in accordance with a remaining number of the
repetition factor. In this case, the pilot signal assignation
portion 416 assigns and imparts the repetition factor, the
frequency bandwidth, and the center frequency of the pilot
signal.
[0300] Furthermore, the pilot signal assignation portion 416
assigns the transmission band of the channel conditions measurement
signal so that the number of the mobile stations that transmit the
channel measurement signal does not vary in each frequency band.
For example, the pilot signal assignation portion 416 allocates the
transmission band of the channel measurement signal to every mobile
station, starting from the mobile stations having a broader
transmission band. In this case, the transmission bandwidth is, for
example, 2.sup.n times the minimum transmission bandwidth.
[0301] There is explained a situation where the numbers of mobile
stations having transmission bandwidths of 5 MHz, 2.5 MHz, and 1.25
MHz are N.sub.5, N.sub.2.5, and N.sub.1.25 in the system bandwidth
of 10 MHz, for example. In this case, the minimum transmission
bandwidth, for example, the frequency block bandwidth is assumed to
be 1.25 MHz.
[0302] (1) Random numbers are given to variables .PHI..sub.5MHz,
.PHI..sub.2.5MHz, and .PHI..sub.1.25MHz. Here, the random numbers
are integers.
[0303] (2) The frequency block ID and 4 blocks (=5/1.25 blocks from
((.PHI..sub.5MHz+n.sub.5) mod(10/5).times.(10/5)) are allocated to
n.sub.5-th mobile station having the transmission bandwidth of 5
MHz.
[0304] (3) The frequency block ID and 2 blocks (=2.5/1.25 blocks
from (((.PHI..sub.5MHz+N.sub.5+n.sub.2.5)
mod(10/5).times.(10/5)+(.PHI..sub.2.5MHz+n.sub.2.5)
mod(5/2.5).times.(5/2.5)) are allocated to n.sub.25-th mobile
station having the transmission bandwidth of 2.5 MHz.
[0305] (4) The frequency block ID and 1 block (=1.25/1.25 block
from ((.PHI..sub.5MHz+N.sub.5+N.sub.2.5+n.sub.1.25)
mod(10/5).times.(10/5)+(.PHI..sub.2.5MHz+N.sub.2.5+n.sub.1.25)
mod(5/2.5).times.(5/2.5)+(.PHI..sub.1.25MHz+N.sub.2.5+n.sub.1.25)
mod(2.5/1.25).times.(2.5/1.25)) are allocated to n.sub.25-th mobile
station having the transmission bandwidth of 2.5 MHz.
[0306] For example, in the case of N.sub.5=3, N.sub.25=3,
N.sub.1.25=4, .PHI..sub.5MHz, .PHI..sub.2.5MHz, and
.PHI..sub.1.25MHz=0, the band allocation in a sector is performed
on a mobile station by mobile station basis, from the mobile
stations having a broader transmission bandwidth, as shown in FIG.
33B.
[0307] The pilot signal assignation portion 416 performs the
aforementioned allocation at a predetermined cycle since the
transmission bandwidth and the number of the mobile stations in the
sector change because of a path-loss change due to movement of a
mobile station and/or handover.
[0308] When the mobile station is transmitting the pilot signal
using the requested (maximum) transmission frequency bandwidth, the
reception characteristic measurement portion 406 measures the
received SINR using the requested frequency bandwidth (requested
allocation bandwidth) of the data channel as a measurement unit, as
shown in FIG. 34.
[0309] The frequency block allocation portion 410 allocates the
frequency bands to each mobile station within a range of the
transmission band of the pilot signal in accordance with
information indicating the measured received SINR, the transmission
band of the pilot signal, and the desired frequency bandwidth of
the data channel. In this case, the frequency block allocation
portion 410 may perform allocation using the frequency allocation
unit determined in advance, for example, the frequency block as a
unit.
[0310] The MCS determination portion 414 assigns the MCS to the
mobile station that is allowed for transmission in accordance with
the reception quality of the pilot signal in the allocated band, as
shown in FIG. 35.
[0311] Next, referring to FIG. 36, operations of the transmission
apparatus 100 according to this example are explained.
[0312] The base station 200 determines the radio access method used
by the mobile station 300 and imparts the method to the mobile
station 300.
[0313] First, information indicating the radio access method is
received (step S1302).
[0314] Next, the switching portion 106 determines whether the
information indicating the radio access method indicates the
single-carrier method (step S1304).
[0315] When the received information indicating the radio access
method indicates the single-carrier method (step Sl3O4: YES), the
switching portion 106 switches to the single-carrier method.
Namely, the switching portion 106 outputs the input spread chip
sequence to the FFT portion 108.
[0316] Next, the frequency domain signal generation portion 114
determines whether the transmission data is assigned to a
contention-based channel (step S1308).
[0317] When the transmission data is assigned to the
contention-based channel (step S1308: YES), the frequency domain
signal generation portion 114 allocates a radio resource to the
contention-based channel in accordance with the input radio
resource allocation information. The transmission data to which the
radio resource are allocated is transmitted (step S1310).
[0318] On the other hand, when the transmission data is not the
contention-based channel, or the scheduling-based channel (step
S1308: NO), the frequency domain signal generation portion 114
allocates the radio resource to the scheduling-based channel in
accordance with the input radio resource allocation information.
The transmission data to which the radio resource is allocated are
transmitted (step S1312).
[0319] When the received information indicating the radio access
method indicates the multi-carrier method (step S1304: NO), the
switching portion 106 switches to the multi-carrier method. Namely,
the switching portion 106 outputs the input spread chip sequence to
the S/P conversion portion 110 (step S1314).
[0320] Next, the frequency domain signal generation portion 114
determines whether the transmission data is assigned to a
contention-based channel (step S1316).
[0321] When the transmission data is assigned to the
contention-based channel (step S1316: YES), the frequency domain
signal generation portion 114 allocates the radio resource to the
contention-based channel in accordance with the input radio
resource allocation information. The transmission data to which the
radio resource are allocated is transmitted (step S1318).
[0322] On the other hand, when the transmission data are not
assigned to the contention-based channel, or the scheduling-based
channel (step S1316: NO), the frequency domain signal generation
portion 114 allocates the radio resource to the scheduling-based
channel in accordance with the input radio resource allocation
information. The transmission data to which the radio resource is
allocated are transmitted (step S1320).
[0323] Next, referring to FIG. 37, operations of the reception
apparatus 400 according to this example are explained.
[0324] First, the radio access method determination portion 402
determines the radio access method used by the mobile station
300.
[0325] Next, there is explained a situation where the radio access
method determination portion 402 determines the single-carrier
method as the radio access method used by the mobile station
300.
[0326] The reception characteristic measurement portion 406
measures priority in each frequency block, for example, the
received SINR for all users (step S2602). The priorities
corresponding to the number of frequency blocks are obtained for
each user.
[0327] Next, the ranking portion 408 ranks priorities of "(the
number of the users).times.(the number of the frequency blocks)" in
higher order, and associates the users with the frequency blocks,
so as to generate a ranking table (step S2604).
[0328] When all the users transmit the pilot channels using the
entire band, the number of ranks in the ranking table is equal to
the number of the users times the number of the frequency blocks.
When the users transmit the pilot channels using different
frequency bands, there is no rank corresponding to the frequency
block in which the users do not transmit the pilot channels. For
example, when a certain user transmits the pilot channel using 5
frequency blocks out of 8 frequency blocks, there are no ranks
corresponding to the remaining 3 frequency blocks in the ranking
table.
[0329] Next, the frequency block allocation portion 410 performs
tentative allocation of the frequency blocks to the users, on a
user-by-user basis according to higher order of priorities (step
S2606).
[0330] The frequency block allocation portion 410 refers to the
ranking table and allocates the frequency blocks corresponding to
the users in higher order of priorities. For example, the user A is
ranked number 1 and the frequency block corresponding to the user A
is 4, according to the ranking table. In this case, "A1" indicating
the user A and the rank #1 is written into the frequency block 4.
Similarly, "A2" indicating the user A and the rank #2 is written
into the frequency block 5. The same procedures being repeated, the
tentative allocation is performed.
[0331] Next, the frequency block allocation portion 410 performs
allocation of the continuous frequency blocks among the frequency
blocks tentatively allocated to the highest priority user (step
S2608).
[0332] The frequency blocks 3 through 5 and the frequency block 8
are allocated to the user A. However, the band including the
highest rank frequency block is allocated because of the
single-carrier method. In other words, the frequency blocks 3
through 5 are allocated.
[0333] Next, the frequency block allocation portion 410 determines
whether all the frequency blocks are allocated, or whether all the
users are allocated (step S2610).
[0334] When all the frequency blocks are allocated or all the users
are allocated (step S2610: YES), the transmission power and the MCS
are determined for all the users to which the frequency blocks are
allocated (step S2614).
[0335] On the other hand, when all the frequency blocks or all the
users are not allocated (step S2610: NO), the frequency block
allocation portion 410 ranks in higher order of priorities the
priorities except for the priority of the user(s) to which the
frequency blocks are allocated (step S2612), and returns to step
S2606.
[0336] In this case, since the frequency blocks 3 through 5 have
been allocated to the user A, the above procedures are repeated
excluding the frequency blocks 3 through 5.
[0337] In such a manner, the bands having good channel conditions
are allocated to each user. Not discrete frequency blocks but
continuous frequency blocks can be allocated to each user.
[0338] Next, referring to FIG. 38, operations of another reception
apparatus 400 according to this example are explained.
Specifically, the operations of the reception apparatus 400
explained with reference to FIG. 30 is explained. As stated above,
the reception apparatus 400 is included in the base station and the
transmission apparatus 100 is included in the mobile station.
[0339] First, the radio access method determination portion 402
determines a radio access method used by the mobile station
300.
[0340] In the following, there is explained a situation where the
radio access method determination portion 402 determines the
single-carrier method as the radio access method used by the mobile
station 300.
[0341] The pilot channel generation portion transmits to a mobile
station at least one of information indicating the requested
(maximum) transmission frequency bandwidth of the data channel to
the base station, information indicating a quantity of data to be
transmitted, and information indicating a data rate. In addition,
the pilot channel generation portion imparts information indicating
the requested maximum transmission bandwidth of the pilot signal
(step S3802).
[0342] The pilot signal assignation portion 416 determines the
frequency bandwidth and center frequency of the pilot signal
transmitted by the mobile station in accordance with the
information indicating the requested maximum transmission bandwidth
of the pilot signal (step S3804), and imparts information
indicating the determined frequency bandwidth and center frequency
of the pilot signal to the mobile station (step S3806) In addition,
the pilot signal assignation portion 416 may impart information
indicating the determined center frequency and transmission
bandwidth of the pilot signal to corresponding transmission
apparatuses by transmitting a frequency block. ID. In this case,
the pilot signal assignation portion 416 may assign plural
frequency blocks. For example, the pilot signal assignation portion
416 assigns the transmission bandwidth in accordance with the
maximum transmission power of each mobile station and a path-loss
between the base station and each mobile station.
[0343] The pilot channel generation portion transmits the pilot
signal in accordance with the information indicating the imparted
center frequency and the frequency bandwidth (step S3808). In this
case, the pilot signal generation portion may transmit the pilot
signal based on the frequency hopping.
[0344] The reception characteristic measurement portion 406
measures the received SINR of the pilot signal. In addition, the
frequency block allocation portion 410 determines a mobile station
to which a frequency band is allocated in accordance with the
received SINR of the F pilot signal. Moreover, the MCS
determination portion 414 determines the MCS for the mobile station
to which is allocated the frequency band and which is allowed to
perform transmission (step S3810). Here, the transmission power
determination portion 412 may determine the transmission power for
the mobile station to which is allocated the frequency band and
which is allowed to perform transmission.
[0345] The radio resource allocation determination portion 404
imparts to the mobile station that is allowed to perform
transmission information indicating the data channel allocation
band (chunk, frequency blocks) and the MCS to be used (step
S3812).
[0346] The information indicating the data channel allocation band,
which is transmitted from the base station, is input to the radio
resource allocation control portion 122, and the MCS information is
input to the spreading and channel code portion 102.
[0347] The spreading and channel code portion 102 performs channel
coding by applying the error correction code such as the turbo code
or the convolution code to the input binary information sequence in
accordance with the input MCS information, and thus modulates the
channel-coded data.
[0348] The frequency domain signal generation portion 114
determines the data size in accordance with the allocated
bandwidth. The information indicating the user ID, MCS,
discriminator of new/retransmission, and data size is multiplexed
onto the control channel. As a result, the transmission frame is
generated (step S3814).
[0349] Next, the mobile station transmits the data channel (step
S3816).
[0350] The data channel transmitted from the mobile station is
demodulated and decoded in the base station (step S3818).
[0351] The base station transmits ACK/NACK in accordance with data
channel demodulating and decoding result.
[0352] This international patent application is based on Japanese
Priority Applications No. 2005-105492, No. 2005-174394, No.
2005-241899, No. 2005-317567, No. 2006-031749, filed on Mar. 31,
2005, filed on Jun. 14, 2005, filed on Aug. 23, 2005, filed on Oct.
31, 2005, filed on Feb. 8, 2006, respectively, with the Japanese
Patent Office, the entire contents of which are hereby incorporated
by reference.
INDUSTRIAL APPLICABILITY
[0353] A transmission apparatus, a reception apparatus, a mobile
communications system and a transmission control method according
to an embodiment of the present invention are applicable to a
mobile communications system in which packet communications are
performed.
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