U.S. patent number RE45,902 [Application Number 14/106,602] was granted by the patent office on 2016-02-23 for method of transmitting data using repetition coding.
This patent grant is currently assigned to LG Electronics Inc.. The grantee listed for this patent is LG ELECTRONICS INC.. Invention is credited to Jin Young Chun, Bin Chul Ihm, Sunam Kim, Hyun Soo Ko, Sung Ho Park.
United States Patent |
RE45,902 |
Chun , et al. |
February 23, 2016 |
**Please see images for:
( Certificate of Correction ) ** |
Method of transmitting data using repetition coding
Abstract
A method of transmitting data in a wireless communication system
is provided. The method includes generating duplicate data by using
repetition coding, the duplicate data being the same as original
data, shifting the phase of the duplicate data, and transmitting
the original data and the phase-shifted duplicate data. The
duplicate data is mapped to a modulation symbol having a different
size or phase as that of the original data, thus to reduce the PAPR
unlike the general repetition coding.
Inventors: |
Chun; Jin Young (Anyang-si,
KR), Ihm; Bin Chul (Anyang-si, KR), Ko;
Hyun Soo (Anyang-si, KR), Park; Sung Ho
(Anyang-si, KR), Kim; Sunam (Anyang-si,
KR) |
Applicant: |
Name |
City |
State |
Country |
Type |
LG ELECTRONICS INC. |
Seoul |
N/A |
KR |
|
|
Assignee: |
LG Electronics Inc. (Seoul,
KR)
|
Family
ID: |
40693171 |
Appl.
No.: |
14/106,602 |
Filed: |
December 13, 2013 |
PCT
Filed: |
September 03, 2008 |
PCT No.: |
PCT/KR2008/005164 |
371(c)(1),(2),(4) Date: |
March 02, 2010 |
PCT
Pub. No.: |
WO2009/031801 |
PCT
Pub. Date: |
March 12, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
12676132 |
Sep 3, 2008 |
8391380 |
Mar 5, 2013 |
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Foreign Application Priority Data
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Sep 3, 2007 [KR] |
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10-2007-0088830 |
Oct 4, 2007 [KR] |
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10-2007-0099954 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L
27/2621 (20130101); H04L 1/0003 (20130101); H04L
27/2615 (20130101); H04L 1/08 (20130101); H04L
27/2614 (20130101) |
Current International
Class: |
H04K
1/10 (20060101); H04L 1/08 (20060101); H04L
1/00 (20060101) |
Field of
Search: |
;375/267,295,260 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2433397 |
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Jun 2007 |
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EP |
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2433397 |
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Jun 2007 |
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GB |
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2004/100501 |
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Nov 2004 |
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WO |
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2004/100501 |
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Nov 2004 |
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WO |
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2005/101718 |
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Oct 2005 |
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WO |
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2006/050131 |
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May 2006 |
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WO |
|
Primary Examiner: Nguyen; Linh M
Attorney, Agent or Firm: Dentons US LLP
Claims
The invention claimed is:
1. A method of transmitting data in a wireless communication
system, the method comprising: .Iadd.receiving information about a
number of times of repetition coding;.Iaddend. generating duplicate
data by using repetition coding, the duplicate data being the same
as original data; changing .[.the.]. .Iadd.a .Iaddend.phase of the
duplicate data; allocating the original data and the phase-changed
duplicate data to the subcarriers in a same orthogonal frequency
division multiplexing (OFDM) symbol; and transmitting the original
data and the phase-changed duplicate data, wherein the original
data are transmitted through a first frequency band being comprised
of contiguous subcarriers and the phase-changed duplicate data are
transmitted through a second frequency band being comprised of
contiguous subcarriers, the first frequency band and the second
frequency band are different frequency bands in .Iadd.a
.Iaddend.frequency domain.Iadd., wherein a number of the duplicate
data is determined by the number of times of the repetition
coding.Iaddend..
2. The method of claim 1, wherein the phase of the duplicate data
are changed by a unitary matrix `C` which is
.times..times..times..times. ##EQU00003##
3. The method of claim 1, wherein the phase of the duplicate data
are changed by a CAZAC (Constant Amplitude Zero Auto-Correlation)
sequence.
4. A method of transmitting data in a wireless communication
system, the method comprising: generating duplicate data which is
the same as original data by using .Iadd.a .Iaddend.repetition
coding; changing .[.the.]. .Iadd.a .Iaddend.size and .[.the.].
.Iadd.a .Iaddend.phase of the duplicate data; allocating the
original data and the duplicate data with the changed size and
phase to the subcarriers in a same orthogonal frequency division
multiplexing (OFDM) symbol; and transmitting the original data and
the duplicate data with the changed size and phase.
5. The method of claim 4, further comprising: after the size and
the phase of the duplicate data are changed, performing discrete
fourier transform (DFT) and inverse fast fourier transform (IFFT)
in sequence.
6. A data transmitter comprising: a data processing unit to perform
repetition coding for original data to generate duplicate
data.Iadd., wherein the number of duplicated data is determined by
a number of times of the repetition coding.Iaddend.; a data
changing unit to change .[.the.]. .Iadd.a .Iaddend.phase of the
duplicate data; and a subcarrier allocating unit to map the
original data and the phase-changed duplicate data to subcarriers
in a same orthogonal frequency division multiplexing (OFDM) symbol,
wherein the original data are transmitted through a first frequency
band being comprised of contiguous subcarriers and the
phase-changed duplicate data are transmitted through a second
frequency band being comprised of contiguous subcarriers, the first
frequency band and the second frequency band are different
frequency bands in .Iadd.a .Iaddend.frequency domain.
Description
This application is a .Iadd.reissue of, and claims the benefit of,
U.S. Pat. No. 8,391,380; however, more than one reissue application
has been filed for U.S. Pat. No. 8,391,380. The reissue
applications are Ser. No. 14/106,602 (the present application) and
Ser. No. 14/337,931, both of which are divisional reissues of U.S.
Pat. No. 8,391,380. U.S. Pat. No. 8,391,380 issued on Mar. 5, 2013,
which is a .Iaddend.35 U.S.C. .sctn.371 National Stage entry of
International Application No. PCT/KR2008/005164, filed on Sep. 3,
2008, and claims .[.priority to.]. .Iadd.the benefit of
.Iaddend.Korean Application No. 10-2007-0088830, filed on Sep. 3,
2007 and Korean Application No. 10-2007-0099954, filed on Oct. 4,
2007 each of which is hereby incorporated by reference in its
entirety as if fully set forth herein.
TECHNICAL FIELD
The present invention relates to wireless communication and, more
particularly, to a method of transmitting data using repetition
coding.
BACKGROUND ART
Research on a 4G (4th Generation) mobile communication system, a
next-generation communication system, is actively ongoing to
provide services with various QoS (Quality of Service) with a
transfer rate of about 10 Mbps to users. The 4G mobile
communication system is being standardized to aim at cooperatively
operating a wired communication network and a wireless
communication network and providing integrated services, beyond
simple wireless communication services such as mobile communication
systems of a previous generation.
As a large capacity communication system, which may process and
transmit various information such as images, radio data, or the
like, beyond voice-centered services, is requested, development of
a technique allowing transmission of large capacity data similar to
the capacity of the wired communication network to the wireless
communication network is on demand.
Thus, a proper channel coding method that can improve a system
performance by minimizing a loss of information and increasing the
efficiency of system transmission is recognized and admitted as an
essential factor. In general, in order to reduce information loss,
the reliability of a system is increased by using various channel
codings depending on the properties of channels, one of which is a
repetition coding. In the repetition coding, original data to be
transmitted is repeated to generate a plurality of same data as the
original data. Because the duplicate data, which is the same as the
original data, are generated and transmitted together with the
original data, the probability of a transmission error can be
reduced.
In general, in an OFDM (Orthogonal Frequency Division Multiplexing)
system, spectrums of sub-channels overlap with each other while
maintaining cross-orthogonality, having good spectrum efficiency,
and because OFDM modulation/demodulation is implemented by IFFT
(Inverse Fast Fourier Transform) and FFT (Fast Fourier Transform),
a modulating/demodulating unit can be effectively implemented
digitally and resistant to a frequency selective fading or a
narrowband interference.
Despite such advantages, the OFDM system is disadvantageous in that
it has a high peak-to-average power ratio (PAPR). The OFDM
transmits data by using many carriers, so a final OFDM signal has
the size of amplitude tantamount to the sum of amplitude sizes of
the respective carriers, having a severe change width of amplitude,
and if the phases of the carriers correspond, a quite large value
can be obtained. In particular, in case of using the repetition
coding in the OFDM system, the same data is repeatedly transmitted,
and for uplink, a resource allocation region does not have a square
shape, making it difficult to lower the PAPR and possibly degrading
the performance of the system.
Thus, in order to data by using repetition coding, a method for
lowering the PAPR is required.
DISCLOSURE OF INVENTION
Technical Problem
An object of the present invention is to provide a method of
transmitting data using repetition coding capable of reducing a
PAPR by dividing data obtained through repetition coding and
mapping the divided data to different modulation symbols.
Technical Solution
According to an embodiment of the invention, a method of
transmitting data in a wireless communication system is provided.
The method includes generating duplicate data by using repetition
coding, the duplicate data being the same as original data,
shifting the phase of the duplicate data, and transmitting the
original data and the phase-shifted duplicate data.
According to another embodiment of the invention, a method of
transmitting data in a wireless communication system is provided.
The method includes generating duplicate data which is the same as
original data by using repetition coding, changing the size and the
phase of the duplicate data, and transmitting the original data and
the duplicate data with the changed size and phase.
According to still another embodiment of the invention, a data
transmitter is provided. The data transmitter includes a data
processing unit to perform repetition coding for original data to
generate duplicate data, a data changing unit to shift the phase of
the duplicate data, and a subcarrier allocating unit to map the
original data and the phase-shifted duplicate data to a
subcarrier.
Advantageous Effects
In the present invention, because the original data, the result of
repeated coding, and duplicate data are discriminated and the
duplicate data is mapped to a modulation symbol having a different
size or phase as that of the original data and transmitted, to thus
reducing the PAPR unlike the general repetition coding.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a wireless communication system.
FIG. 2 shows an example of a frame structure.
FIG. 3 is a schematic block diagram of a transmitter according to
an embodiment of the present invention.
FIG. 4 shows a method of repetition coding according to another
embodiment of the present invention.
FIG. 5 shows a method of repetition coding according to an
embodiment of the present invention.
FIG. 6 is a graph comparatively showing PAPRs in case of using the
repetition coding according to Table 1 to Table 4.
MODE FOR THE INVENTION
Hereinafter, exemplary embodiments of the present invention will be
described in detail with reference to the accompanying drawings so
that this disclosure can be through and complete, and will fully
convey the concept of the invention to those skilled in the
art.
FIG. 1 shows a wireless communication system. The wireless
communication system can be widely deployed to provide a variety of
communication services, such as voices, packet data, etc.
Referring to FIG. 1, the wireless communication system includes a
base station (BS) 20 and at least one user equipment (UE) 10. The
BS 20 is generally a fixed station that communicates with the UE 10
and may be referred to as another terminology, such as a node-B, a
base transceiver system (BTS), an access point, etc. There are one
or more cells within the coverage of the BS 20. The UE 10 may be
fixed or mobile, and may be referred to as another terminology,
such as a mobile station (MS), a user terminal (UT), a subscriber
station (SS), a wireless device, etc.
A downlink represents a communication link from the BS 20 to the UE
10, and an uplink represents a communication link from the UE 10 to
the BS 20. In the downlink, a transmitter may be a part of the BS
20, and a receiver may be a part of the UE 10. In the uplink, the
transmitter may be a part of the UE 10, and the receiver may be a
part of the BS 20.
Downlink and uplink transmissions can be made using different
multiple access schemes. For example, orthogonal frequency division
multiple access (OFDMA) may be used for downlink transmission, and
single carrier-frequency division multiple access (SC-FDMA) may be
used for uplink transmission.
There is no restriction on the multiple access scheme used in the
wireless communication system. The multiple access scheme may be
based on code division multiple access (CDMA), time division
multiple access (TDMA), frequency division multiple access (FDMA),
single-carrier FDMA (SC-FDMA), orthogonal frequency division
multiple access (OFDMA), or other well-known modulation schemes. In
these modulation schemes, signals received from multiple users are
demodulated to increase capacity of the communication system.
FIG. 2 shows an example of a frame structure. The frame refers to a
data sequence during a fixed time period used by physical
specifications, and it may be an OFDMA frame.
With reference to FIG. 2, the frame includes a downlink frame and
an uplink frame. Time division duplex (TDD) refers to a method in
which uplink and downlink transmissions take place in the same
frequency bandwidth but occur at each different time. The downlink
frame temporally goes ahead of the uplink frame. The downlink frame
includes a preamble, a frame control header (FCH), a DL
(Downlink)-MAP, a UL (Uplink)-MAP, a downlink burst region. The
uplink frame includes an uplink burst region.
A guard time for discriminating the uplink frame and the downlink
frame is inserted to a middle portion of the frame (i.e., between
the downlink frame and the uplink frame), and to a final portion
(after the uplink frame). A transmit/receive gap (TTG) refers to a
gap between the downlink burst and the subsequent uplink burst. A
receive/transmit transition gap (RTG) refers to a gap between the
uplink burst and a subsequent downlink burst.
The preamble is used for initial synchronization, cell search,
frequency offset, and channel estimation between a base station and
a mobile station. The FCH includes the length of a DL-MAP message
and repetition coding information used for the DL-MAP message. The
DL-MAP is a region on which the DL-MAP message is transmitted. The
DL-MAP message defines an access of a downlink channel The DL-MAP
message includes a configuration change count of a DCD (Downlink
Channel Descriptor) and a base station ID (Identifier).
The DCD describes a downlink burst profile applied to a current
map. The downlink burst profile refers to characteristics of a
downlink physical channel, and the DCD is periodically transmitted
by the base station via a DCD message. The UL-MAP is a region on
which a UL-MAP message is transmitted. The UL-MAP message defines
an access of an uplink channel The UL-MAP message includes a
configuration change count of a UCD (Uplink Channel Descriptor) and
a valid start time of uplink allocation defined by the UL-MAP.
The UCD describes an uplink burst profile. The uplink burst profile
refers to characteristics of an uplink physical channel, and the
UCD is periodically transmitted by the base station via a UCD
message.
A portion of the uplink frame includes a fast feedback region. The
fast feedback region is allocated for a faster uplink transmission
than general uplink data, and a CQI, ACK/NACK signal, or the like,
may be included in the fast feedback region. The fast feedback
region may be positioned anywhere in the link frame and not
necessarily limited to the illustrated position or size.
Hereinafter, a slot is a minimum possible data allocation unit and
defined as time and a subchannel. In the uplink, subcarrier may
include a plurality of tiles. The subcarrier may include six tiles
and in the uplink, one burst may include three OFDM symbols and one
subcarrier.
In a PUSC (Partial Usage of Subchannels) permutation, each tile may
include four contiguous subcarriers on three OFDM symbols. In an
optional PUSC permutation, each time may include three contiguous
subcarriers on three OFDM symbols. The tiles included in the
subcarriers are distributed to every band so as to be disposed.
A bin includes nine contiguous subcarriers on an OFDM symbol. A
band refers to a group of four rows of the bin, and AMC (Adaptive
Modulation and Coding) subcarrier includes six contiguous bins in
the same band.
The FCH including information regarding repetition coding is merely
one example of being applied to the system having the frame
structure as shown in FIG. 2. Namely, the FCH may be included in a
different channel in a different frame structure without being
limited to such a frame structure as shown in FIG. 2. Hereinafter,
an apparatus and method for transmitting data by using repetition
coding according to the present invention will be described.
FIG. 3 is a schematic block diagram of a transmitter according to
an embodiment of the present invention.
With reference to FIG. 3, the transmitter 100 includes a data
processing unit 110, a data changing unit 120, and a subcarrier
allocating unit 130. The transmitter 100 may be a part of a base
station (BS). The BS refers to a fixed station communicating with a
terminal, and may be called a node-B, a base transceiver system
(BTS), an access point (AP), or other terms.
The data processing unit 110 repeatedly codes inputted information
bits to generate duplicate information bits which are the same as
information bits, and maps the information bits and the duplicate
information bits to data symbols expressing positions on a signal
constellation. Hereinafter, the symbol level data generated by
mapping the information bits is called original data and the symbol
level data generated by mapping the duplicate information bits is
called duplicate data.
The number of duplicate data differs according to the determined
number of times of repetition in a system. The information about
the number of times of repetition coding is signaled by the
transmitter to a receiver via the FCH in the system having such a
frame structure as shown in FIG. 2. There is no limitation in the
number of times of repetition, and the number of times of
repetition may be set two times, four times or six times depending
on systems.
The data processing unit 110 discriminates the original data and
the duplicate data and sends the original data to the subcarrier
allocating unit 130 and the duplicate data to the data changing
unit 120.
The data changing unit 120 changes the phase or the size or the
phase and size of the duplicate data and transmits the same to the
subcarrier allocating unit 130. Hereinafter, the original data is
S.sub.N and the duplicate data having a phase which has been
shifted by .theta. by the data changing unit 120 and has a size of
k times is ke.sup.j.theta.S.sub.N. .theta. is a phase difference of
the original data and the duplicate data with respect to the same
information bits, and `k` is a ratio of the size of the duplicate
data to the original data. Let e.sup.j.theta. be .alpha. for
convenience's sake. The duplicate data that has passed through the
data changing unit 120 would be k.alpha.S.sub.N. Here, if `k` is 1,
it means that only the phase of the original data has been shifted,
and if `.alpha.` is 1, it means that only the size of the original
data has been changed. Because `k` and `.alpha.` are variables, if
the two variables change independently, the duplicate data may be
data obtained as both the phase and the size of the original data
have been all changed.
The data changing unit 120 may change only the size of the original
data to generate duplicate data, or change only the phase of the
original data to generate duplicate data, or change both the size
and the phase of the original data to generate duplicate data. A
PAPR (Peak-to-Average Power Ratio) can be reduced by
differentiating the phase or the size of the original data and the
duplicate data and transmitting data.
The subcarrier allocating unit 130 appropriately allocates (or
maps) inputted original data and duplicate data to subcarriers and
multiples them according to users. The subcarrier allocating unit
130 may use various multiplexing schemes such as OFDM as well as
SC-FDMA.
In case of using the repetition coding, in general, the same data
signal is repeated, so the PAPR is increased. In this case,
however, if the original data and the duplicate data are repeatedly
coded by differentiating their size or phase, undergo DFT (Discrete
Fourier Transform) or IDFT (Inverse Discrete Fourier Transform) and
IFFT (Inverse Fast Fourier Transform) (in the form of SC FDMA), and
are transmitted, a gain in terms of PAPR can be obtained.
In the SC-FDMA scheme, the subcarrier allocating unit 130 may
perform DFT on the contiguous subcarrier, a frequency band used for
transmitting the original data or the duplicate data. The data,
which has undergone the DFT process with respect to the contiguous
subcarrier on a single OFDM symbol, is converted into a signal of
frequency domain. The subcarrier allocating unit 130 performs IFFT
on the signal which has undergone the DFT process over the entire
frequency band to convert it into a signal of a time domain.
In case of using the OFDMA scheme, unlike the SC-FDMA scheme, the
transmitter can immediately perform IFFT on the subcarrier without
performing DFT process to convert it into a signal of a time
domain. In this manner, each OFDM symbol may undergo DFT spreading
and then IFFT to maintain low PAPR characteristics.
An example of a simple method for differentiating the size or the
phase may be an application of unitary matrix to original data.
Namely, N-dimension unitary matrix may be multiplied to the
original data to obtain one original data and the (N-1) number of
duplicate data.
Equation 1 shows an example of the method of generating duplicate
data by using the unitary matrix. The matrix `C` is a unitary
matrix.
.times..times..times..times..times. ##EQU00001##
For one example, if four original data to which the matrix `C` is
applied is S.sub.0,S.sub.1,S.sub.2,S.sub.3, one duplicate data
S.sub.0,S.sub.1,S.sub.2,S.sub.3, which is the same as the original
data, is generated by a first row 1,1,1,1, and the other three
remaining duplicate data are
S.sub.0,jS.sub.1,-S.sub.2,-jS.sub.3,S.sub.0,-S.sub.1,
S.sub.2,-S.sub.3, and S.sub.0,-jS.sub.1,-S.sub.2,jS.sub.3,
respectively.
For another example of a simple method of differentiating the size
or the phase, a Zadoff-Chu (ZC) CAZAC (Constant Amplitude Zero
Auto-Correlation) sequence may be applied. As for the ZC CAZAC
sequence, one of CAZAC sequences, if `N` is the length of a CAZAC
sequence, a positive integer, and an index `M` is a prime number
(`M` is a natural number of `N` or smaller, and `M` and `N` are
prime numbers with each other) relatively compared with `N`, the
kth element of the Mth CAZAC sequence may be expressed by equation
2 shown below:
.times..function..times..times..times..pi..function..times..times..time-
s..times..times..times..times..times..times..times..times..times..times..f-
unction..times..pi..times..times..times..times..times..times..times..times-
..times..times..times. ##EQU00002##
This is merely an example, and any other sequences having good
correlation characteristics may be applied. For different
terminals, channels may be discriminated by applying ZC CAZAC
sequences each having a different circular shift value.
The unitary matrix `C` or the CAZAC sequence used for generating
the duplicate data by changing the size or the phase of the
original data as described above is merely an example. Namely, the
unitary matrix used for generating the duplicate data may be a
3.times.3 matrix, a 5.times.5 matrix, or the like, besides
4.times.4 matrix. Also, the size `k` may be 2, 3, or else, not
necessarily `1`, and any matrixes may be used so long as they can
maintain orthogonality between duplicate data.
The method of repetition coding will be described in detail. In
order to clarify the description, if repetition is `2`, the size of
k=1 will be taken as an example.
FIG. 4 shows a method of repetition coding according to another
embodiment of the present invention.
With reference to FIG. 4, the repetition coding method includes
repeating information bits in units of small data. Namely,
according to this repetition coding method, the results of
repetition coding have such a form that duplicate data is
distributively disposed between original data in view of radio
resource domain (time domain or frequency domain). Accordingly, one
duplicate data is added per original data, like
S.sub.0,.alpha..sub.0S.sub.0,S.sub.1,.alpha..sub.1S.sub.1,S.sub.2,.alpha.-
.sub.2S.sub.2, . . . , S.sub.N,.alpha..sub.NS.sub.N. Here, the
phase difference .theta. between the original data and the
duplicate data may be variably set to 0, .pi./2, .pi./4, .pi./6,
etc., besides .pi..
FIG. 5 shows a method of repetition coding according to an
embodiment of the present invention.
With reference to FIG. 5, the repetition coding method includes
repeating information bits in units of burst. Namely, according to
this method, the results of repetition coding have such a form that
original data and duplicate data are locally gather together, in
view of radio resource domain (time domain or frequency domain).
Accordingly, a set of duplicate data is added to the end of a set
of original data, like S.sub.0, S.sub.1, S.sub.2, . . . ,
S.sub.N,.alpha..sub.0S.sub.0,.alpha..sub.1S.sub.1,.alpha..sub.2S.sub.2,
. . . , .alpha..sub.NS.sub.N. Here, the phase difference .theta.
between the original data and the duplicate data may be variably
set to 0, .pi./2, .pi./4, .pi./6, etc., besides .pi..
The method of repetition coding may be performed variably in
addition to those methods as shown in FIGS. 4 and 5.
A method of allocating original data and duplicate data to each
subcarrier will now be described. Radio resources may be allocated
to the original data and the duplicate data generated according to
the method of FIG. 4 or the method of FIG. 5 by using one of a time
axis and a frequency axis as a preferential reference. Here, it is
assumed that the size (k) of the duplicate data is 1.
Table 1 shows the case of the repetition coding as shown in FIG. 4,
in which when .alpha..sub.0=.alpha..sub.1= . . . =.alpha..sub.N=-1
(namely, when the phase difference .theta. is .pi.), the original
data and the duplicate data are distributively disposed in the
physical radio resource domain (time domain or frequency domain)
and subcarriers are allocated. Namely, the results of the
repetition coding are
S.sub.0,-S.sub.0,S.sub.1,-S.sub.1,S.sub.2,-S.sub.2, . . . ,
S.sub.N,-S.sub.N.
TABLE-US-00001 TABLE 1 OFDM symbol index subcarrier index #1 #2 . .
. #1 S.sub.0 S.sub.1 . . . #2 -S.sub.0 -S.sub.1 . . . #3 S.sub.10
S.sub.11 . . . #4 -S.sub.10 -S.sub.11 . . . #5 S.sub.20 S.sub.21 .
. . #6 -S.sub.20 -S.sub.21 . . . #7 S.sub.30 S.sub.31 . . . #8
-S.sub.30 -S.sub.31 . . . . . . . . . . . . . . .
With reference to Table 1, S.sub.0 and -S.sub.0 are mapped to
subcarriers #1 and #2 on an OFDM symbol #1. S.sub.1 and -S.sub.1
are mapped to subcarriers #1 and #2 on an OFDM symbol #2. In the
same manner, S.sub.9 and -S.sub.9 are mapped to subcarriers #1 and
#2 on an OFDM symbol #9. In the same manner, S.sub.10 and -S.sub.10
are mapped to subcarriers #3 and #4 on an OFDM symbol #1. The
original data and the duplicate data are mapped to the respective
subcarriers on the other remaining OFDM symbols in the same
manner.
Table 2 shows the case of the repetition coding as shown in FIG. 5,
in which when .alpha..sub.0=.alpha..sub.1= . . . =.alpha..sub.N=-1
(namely, when the phase difference .theta. is .pi.), original data
and duplicate data are locally gather together in the physical
radio resource domain (time domain or frequency domain) and
subcarriers are allocated. Namely, the results of the repetition
coding are S.sub.0,S.sub.1,S.sub.2, . . . ,
S.sub.N,-S.sub.0,-S.sub.1,-S.sub.2, . . . , -S.sub.N.
TABLE-US-00002 TABLE 2 OFDM symbol index subcarrier index #1 #2 . .
. #1 S.sub.0 S.sub.1 . . . #2 S.sub.10 S.sub.11 . . . #3 S.sub.20
S.sub.21 . . . . . . . . . . . . . . . #k -S.sub.0 -S.sub.1 . . .
#k + 1 -S.sub.10 -S.sub.11 . . . #k + 2 -S.sub.20 -S.sub.21 . .
.
When information bits are repeatedly coded in units of burst data,
radio resources are allocated such that duplicate data is allocated
starting from a position where allocation of original data is
finished.
With reference to Table 2, with respect to the original data, OFDM
symbols #1 to #9 are first allocated in the subcarrier #1, and the
OFDM symbols #1 to #9 are then allocated in the subcarrier #2.
Resource allocation for the duplicate data starts from a position
where resource allocation for the original data is finished. With
respect to the duplicate data, the OFDM symbols #1 to #9 are first
allocated in the subcarrier #k, and the OFDM symbols #1 to #9 are
then allocated in the subcarrier #k+1.
Table 3 shows the case of repetition coding as shown in FIG. 4, in
which when .alpha..sub.0=.alpha..sub.1= . . . =.alpha..sub.N=1
(namely, when the phase difference .theta. is 0), the original data
and the duplicate data are distributively disposed in the physical
radio resource domain (time domain or frequency domain) and
subcarriers are allocated. Namely, the results of the repetition
coding are S.sub.0,S.sub.0,S.sub.1,S.sub.1,S.sub.2,S.sub.2, . . . ,
S.sub.N,S.sub.N.
TABLE-US-00003 TABLE 3 OFDM symbol index subcarrier index #1 #2 . .
. #1 S.sub.0 S.sub.1 . . . #2 S.sub.0 S.sub.1 . . . #3 S.sub.10
S.sub.11 . . . #4 S.sub.10 S.sub.11 . . . #5 S.sub.20 S.sub.21 . .
. #6 S.sub.20 S.sub.21 . . . #7 S.sub.30 S.sub.31 . . . #8 S.sub.30
S.sub.31 . . . . . . . . . . . . . . .
With reference to Table 3, unlike the case of Table 1, the phase
difference .theta. is 0, a signal has original data and duplicate
data which have the same phase. The order of resource allocation is
the same as that of Table 1.
Table 4 shows the case of repetition coding as shown in FIG. 5, in
which in which when .alpha..sub.0=.alpha..sub.1= . . .
=.alpha..sub.N=-1 (namely, when the phase difference .theta. is 0),
original data and duplicate data are locally gather together in the
physical radio resource domain (time domain or frequency domain)
and subcarriers are allocated. Namely, the results of the
repetition coding are S.sub.0,S.sub.1,S.sub.2, . . . ,
S.sub.N,S.sub.0,S.sub.1,S.sub.2, . . . , S.sub.N.
TABLE-US-00004 TABLE 4 OFDM symbol index subcarrier index #1 #2 . .
. #1 S.sub.0 S.sub.1 . . . #2 S.sub.10 S.sub.11 . . . #3 S.sub.20
S.sub.21 . . . . . . . . . . . . . . . #k S.sub.0 S.sub.1 . . . #k
+ 1 S.sub.10 S.sub.11 . . . #k + 2 S.sub.20 S.sub.21 . . . . . . .
. . . . . . . .
With reference to Table 4, unlike the case of Table 2, the phase
difference is 0, and a signal has original data and duplicate data
which have the same phase. The order or resource allocation is the
same as that of Table 2.
FIG. 6 is a graph comparatively showing PAPRs in case of using the
repetition coding according to Table 1 to Table 4, in which a
horizontal axis indicates the size of PAPRs in SC-FDMA (Single
Carrier-FDMA) employing 24 DFT (Discrete Fourier Transform) by
decibel (dB), and a vertical axis indicates a CDF (Cumulative
Distribution Function) capacity of PAPRs. For comparison, a PAPR in
the general OFDMA is also shown.
With reference to FIG. 6, (1) shows the case of Table 1, (2) shows
the case of Table 2, (3) shows the case of Table 3, (4) shows the
case of Table 4, and (5) shows the case of using the related art
repetition coding technique.
As shown in the graph, it is noted that the case (1) has a
remarkably low PAPR, and the cases (1) to (4) have lower PAPRs than
that of the case (5). Namely, by discriminating the original data
and the duplicate data, the results of the repetition coding,
mapping the duplicate data to a modulation symbol having a
different phase from that of the original data, and transmitting
data, the PAPR can be lowered unlike the case of the general
repetition coding.
All functions described above may be performed by a processor such
as a microprocessor, a controller, a microcontroller, and an
application specific integrated circuit (ASIC) according to
software or program code for performing the functions. The program
code may be designed, developed, and implemented on the basis of
the descriptions of the present invention, and this is well known
to those skilled in the art.
While the present invention has been particularly shown and
described with reference to exemplary embodiments thereof, it will
be understood by those skilled in the art that various changes in
form and details may be made therein without departing from the
spirit and scope of the invention as defined by the appended
claims. The exemplary embodiments should be considered in
descriptive sense only and not for purposes of limitation.
Therefore, the scope of the invention is defined not by the
detailed description of the invention but by the appended claims,
and all differences within the scope will be construed as being
included in the present invention.
* * * * *