Method and apparatus for transmitting/receiving multiple codewords in SC-FDMA system

Abstract

The present invention relates a method and apparatus for transmitting/receiving data using multiple codewords in a communication system using SC-FDMA (single carrier frequency division multiple access). A transmitter generates the multiple codewords for user data and transmits the generated multiple codewords. A receiver receives the multiple codewords and sequentially performs decoding and SIC (successive interference cancellation) on the received multiple codewords. Therefore, this structure can minimize a PAPR (peak to average power ratio) and considerably reduces interference between symbols in a frequency selective fading environment.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application

Therefore, an output signal s_k(n) of the DFT mapper 150 at an L-point for an n-th transmission time is defined by Equation 2 given below:
s_k(n)=[s_k,0(n),s_k,1(n), . . . ,s_k,L-1(n)].  (Equation 2)

Various methods can be used to map d_k^(m), m=1, 2, . . . M to s_k(n). For example, the following mapping method can be used. When M=L, d_k^(l)(n) is mapped to one of the L elements forming s_k(n). When M=L/P (where P is a positive integer), P elements among Q elements forming d_k^(m) are mapped to P elements among L elements forming s_k(n).

FIGS. 3 and 4 are diagrams illustrating examples of the mapping method performed by the DFT mapper 150 when M=L, L=4, and Q=6. FIG. 3 shows an example of the mapping of one sub-stream to one DFT index, and FIG. 4 shows an example of the mapping of one sub-stream to another DFT index with time. FIGS. 5 and 6 are diagrams illustrating examples of the mapping method performed by the DFT mapper 150 when M=L/2, L=4, and Q=6. In this exemplary embodiment of the present invention, the mapping methods shown in FIGS. 3, 4, 5, and 6 are described, but the present invention is not limited thereto. Various mapping methods other than the mapping methods shown in FIGS. 3, 4, 5, and 6 may be used.

The L-point DFT 160 performs L-point DFT on the output signal s_k(n) of the DFT mapper 150, and outputs a signal x_k(n) that is defined by Equation 3 given below:

$\begin{array}{cc}{x}_k\left(n\right)={\mathrm{Vs}}_k\left(n\right),n=0,1,\dots ,\frac{\mathrm{QM}}{L}-1.& \left(\mathrm{Equation}3\right)\end{array}$

In Equation 3, “V=[v₁ v₂ . . . v_L]” is a DFT matrix, and an element [V]_l,m, which is in an l-th row and an m-th column, is defined by Equation 4 given below:

$\begin{array}{cc}{\left[V\right]}_{l,m}\frac{1}{\sqrt{2\pi L}}{e}^{-j2\pi lm/L}.& \left(\mathrm{Equation}4\right)\end{array}$

Next, the SC-FDMA receiver for a communication system using SC-FDMA according to an exemplary embodiment of the present invention will be described in detail with reference to FIGS. 7 and 8.

FIG. 7 is a diagram illustrating the structure of the SC-FDMA receiver according to the exemplary embodiment of the present invention. The SC-FDMA receiver according to the exemplary embodiment of the present invention performs N-point FFT on a received signal, performs the demapping of a subcarrier to separate user signals, and detects and decodes the separated user signals to estimate each of the user signals.

As shown in FIG. 7, the SC-FDMA receiver according to the exemplary embodiment of the present invention includes an N-point FFT 710, a subcarrier demapper 720, and a plurality of detectors and decoders 730-1 to 730-J. The N-point FFT 710 receives signals through a receiving antenna, performs N-point FFT on the received signals, and inputs the signals subjected to the N-point FFT to the subcarrier demapper 720. The subcarrier demapper 720 performs a subcarrier demapping process on the signals input from the N-point FFT 710 to separate user signals, and inputs the separated user signals to the corresponding detectors and decoders 730-1 to 730-J. The detectors and decoders 730-1 to 7304 detect and decode the user signals input from the subcarrier demapper 720 to estimate the user signals.

FIG. 8 is a diagram illustrating the structure of an SC-FDMA receiver for a user k according to another exemplary embodiment of the present invention. Particularly, FIG. 8 is a detailed diagram illustrating a structure for detecting and decoding signals for an arbitrary user k.

As shown in FIG. 8, the SC-FDMA receiver for the user k according to another exemplary embodiment of the present invention includes an N-point FFT 810, a subcarrier demapper 820, a detector 830, a decoder 840, a CRC (cyclic redundancy checker) 850, a signal regenerator 860, and an SIC 870. Alternatively, the SC-FDMA receiver for the user k according to another exemplary embodiment of the present invention may further include a channel state information generator 880. The N-point FFT 810 and the subcarrier demapper 820 have the same structures as the N-point FFT 710 and the subcarrier demapper 720 shown in FIG. 7, and thus a detailed description thereof will be omitted.

The detector 830 performs a channel estimating process on the user signals input from the subcarrier demapper 820, detects the user signals, and inputs Q detected output signals forming one sub-stream to the decoder 840.

The decoder 840 decodes the Q detected output signals input from the detector 830, and inputs the decoded bits to the CRC 850.

The CRC 850 receives the decoded bits from the decoder 840, and checks the CR (cyclic redundancy) values thereof. When the checked CR value is correct, the CRC 850 considers that signals for one sub-stream are correctly decoded, and notifies the signal regenerator 860 of the fact. On the other hand, when the checked CR value is incorrect, the CRC 850 determines that the signals for one sub-stream are incorrectly decoded, and transmits a retransmission request signal to the SC-FDMA transmitter.

The signal regenerator 860 receives the notification from the CRC 850, regenerates the original transmission signal for one sub-stream, and inputs the regenerated signal to the SIC 870.

The SIC 870 multiplies the transmission signal input from the signal regenerator 860 by a channel value to generate a reception signal for one sub-stream, subtracts a received sub-stream signal from a user reception signal to obtain a modulated user reception signal, and inputs the modulated user reception signal to the detector 830 again to detect other sub-stream signals.

The channel state information generator 880 calculates channel state information values for M sub-streams and feeds back the channel state information values to the SC-FDMA transmitter. In this case, the channel state information values for the M sub-streams of the user k are obtained by calculating the SINR values of the signals detected by the detector 830, considering sequential interference cancellation. Alternatively, the channel state information generator 880 calculates the transmission power P₁, transmission power offset Ω, and data transfer rate R of a first sub-stream, and feeds back the calculated transmission power P₁, transmission power offset Ω, and data transfer rate R of the first sub-stream to the SC-FDMA transmitter.

Next, a receiving method using multiple codewords in a communication system using SC-FDMA according to an exemplary embodiment of the present invention will be described in detail with reference to a flowchart shown in FIG. 9.

The SC-FDMA receiver in the communication system using SC-FDMA performs FFT on a received signal (step S910). In this case, the N-point FFT 810 performs N-point FFT on the signal received through the receiving antenna, and inputs the signals subjected to the N-point FFT to the subcarrier demapper 720.

Then, the subcarrier demapper 820 performs a subcarrier demapping process on the signals output from the N-point FFT 810 to extract user signals (step S920). Specifically, the subcarrier demapper 820 performs the subcarrier demapping process on the signals input from the N-point FFT 810 to separate the user signals, and inputs the separated user signals to the detector 830.

Then, the detector 830 detects the user signals for one sub-stream separated by the subcarrier demapper 820 (step S930). Specifically, the detector 830 detects the user signals input from the subcarrier demapper 820, and inputs Q detected output signals forming one sub-stream to the decoder 840.

Subsequently, decoding is performed using the Q detected output signals forming one sub-stream (step S940). Specifically, the decoder 840 decodes the Q detected output signals input from the detector 830, and inputs the decoded signals to the CRC 850.

Steps S930 and S940 in which signals for an arbitrary user k are detected and decoded will be described in more detail below.

In order to estimate signals for the user k, the detector 830 extracts only the signals for the user k that are input from the subcarrier demapper 820. When the extracted signal for the user k is “r_k(n)”, the extracted signal r_k(n) can be represented by Equation 5 given below:
r_k(n)=H_kVs_k(n)+w_k(n)  (Equation 5)

where “H_k=diag(H_k,0,H_k,1, . . . , H_k,L-1)” indicates a frequency domain channel characteristic for the user k, and “w_k(n)” indicates an AWGN (additive white Gaussian noise) signal having an average of “0” and a variance of “σ_w²”.

The detector 830, the decoder 840, and the SIC 850 are used to separate M sub-streams from the extracted signal r_k(n). It is assumed that decoding is sequentially performed on the M sub-streams in the order of sub-streams 1, 2, . . . , M, for convenience of explanation. However, the present invention is not limited thereto.

First, the detector 830 is used to decode the first sub-stream separated from the extract signal r_k(n). In this exemplary embodiment of the present invention, any type of detector may be used, but an MMSE (minimum mean square error) detector is used in this exemplary embodiment of the present invention for convenience of explanation.

The MMSE detector for finding out an element s_k,l(n), which is an l-th element of s_k(n), from the extracted signal r_k(n) can be represented by Equation 6 given below:

where “v_l” indicates an l-th column vector of a DFT matrix (v),
f_k⁽¹⁾=(H_kH_k^H+σ_w²I_L)⁻¹H_kv_l.  (Equation 6)

When M=L and DFT mapping is performed as shown in FIG. 3, f_k⁽¹⁾ is used to detect the first sub-stream. When DFT mapping is performed as shown in FIG. 5A, f_k⁽¹⁾ and f_k⁽²⁾ are used to detect the first sub-stream. When DFT mapping is performed as shown in FIG. 5B, f_k⁽¹⁾ and f_k⁽³⁾ are used to detect the first sub-stream. In the SC-FDMA transmitter, the MMSE detector corresponding to the first sub-stream is used to perform DFT mapping on the first sub-stream, and the Q detected output signals forming the first sub-stream are decoded.

The decoder 840 determines a transmission signal for the sub-stream using the decoded signal (step S950). The CRC 850 checks the CR value of the signal decoded by the decoder 840. When the CR value is correct, the CRC 850 considers that the signal for the first sub-stream is correctly decoded, and notifies the signal regenerator 860 of the fact. On the other hand, when the CR value is incorrect as the check result, the CRC 850 considers that the signal for the first sub-stream is incorrectly decoded, and transmits a retransmission request signal to the SC-FDMA transmitter.

When the signal for the first sub-stream is correctly decoded, the signal regenerator 860 regenerates the original transmission signal for the first sub-stream and inputs the regenerated signal to the SIC 870.

The SIC 870 multiplies the transmission signal generated by the signal regenerator 860 by a channel value to obtain a reception signal for the sub-stream (step S960). Specifically, the SIC 870 multiplies the transmission signal input from the signal regenerator 860 by a channel value to generate a reception signal for the first sub-stream, and subtracts the reception signal generated by the signal regenerator 860 from a detected input signal r_k(n) to generate a modulated detection input signal r_k⁽¹⁾(n) (step S970). That is, the SIC 870 subtracts the reception signal input from the signal regenerator 860 from the extracted signal r_k(n) to generate a modulated signal r_k⁽¹⁾(n), and inputs the modulated signal r_k⁽¹⁾(n) to the detector 830 again.

Then, the same method as that used for the first sub-stream (i.e., the processes from step S930 to step S970) is performed on r_k⁽¹⁾(n) to decode the second sub-stream. This method (i.e., processes from step S930 to step S970) is similarly performed on the sub-streams (3, 4, . . . , M) to decode the sub-streams, thereby estimating the sub-stream (2, 3, . . . , M).

That is, it is checked that the processes from step S930 to step 5970 are repeated up to the M-th sub-stream (step S980). As the check result, when the processes are not performed up to the M-th sub-stream, the processes are repeated from step S930. The processes from step S930 to step S970 are repeatedly performed on the sub-streams (2, 3, . . . , M) to estimate the sub-streams (2, 3, . . . , M).

Another embodiment of the present invention provides a method of controlling the transfer rate and the transmission power of each sub-stream using feedback information output from the SC-FDMA receiver in the SC-FDMA transmitter, which makes it possible to improve a data transfer rate. In addition, according to this embodiment of the present invention, the SC-FDMA receiver feeds back a post-detection SINR for each sub-stream to the SC-FDMA transmitter, and the SC-FDMA transmitter independently performs channel coding and QAM mapping on each sub-stream, which makes it possible to improve an SIC gain and a data transfer rate by the channel state adaptive transmission.

Next, a method of feeding back channel state information items CQI₁ to CQI_M for M sub-streams to the SC-FDMA transmitter will be described.

As described above, the SC-FDMA receiver estimates channels for M sub-streams, calculates a post-detection SINR for each sub-stream in consideration of SIC, and feeds back the calculated SINR for each sub-stream to the SC-FDMA transmitter.

That is, when the signal r_k(n) for the user k is extracted from the subcarrier demapper 820 and the sub-streams (1, 2, . . . , M) are removed from the extracted signal to obtain a modulated signal, the modulated signal is defined as “r_k^(m)(n)” and it is defined that “r_k(n)=r_k⁽⁰⁾(n)”. The SINR value of the signal obtained by the detector 830 may be used as the channel state information value. When the detector 830 detects a modified signal r_k^(m-1)(n) for the M-th sub-stream to obtain a signal, a channel state information value for the M-th sub-stream of the user k can be obtained by calculating the SINR value of the obtained signal. The SINR is a post-detection SINR in consideration of SIC. In this way, the channel state information values for M sub-streams are calculated, and the calculated values are fed back to the SC-FDMA transmitter.

Then, the SC-FDMA transmitter determines a data transfer rate for each sub-stream using the feedback information (i.e., channel state information) from the SC-FDMA receiver.

In the DFT mapping method, different DFT indexes are mapped to one sub-stream.

However, when DFT indexes are mapped to the corresponding sub-streams, the difference between the post-detection SINRs of adjacent sub-streams is substantially constant. That is, when the post-detection SINR of a j-th sub-stream is referred to as “SINR_j”, the sub-streams (1, 2, . . . , M−1) satisfy Equation 7 given below:
SINR_j+1≈SINR_j+Δ.  (Equation 7)

Therefore, when the DFT indexes are mapped to the corresponding sub-streams, the SC-FDMA receiver may feed back an SINR offset Δ between the post-detection SINR of the j-th sub-stream (SINR) and the post-detection SINR of the first sub-stream.

That is, as described above, the SC-FDMA receiver estimates channels for M sub-streams, calculates the post-detection SINR of the first sub-stream (SINR₁), calculates the SINR offset Δ between the sub-streams, and feeds back the calculated post-detection SINR of the first sub-stream (SINR₁) and the calculated SINR offset Δ to the SC-FDMA transmitter.

In this case, the SC-FDMA transmitter calculates an SINR for each sub-stream using the information fed back from the SC-FDMA receiver, and the SINR of the j-th sub-stream is estimated by Equation 8 given below.
SINR_j≈SINR₁+(j−1)Δ.  (Equation 8)

In Equation 8, “SINR₁” indicates the post-detection SINR of the j-th sub-stream in consideration of sequential interference cancellation, and the SC-FDMA transmitter determines a data transfer rate according to the calculated SINR for each sub-stream and transmits data at the determined data transfer rate.

In this embodiment, a channel feedback method when all of the sub-streams are transmitted with the same transmission power has been described. Next, the structure in which SC-FDMA transmitter transmits the sub-streams at the same data transfer rate but with different transmission powers will be described.

The SC-FDMA receiver feeds back two values to the SC-FDMA transmitter. One of the two values is a data transfer rate (or SINR) applied to all of the sub-streams, and the other value is the transmission power offset Ω.

That is, as described above, the SC-FDMA receiver estimates channels for M sub-streams, calculates the transmission power P₁, transmission power offset Ω, and data transfer rate R of the first sub-stream, and feeds back the calculated transmission power P₁, transmission power offset Ω, and data transfer rate R of the first sub-stream to the SC-FDMA transmitter.

The SC-FDMA transmitter performs channel coding and QAM symbol mapping on each sub-stream using the data transfer rate (or SINR) from the SC-FDMA receiver, and calculates power required to transmit each sub-stream using the transmission power offset Ω. The SC-FDMA transmitter performs channel coding and QAM mapping using the data transfer rate R that is fed back from the SC-FDMA receiver, and determines power required to transmit each sub-stream, on the basis of the transmission power P₁ and transmission power offset Ω of the first sub-stream that are fed back from the SC-FDMA receiver, by using Equation 9 given below:
P_j=P₁−(j−1)Ω,  (Equation 9)

where “P_j” indicates power required to transmit the j-th sub-stream.

In this way, when the sub-streams are transmitted by different powers, it is possible to considerably reduce the reception error rate.

The components described in the exemplary embodiments of the present invention may be achieved by hardware components including at least one DSP (digital signal processor), a processor, a controller, an ASIC (application specific integrated circuit), a programmable logic element such as an FPGA (field programmable gate array), other electronic devices, and combinations thereof. At least some of the functions or the processes described in the exemplary embodiments of the present invention may be achieved by software, and the software may be recorded on a recording medium. The components, the functions, and the processes described in the exemplary embodiments of the present invention may be achieved by a combination of hardware and software.

While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

According to the above-described exemplary embodiments of the present invention, it is possible to minimize PAPR in a communication system using SC-FDMA, and considerably reduce interference between symbols in a frequency selective fading environment.

Claims

1. A communication methodof transmitting symbols in a transmitter, the method comprising:

preparing a plurality of sub-streams including generating a first sub-stream stream and a second sub-stream stream;

independently performing first channel coding on each of the first stream to generate a first channel coded stream and performing second channel coding on the second sub-streams stream to generate a second channel coded stream, wherein the first channel coding and the second channel coding are performed according to different coding schemes;

mapping the first and second channel coded sub-streams streams to modulation symbols, wherein different channel coded sub-streams streams are mapped to different modulation symbols;

generating single carrier frequency division multiple access (SC-FDMA) symbols from the modulation symbols, one of the SC-FDMA symbols being generated by using at least a part of the modulation symbols from the first sub-stream channel coded stream and a part of the modulation symbols from the second sub-stream channel coded stream; and

transmitting the SC-FDMA symbols to a receiver.

2. The method of claim 1, wherein generating the SC-FDMA symbols comprises:

transforming the modulation symbols;

mapping the transformed symbols to subcarriers; and

generating the SC-FDMA symbols from the symbols mapped to the subcarriers.

3. The method of claim 1, wherein a transfer rate of the first sub-stream and a transfer rate of the second sub-stream are differently determined.

4. The method of claim 3 1, further comprising receiving an offset for determining the transfer rate of the first sub-stream and the transfer rate of the second sub-stream from the receiver wherein a coding rate of the first channel coding is different from a coding rate of the second channel coding.

5. The method of claim 1, further comprising receiving feedback information from the receiver; and

determining transfer rates of the sub-streams coding rates of the first channel coding and the second channel coding based on the feedback information.

6. A method of receiving a signal in a receiver, the method comprising: receiving single carrier frequency division multiple access (SC-FDMA) symbols from a transmitter; and

extracting a plurality of sub-streams including a first sub-stream and a second sub-stream from the SC-FDMA symbols,

wherein the SC-FDMA symbols are generated, by the transmitter, by independently performing channel coding on each of the first and second sub-streams, mapping the channel coded sub-streams to modulation symbols, generating the SC-FDMA symbols from the modulation symbols,

wherein different channel coded sub-streams are mapped to different modulation symbols, and wherein one of the SC-FDMA symbols are generated by using at least part of the modulation symbols from the first sub-stream and part of the modulation symbols from the second sub-stream.

7. The method of claim 6, wherein the modulation symbols are transformed, the transformed symbols are mapped to subcarriers, and the SC-FDMA symbols are generated from the symbols mapped to the subcarriers, by the transmitter.

8. The method of claim 6, wherein a transfer rate of the first sub-stream and a transfer rate of the second sub-stream are differently determined.

9. The method of claim 8, further comprising transmitting an offset for determining the transfer rate of the first sub-stream and the transfer rate of the second sub-stream.

10. The method of claim 6, further comprising transmitting feedback information for determining transfer rates of the sub-streams to the transmitter.

11. A transmitter comprising:

a demultiplexer configured to prepare a plurality of sub-streams including a first sub-stream and a second sub-stream;

a plurality of encoders configured to independently perform channel coding on each of the first and second sub-streams;

a mapper configured to map the channel coded sub-streams to modulation symbols, wherein different channel coded sub-streams are mapped to different modulation symbols; and

a generator configured to generate single carrier frequency division multiple access (SC-FDMA) symbols, to be transmitted to a receiver, from the modulation symbols, one of the SC-FDMA symbols being generated by using at least part of the modulation symbols from the first sub-stream and part of the modulation symbols from the second sub-stream.

12. The transmitter of claim 11, wherein the generator comprises:

a first transformer configured to transform the modulation symbols;

a subcarrier mapper configured to map the transformed symbols to subcarriers; and

a second transformer configured to generate the SC-FDMA symbols from the symbols mapped to the subcarriers.

13. The transmitter of claim 11, wherein a transfer rate of the first sub-stream and a transfer rate of the second sub-stream are differently determined.

14. The transmitter of claim 13, further comprising a rate controller configured to receive an offset for determining the transfer rate of the first sub-stream and the transfer rate of the second sub-stream from the receiver.

15. The transmitter of claim 11, further comprising a rate controller configured to receive feedback information from the receiver, and determine transfer rates of the sub-streams based on the feedback information.

16. A receiver comprising:

a receiver configured to receive single carrier frequency division multiple access (SC-FDMA) symbols from a transmitter; and

a decoder configured to extract a plurality of sub-streams including a first sub-stream and a second sub-stream from the SC-FDMA symbols,

wherein the SC-FDMA symbols are generated, by the transmitter, by independently performing channel coding on each of the first and second sub-streams, mapping the channel coded sub-streams to modulation symbols, generating the SC-FDMA symbols from the modulation symbols,

wherein different channel coded sub-streams are mapped to different modulation symbols, and

wherein one of the SC-FDMA symbols are generated by using at least part of the modulation symbols from the first sub-stream and part of the modulation symbols from the second sub-stream.

17. The receiver of claim 16, wherein the modulation symbols are transformed, the transformed symbols are mapped to subcarriers, and the SC-FDMA symbols are generated from the symbols mapped to the subcarriers, by the transmitter.

18. The receiver of claim 16, wherein a transfer rate of the first sub-stream and a transfer rate of the second sub-stream are differently determined.

19. The receiver of claim 18, further comprising an information generator configured to transmit an offset for determining the transfer rate of the first sub-stream and the transfer rate of the second sub-stream.

20. The receiver of claim 16, further comprising an information generator configured to transmit feedback information for determining transfer rates of the sub-streams to the transmitter.

21. The communication method of claim 1, wherein the one of the SC-FDMA symbols is transmitted from a single antenna.

22. A communication apparatus, comprising:

a circuitry configured to:

cause the communication apparatus to generate a first stream and a second stream;

cause the communication apparatus to perform first channel coding on the first stream to generate a first channel coded stream and perform second channel coding on the second stream to generate a second channel coded stream, wherein the first channel coding and the second channel coding are performed according to different coding schemes;

cause the communication apparatus to map the first and second channel coded streams to modulation symbols, wherein different channel coded streams are mapped to different modulation symbols;

cause the communication apparatus to generate single carrier frequency division multiple access (SC-FDMA) symbols from the modulation symbols, one of the SC-FDMA symbols being generated by using at least a part of the modulation symbols from the first channel coded stream and a part of the modulation symbols from the second channel coded stream; and

cause the communication apparatus to transmit the SC-FDMA symbols to a receiver.

23. The communication apparatus of claim 22, wherein the circuitry is configured to, when generating the SC-FDMA symbols:

cause the communication apparatus to map the modulation symbols to subcarriers; and

cause the communication apparatus to generate the SC-FDMA symbols from the subcarriers.

24. The communication apparatus of claim 22, wherein a coding rate of the first channel coding is different from a coding rate of the second channel coding.

25. The communication apparatus of claim 22, wherein the circuitry is further configured to cause the communication apparatus to receive feedback information from the receiver; and

determine coding rates of the first channel coding and the second channel coding based on the feedback information.

26. The communication apparatus of claim 22, wherein the one of the SC-FDMA symbols is transmitted from a single antenna.

27. A communication apparatus, comprising:

a circuitry configured to:

cause the communication apparatus to receive single carrier frequency division multiple access (SC-FDMA) symbols from a transmitter;

cause the communication apparatus to generate modulation symbols from the SC-FDMA symbols;

cause the communication apparatus to generate a first channel coded stream and a second channel coded stream from the modulation symbols, wherein at least a part of the first channel coded stream and at least a part of the second channel coded stream are generated from one of the SC-FDMA symbols;

and cause the communication apparatus to perform first channel decoding on the first channel coded stream to generate a first stream and perform second channel decoding on the second channel coded stream to generate a second stream, wherein the first channel decoding and the second channel decoding are performed according to different decoding schemes.

28. The communication apparatus of claim 27, wherein a coding rate of the first channel decoding is different from a coding rate of the second channel decoding.

29. The communication apparatus of claim 27, wherein the circuitry is further configured to:

cause the communication apparatus to generate feedback information based on the first channel decoding and the second channel decoding; and

cause the communication apparatus to transmit the feedback information to the transmitter.

30. The communication apparatus of claim 27, wherein the one of the SC-FDMA symbols is transmitted from a single antenna of the transmitter.

31. A communication device for a transmitter, the communication device comprising:

a circuitry configured to:

cause the transmitter to generate a first stream and a second stream;

cause the transmitter to perform first channel coding on the first stream to generate a first channel coded stream and perform second channel coding on the second stream to generate a second channel coded stream, wherein the first channel coding and the second channel coding are performed according to different coding schemes;

cause the transmitter to map the first and second channel coded streams to modulation symbols, wherein different channel coded streams are mapped to different modulation symbols;

cause the transmitter to generate single carrier frequency division multiple access (SC-FDMA) symbols from the modulation symbols, one of the SC-FDMA symbols being generated by using at least a part of the modulation symbols from the first channel coded stream and a part of the modulation symbols from the second channel coded stream; and

cause the transmitter to transmit the SC-FDMA symbols to a receiver.

32. The communication device of claim 31, wherein the circuitry is configured to, when generating the SC-FDMA symbols:

cause the transmitter to map the modulation symbols to subcarriers; and

cause the transmitter to generate the SC-FDMA symbols from the subcarriers.

33. The communication device of claim 31, wherein a coding rate of the first channel coding is different from a coding rate of the second channel coding.

34. The communication device of claim 31, wherein the circuitry is further configured to cause the transmitter to receive feedback information from the receiver; and

determine coding rates of the first channel coding and the second channel coding based on the feedback information.

35. The communication device of claim 31, wherein the one of the SC-FDMA symbols is transmitted from a single antenna.