WO2007099853A1

WO2007099853A1 - Wireless communication device and re-sending data generating method

Info

Publication number: WO2007099853A1
Application number: PCT/JP2007/053303
Authority: WO
Inventors: Xiaohong Yu; Xiaoming She; Jifeng Li
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 2006-02-24
Filing date: 2007-02-22
Publication date: 2007-09-07
Also published as: CN101026440A

Abstract

In a wireless communication device, an S/P converting unit (401) converts transmitting data to parallel ones, a DFT unit (402) carries out an N point DFT for the parallel data to transform time-domain data to frequency-domain ones (sub-carrier data), a sub-carrier selecting unit (403) selects data from the frequency-domain data under control of a sub-carrier selecting control unit (409), a mapping unit (404) carries out mapping of the selected data on the sub-carrier, an IDFT unit (405) transforms the mapping-subjected data to the time-domain data by a point IDFT, a CP adding unit (406) adds a CP to the time-domain data input from the IDFT unit (405), a P/S conversing unit (407) converts data to serial ones, a wireless-transmitting unit (408) carries out wireless-transmission processing for the serial data, and an antenna (412) transmits the data subjected to the wireless-transmission processing.

Description

Specification

Wireless communication apparatus and retransmission data generation method

Technical field

TECHNICAL FIELD [0001] The present invention relates to a radio communication apparatus, and more particularly to a radio communication apparatus that performs retransmission and a retransmission data generation method.

Background art

[0002] In conventional mobile communication, it is necessary to perform channel code correction and error correction due to instability and temporal change of a radio channel due to a radio communication environment. The commonly used hybrid repeat request (HARQ) technique is a technique that performs error detection and error correction by combining automatic repeat request (ARQ) and forward error correction (FEC). In normal HARQ, redundant (IR) bits are increased, that is, only a part of the original data is transmitted during retransmission, and the retransmission data and the original data are combined on the receiving side.

[0003] The method of combining retransmission data and original data on the receiving side includes, for example, equal gain combining (EG C), maximum ratio combining (MRC), and minimum mean square error combining (MMSEC). The equal gain synthesis method does not perform error correction for channel distortion because the output is obtained by adding only the gain equal to the signal envelope of each subchannel. In the least mean square error synthesis method, the error in the estimated value of the data signal needs to be orthogonal to the baseband part of the received signal, so when the signal is weak, the gain is reduced so that the noise is not amplified, the signal is strong, In some cases, the gain is proportional to the inverse of the signal envelope. The maximum ratio combining method weights each diversity subcarrier so that the SIR (Signal to Interference Ratio) of the output signal is maximized. When the maximum ratio combining method is used, the gain of each combining group is proportional to the signal amplitude, and the SIR of the combined signal is the sum of the SIRs of each subcarrier before combining, so a relatively good error correction effect can be obtained. .

[0004] With the development of the communication industry, many new technologies have been developed, such as OFDM (Orthogonal Frequency Division Multiplexing), DFT-¾ OFDM (Discrete Fourier Transform-Spread Orthogonal Frequency Division Multiplexing), and the like. Currently, OFDM technology is attracting attention for multipath fading and interference due to high spectrum utilization. Due to its strength, it is expected to become a core technology for future high-speed mobile communications.

FIG. 1 is a block diagram showing a configuration of an OFDM system using conventional HARQ.

In FIG. 1, on the transmission side, transmission data is processed by an encoding unit 101, a modulation unit 102, and an SZP conversion unit 103. When it is determined that there is a retransmission request and retransmission is performed using IR, that is, it is common to select some frequency domain data for retransmission. When selecting retransmission data, there are a method of selecting retransmission subcarriers based on feedback information 108 and a method of selecting retransmission subcarriers based on prior settings. The frequency domain retransmission data selected by subcarrier selection section 104 is converted to time domain data by IFFT section 105, processed by CP adding section 106 and PZS conversion section 107, and transmitted from the antenna. . On the receiving side, when the received data is processed by the SZP conversion unit 109 and the CP removal unit 110 and converted to frequency domain data by the FFT unit 111 and determined to be retransmission data, the data synthesis unit Synthesized according to 112. Next, the original data is restored by the processing of the PZS conversion unit 113, the demodulation unit 114, and the decoding unit 115. In this way, when the partial data in the frequency domain is transmitted even at the time of retransmission with respect to the original data in the frequency domain, the error rate characteristics of the partial data to be retransmitted are improved, but are not retransmitted. There is a problem that data error rate characteristics are not improved.

[0006] Further, in the OFDM system, when a part of data is selected and retransmitted, there is a problem that the peak-to-average power ratio (PAPR) becomes high, particularly in a radio communication system. This problem becomes significant in the uplink. Much of the research on uplink to solve this problem is concentrated on SC-FDMA (Single Carrier-Frequency Division Multiplexing) systems, and DFT-SOFDM is one example.

[0007] FIG. 2 is a diagram showing a configuration of a DFT-SOFDM system using conventional HARQ.

In FIG. 2, on the transmission side, transmission data (time domain data) is converted into a parallel signal by the SZP conversion unit 201. When it is determined that there is a retransmission request and retransmission is performed using IR, the data selection unit 202 selects retransmission data based on the feedback information 208 or selects retransmission data according to a predetermined setting. The selected data is converted into retransmission data in the frequency domain by the N-point DFT of the DFT unit 203 and mapped to the subcarrier by the subcarrier mapping unit 204. In addition, IDFT unit 205 M It is converted into retransmission data in the time domain by the IDFT, processed by the CP adding unit 206 and the PZS conversion unit 207, and transmitted from the antenna. On the receiving side, the process opposite to that on the transmitting side is performed. That is, on the receiving side, the received data is converted into parallel data by the SZP conversion unit 209, the CP is removed by the CP removal unit 210, and the received data in the frequency domain is converted by the M-point DFT of the DFT unit 211. The subcarrier demapping unit 212 demaps the data, and the IDFT unit 213 converts the data into time domain data using the N-point IDFT. When it is determined that the data is retransmitted data, the data combining unit 214 combines the retransmitted data with the original data, and the PZS conversion unit 215 converts the data into serial data to restore the original data.

FIG. 3 is a retransmission flow diagram of a DFT-SOFDM system using conventional HARQ.

In FIG. 3, first, in step 301 (S301), it is determined whether or not the received data in the time domain is retransmission data. If it is determined that the received data is retransmission data (YES in S301), based on the feedback information. Then, part of the data in the time domain is selected as retransmission data (S302). The selected retransmission data or transmission data (if NO in S301) is converted to frequency domain data by N-point DFT (S303), and the converted retransmission data is mapped to a subcarrier (S304). Next, the retransmission data mapped to the subcarrier is converted into data in the time domain by M point IDFT (S305), and the converted data is transmitted (S306). The received time domain data is converted to frequency domain data by M-point DFT (S307), demapped (S308), and then converted to time domain data by N-point IDFT (S309). Next, it is determined whether the data is retransmission data (S310). If it is determined that the data is retransmission data (YES in S310), the retransmission data is combined with the previously received data (S311). It is detected whether there is an error in the synthesized data (S312). If there is no error (YES in S312), the process is terminated. If an error is detected (NO in S312), it is determined whether the number of retransmissions exceeds the maximum number of retransmissions (S313). If the maximum number of retransmissions is not exceeded (NO in S313), a retransmission request is transmitted. If the maximum number of retransmissions is exceeded (YES in S313), the process ends.

[0009] The DFT-SOFDM system as described above can solve the problem of high PAPR due to the method of selecting and retransmitting some data by DFT and IDFT of the transmission data. Suitable for transmission. Disclosure of the invention

Problems to be solved by the invention

[0010] However, in the conventional OFDM system or DFT-SOFDM system as described above, when transmitting original data in the time domain (that is, when the transmission data is time domain data), even when retransmitting, the time domain If the retransmission data is transmitted in, and the original data is transmitted in the frequency domain (that is, if the transmission data is frequency domain data), the retransmission data is also transmitted in the frequency domain during retransmission. Then, the data is restored by combining the original data and the retransmission data on the receiving side. Such a retransmission method improves the error rate characteristics of retransmission data, but has the problem that the error rate characteristics of data that is not retransmitted are not improved.

An object of the present invention is to provide a radio communication apparatus and a retransmission data generation method that can improve the error rate characteristics of the entire data and can further increase the throughput of the system.

Means for solving the problem

[0012] The wireless communication apparatus of the present invention includes: transmission data generating means for generating time domain or frequency domain transmission data; and retransmission data generating means for generating retransmission data in a different area from the transmission data area. The structure to comprise is taken.

The invention's effect

[0013] According to the present invention, it is possible to improve the error rate characteristics of the entire data by retransmitting the data in a region different from the original data. Brief Description of Drawings

[0014] [FIG. 1] A block diagram showing a configuration of a conventional OFDM system using HARQ.

[Figure 2] Block diagram showing the configuration of a conventional DFT-SOFDM system using HARQ

[Fig.3] Retransmission flow diagram of DFT-SOFDM system using conventional HARQ

FIG. 4 is a block diagram showing a configuration of a DFT-SOFDM system according to Embodiment 1 of the present invention.

FIG. 5 is a retransmission flow diagram according to Embodiment 1 of the present invention. FIG. 6 is a flowchart showing a subcarrier selection method according to Embodiment 1 of the present invention.

FIG. 7 is a diagram showing a puncture matrix according to Embodiment 1 of the present invention.

FIG. 8 is a flowchart of subcarrier selection processing at the time of retransmission according to Embodiment 1 of the present invention.

FIG. 9 is a diagram showing simulation results according to Embodiment 1 of the present invention.

FIG. 10 is a block diagram showing a configuration of an OFDM system according to Embodiment 2 of the present invention.

FIG. 11 is a retransmission flow diagram of an OFDM system according to Embodiment 2 of the present invention.

FIG. 12 is a flowchart of subcarrier selection processing at the time of retransmission according to Embodiment 2 of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiment described here is for the purpose of explaining the present invention rather than limiting the present invention. Further, the present invention is not limited to each numerical value described in the present specification, and those numerical values may be appropriately changed as necessary. In the present specification, the present invention will be described by taking an OFDM system and a DFT-SOF DM system as examples. The present invention can be applied to a wireless communication system that transmits and retransmits data in the frequency domain or time domain.

First, the principle of the present invention will be described.

[0017] In order to improve the error rate characteristics of the entire received data, it is necessary to transmit as much data as possible at the time of retransmission. Therefore, in the present invention, in the DFT-SOFDM system or OFDM system, data in a region different from the original data is selected and retransmitted. For example, in the DFT-SOFDM system, frequency domain data is selected and retransmitted, and in the OFDM system, time domain data is selected and retransmitted.

[0018] Specifically, in the DFT-SOFDM system, the original data is time-domain data, and the time-domain data is converted into frequency-domain data by DFT. If the original data in the time domain is x (n) (n = 0, 1, 2, ···, N— 1), the frequency domain data X (k) ( k = 0, 1, 2,..., N— 1) is obtained.

[Number 1]

N-i

(k) = ^ x (n) e- ^{j2mk lN} = 0,1,2, ..., 1 1… (1) X (k) transformed to the frequency domain as shown in equation (1) X (n) (n = 0, 1, 2 ..., N— 1) is included. That is, each frequency domain subcarrier obtained by DFT includes data information of all data substreams in the time domain. In the DFT—SOFDM system, data in the time domain, that is, x (n) (n = a, ---, b, a, b≡ (0, 1, 2..., N— 1 )) To select and retransmit a part of the retransmitted data x (n) (n = a, ---, b , a, b≡ (0, 1, 2..., N-1)) only, and the error rate characteristics of the data that is not retransmitted are not improved. In contrast, in the present invention, frequency domain data, that is, X (k) (k = 0, 1, 2,..., N−l) force is also selected and retransmitted with some subcarriers. Therefore, data information of all data substreams in the time domain is included in each of some of the retransmitted subcarriers. Therefore, in the present invention, by combining the original data and the retransmission data on the receiving side, it is possible to improve the error rate characteristics of all the data even though only a part of the subcarriers are retransmitted. The system throughput can be increased.

Further, in the OFDM system, the original data X (k) (k = 0, 1, 2,..., N−1) in the frequency domain is converted into time domain data x by IFFT shown in Equation (2). (n) Converted to (n = 0, 1, 2,..., N— 1).

[Equation 2] x (n) "= 0,1,2, ..., -1… (2)

As shown in Equation (2), X (k) (k = 0, 1, 2,..., N−1) is included in each of x (n) converted into the time domain. That is, information on all subcarriers in the frequency domain is included in each time domain data. In the OFDM system, when selecting and retransmitting part of the frequency domain data (data before IFFT conversion) as before, the original data and the retransmitted data are combined on the receiving side. Therefore, the error rate characteristics of only part of the retransmitted data are improved, and the error rate characteristics of the part of the data that is not retransmitted are not improved. In contrast, in the present invention, time-domain data (data after IFFT conversion), that is, x (n) (n = 0, 1, 2,..., N—l) force is selected. Therefore, information on all subcarriers in the frequency domain is included in each part of the retransmitted data. Information is included. Therefore, in the present invention, by combining the original data and the retransmission data on the receiving side, it is possible to improve the error rate characteristics of all data even though only a part of the data substream is retransmitted. And further increase the system throughput.

Next, a method for selecting retransmission data will be described.

[0022] In the present invention, when selecting some subcarriers or some data substreams as retransmission data, there are methods such as selecting in order, selecting at random, or selecting at equal intervals. For example, to select some subcarriers in order, select the first partial subcarrier when performing the first retransmission, and select the next part of the first when performing the second retransmission. Subcarriers are selected. When selecting some subcarriers at equal intervals, select the subcarriers at regular intervals when performing the first retransmission, and repeat the same intervals when performing the second retransmission. Select another subcarrier. When some subcarriers are selected at random, subcarriers are selected at random every time retransmission is performed.

[0023] Note that the number of subcarriers to be selected decreases as the number of retransmissions increases. Also, subcarriers are adaptively selected according to the channel conditions. You can also select subcarriers according to predetermined rules.

[0024] When adaptively selecting subcarriers according to channel conditions, a plurality of puncture matrices corresponding to each channel condition and the number of retransmissions are set in advance. By determining an appropriate puncture matrix based on the channel condition and the number of retransmissions at the time of retransmission, the subcarrier can be used for retransmission data, and retransmission can be performed by selecting the corresponding subcarrier. .

[Embodiment 1]

In Embodiment 1, the case where the present invention is applied to a DFT-SOFDM system will be described.

FIG. 4 is a diagram showing a configuration of the DFT-SOFDM system according to the present embodiment.

In wireless transmission device 100, SZP conversion section 401 converts the transmission data into parallel data and outputs it to DFT section 402. [0028] DFT section 402 performs N-point DFT on the parallel-converted data, converts the time domain data into frequency domain data (subcarrier data), and sends it to subcarrier selection section 403. Output.

[0029] Subcarrier selection section 403 selects data from frequency domain data input from DFT section 402 in accordance with control from subcarrier selection control section 409 described later.

[0030] Mapping section 404 maps the selected data to subcarriers, and provides IDFT section 4

Output to 05.

[0031] IDFT section 405 converts the mapped data into time-domain data using M-point IDFT and outputs the data to CP adding section 406.

[0032] CP adding section 406 adds a CP to the time-domain data input from IDFT section 405.

[0033] PZS conversion section 407 converts the parallel data input from CP-equipped card section 406 into serial data, and outputs the serial data to radio transmission section 408.

The wireless transmission unit 408 performs wireless transmission processing on serial data.

The antenna 412 transmits the data subjected to the wireless transmission process to the wireless reception device 200. In addition, the antenna 412 receives feedback information from the radio reception device 200 and outputs the feedback information to the radio reception unit 411.

Radio reception section 411 performs radio reception processing on the received signal and outputs the result to feedback information extraction section 410.

[0037] Feedback information extraction section 410 extracts feedback information indicating the error status, channel status, etc. fed back from radio receiving apparatus 200, and outputs it to subcarrier selection control section 409.

[0038] Subcarrier selection control section 409 determines whether or not the transmission data is retransmission data based on the feedback information, and determines the subcarrier selection method in subcarrier selection section 403 according to the determination result. Control. Details of the subcarrier selection method will be described later.

In radio receiving apparatus 200, antenna 421 receives data transmitted from radio transmitting apparatus 100 and outputs the data to radio receiving section 422. In addition, the fee from the wireless transmitter 433 The back information is transmitted to the wireless transmission device 100.

[0040] Radio reception section 422 performs radio reception processing of the received data and outputs the result to SZP conversion section 423.

[0041] SZP conversion section 423 converts serial data input from radio reception section 422 into parallel data, and outputs the parallel data to CP removal section 424.

The CP removal unit 424 also removes the CP from the parallel received data force input from the SZP conversion unit 423 and outputs the result to the DFT unit 425.

[0043] DFT section 425 performs M-point DFT on the received data input from CP removing section 424, converts the received data into frequency domain received data, and outputs the result to demapping section 426.

The demapping unit 426 demaps the reception data converted into the frequency domain, and outputs it to the data synthesis unit 427.

[0045] The data synthesis unit 427 performs the demapping unit according to the control from the data synthesis control unit 431.

The frequency domain received data input from 426 is combined with the original data in the time domain to generate synthesized data, which is output to IDFT section 428.

[0046] IDFT section 428 performs N points I on the combined data input from data combining section 427.

DFT is performed to convert it into time domain composite data, which is output to the PZS converter 429.

[0047] PZS conversion section 429 converts the combined data in the time domain input from IDFT section 428 into serial data, generates restoration data, and outputs it to error detection section 430.

[0048] Error detection section 430 detects whether or not there is an error in the restored data input from PZS conversion section 429, and outputs the detection result to feedback information generation section 432.

[0049] Feedback information generation section 432 generates feedback information based on the detection result from error detection section 430 and channel information from a channel estimation section (not shown). Then, the feedback information generation unit 432 outputs the generated feedback information to the data composition control unit 431 and the wireless transmission unit 433.

[0050] Based on the feedback information from the feedback information generation unit 432, the data composition control unit 431 determines whether or not the received data is retransmission data. If it is determined that the data is retransmission data, the data synthesis control unit 431 outputs an instruction to synthesize the received data and the original data to the data synthesis unit 427. On the other hand, if it is determined that the data is not retransmitted data, The control unit 431 outputs an instruction not to synthesize received data to the data synthesis unit 427.

[0051] Radio transmission section 433 performs feedback information radio transmission processing and outputs the result to antenna 421.

FIG. 5 is a retransmission flow diagram according to the present embodiment. In radio transmitting apparatus 100, transmission data in the time domain is converted into transmission data in the frequency domain by the N-point DFT of DFT section 402 (S501). The subcarrier selection control unit 409 determines whether or not the transmission data in this frequency domain is a retransmission data (S502). If it is determined that the data is retransmission data (YES in S502), subcarrier selection section 403 uses some subcarriers as retransmission data according to the selection method instructed from subcarrier selection control section 409 based on feedback information. Select (S503). Next, the retransmission data is mapped to the subcarrier by the mapping unit 404 (S504), and the retransmission data is converted into retransmission data in the time domain by the M point IDFT of the IDFT unit 405 (S505). CP is added to the retransmission data, wireless transmission processing is performed, and retransmission data in the time domain is transmitted from antenna 412 (S506). Radio receiving apparatus 200 receives data transmitted from radio transmitting apparatus 100, performs radio reception processing, and removes CP. The received data is converted into received data in the frequency domain by the M point DFT of the DFT unit 425 (S507). The demapping unit 426 demaps the received data mapped to the subcarrier (S508). Next, the data composition control unit 431 determines whether or not the received data is retransmission data (S509). If it is determined that the data is retransmission data (YES in S509), the received data is combined with the original data to generate combined data (S510). Synthetic data force The NFT IDFT of the DFT unit 428 converts the data into time domain synthetic data and generates restored data (S511). The error detection unit 430 detects whether or not there is an error in the restored data (S512). If an error is detected (NO in S512), the feedback information generation unit 432 determines whether the number of retransmissions exceeds the maximum number of retransmissions (S513), and if the maximum number of retransmissions is not exceeded! / In S513, NO), feedback information is generated and transmitted to the wireless transmission device 100. If no error is detected in the received data in step S512, that is, if the data is correctly received, the process ends. Also, if an error is detected in the received data in step S512, if it is determined in step S513 that the number of retransmissions exceeds the maximum number of retransmissions, the process ends To do.

[0053] Next, a subcarrier selection method will be described in detail. FIG. 6 shows a subcarrier selection method according to the present embodiment.

[0054] The first selection method is a method of selecting in order. Select all subcarriers when sending for the first time. When performing the first retransmission, select a predetermined number of subcarriers in order, and when performing the second retransmission, select a predetermined number of subcarriers in order from the subcarrier selected last time, The same applies thereafter.

[0055] The second selection method is a method of selecting at equal intervals. Select all subcarriers when sending for the first time. When the first retransmission is performed, a predetermined number of subcarriers are selected at equal intervals. When the second retransmission is performed, a predetermined number of subcarriers that are different from the previously selected subcarrier are selected at equal intervals. Is the same.

[0056] The third selection method is a random selection method. Select all subcarriers when sending for the first time. When retransmission is performed, a predetermined number of subcarriers are randomly selected.

[0057] Subcarrier selection control section 409 determines a selection method to be used at the time of retransmission based on PAPR by each of the above three selection methods.

[0058] When the number of subcarriers to be selected is small (for example, when the number of subcarriers is less than half of the total number of subcarriers), the PAPR value at the time of retransmission is the PAPR value at the time of initial transmission in any of the above three selection methods. Lower than the value. In the first selection method (selection method in order), the power that has a slight effect on the PAPR value depending on the selection start position Basically, all subcarriers that are related to the number of subcarriers to be selected are selected. The PAPR value is always lower than the case. In the second selection method (selection at equal intervals) and the third selection method (random selection method), if the number of subcarriers to be selected is less than half of the total number of subcarriers, all subcarriers are If the PAPR value is lower than when selecting, but the number of subcarriers to be selected is more than half of the total number of subcarriers, the PAPR value is higher than when selecting all subcarriers.

[0059] Therefore, when the number of subcarriers to be selected is less than half of the total number of subcarriers, any of the three selection methods may be used. On the other hand, when the number of subcarriers to be selected is more than half of the total number of subcarriers, subcarrier selection control section 409 uses the first selection method ( Decide to use the method of selecting in order.

[0060] In the above three selection methods, the number of subcarriers to be selected, that is, the number of subcarriers to be retransmitted may be decreased as the number of retransmissions increases.

[0061] Also, subcarrier selection control section 409 may select subcarriers appropriately according to the channel conditions and the number of retransmissions. The adaptive selection method is described below.

FIG. 7 is a diagram showing a puncture matrix according to the present embodiment. Figure 7 shows an example of a puncture matrix (also called a subcarrier selection matrix) for one frame of data. Assuming that the data length of one frame is K and the number of subcarriers is N, the matrix H is one frame at the time of initial transmission.

NXK

Indicates the subcarrier selection status of the data for the frame, where h is k-th nk in the frame

The selection status of the n-th subcarrier (n-th row) of the symbol (k-th column) is shown. Subcarriers selected for transmission are represented by “1”, and subcarriers not selected are represented by “0”. Therefore, the larger the number of “1” in the matrix, the more subcarriers selected for transmission.

[0063] Since all subcarriers are selected at the time of initial transmission, all elements of the matrix are "1".

[0064] On the other hand, since some subcarriers are selected and retransmitted during retransmission, the puncture matrix used for the first retransmission and the second retransmission are used so that all subcarriers are selected equally. Differentiate from the puncture procession. Specifically, `` 1 '' in the puncture matrix used for the first retransmission is set to `` 0 '' in the puncture matrix used for the second retransmission, and `` 0 '' in the puncture matrix used for the first retransmission is Set to “1” in the puncture matrix used for the second retransmission. As a result, a different subcarrier is selected for each retransmission, and the transmission diversity effect can be improved.

[0065] Furthermore, subcarriers that are as different as possible are selected for each symbol (different column) in the same puncture matrix. For example, when the first and second subcarriers are selected for symbol 1 (first column), the third and fourth subcarriers are selected for symbol 2. This makes it possible to select all subcarriers at least once for each symbol at the time of performing the maximum number of retransmissions (Nth retransmission). As described above, a good transmission diversity effect can be obtained by uniformly distributing “1” and “0” of the puncture matrix.

[0067] A puncture matrix as described above may be set in advance, and at the time of retransmission, a subcarrier may be selected according to the corresponding puncture matrix based on the number of retransmissions and the channel status included in the feedback information. For example, as shown in FIG. 7, the channel status is divided into classes 1 to n in order of goodness, and the number of “1” s in the puncture matrix is increased as the channel status class becomes higher (that is, as the channel status becomes worse). . In other words, the worse the channel conditions during retransmission, the greater the number of subcarriers selected.

For example, in the case of channel status 2, that is, when the channel status is good, the numbers of “1” and “0” in the puncture matrix are almost the same. In other words, half of the data is retransmitted during retransmission. On the other hand, in the case of channel condition 3, the number of “1” s in the puncture matrix is greater than the number of “0” s. That is, more than half of the data is retransmitted at the time of retransmission. Also, in the case of channel condition n, that is, when the channel condition is very bad, the number of “1” s in the puncture matrix is much larger than the number of “0”. That is, almost all data is retransmitted at the time of retransmission.

Further, as described above, in order to obtain the transmission diversity effect, the positions of “1” and “0” in the respective matrices H 1, H 2,...

1 2 n

Note that the numbers of “1” and “0” may be different in different matrices.

[0070] [Table 1]

In Table 1 above, the vertical direction indicates the channel condition class, and the channel condition is very good (SNR> S1), good (S2 <SNR≤S1), normal (S3 <SNR≤S2), bad (S4 <SNR) ≤S3), very bad (SNR≤S4). Classification criteria include SNR value or Use information such as Doppler frequency shift. In Table 1, the horizontal direction indicates the number of retransmissions.

FIG. 8 is a flowchart of subcarrier selection processing at the time of retransmission according to the present embodiment. FIG. 8 is a diagram showing details of step S503 in the flowchart of FIG. The subcarrier selection control unit 409 determines a corresponding puncture matrix with reference to Table 1 based on the channel status fed back and the number of retransmissions (S801), and outputs it to the subcarrier selection unit 403. The subcarrier selection unit 403 selects a subcarrier according to the puncture matrix instructed from the subcarrier selection control unit 409 (S802).

[0072] As described above, since a puncture matrix corresponding to each combination of the channel status and the number of retransmissions is set in advance, it is possible to adaptively select a subcarrier at the time of retransmission based on feedback information, which is favorable. As a result, it is possible to improve the system throughput.

FIG. 9 is a diagram showing a simulation result according to the present embodiment. In this simulation, the conventional retransmission in the time domain is compared with the retransmission in the frequency domain according to the present embodiment. On the sending side, a 32-point DFT and a 512-point IDFT are used. In addition, the maximum number of retransmissions is two, and the data that is retransmitted each time is half of the original data. That is, at the time of retransmission, 16 subcarriers are selected and retransmitted. Here, the first selection method (a method of selecting subcarriers in order) is used. The maximum ratio combining is used on the receiving side. As shown in FIG. 9, when the throughput is the same, according to the present embodiment, a gain of about 1 to 1.8 dB is obtained in the SNR value as compared with the conventional case.

[0074] Thus, according to the present embodiment, the error rate characteristics of all data are improved and the throughput is improved by retransmitting part of the data in a region different from the original data. be able to.

[0075] (Embodiment 2)

In Embodiment 2, a case where the present invention is applied to an OFDM system will be described.

FIG. 10 is a diagram showing a configuration of the OFDM system according to the present embodiment.

In radio transmitting apparatus 300, encoding section 1001 encodes transmission data and outputs the encoded transmission data to modulation section 1002. Modulation section 1002 modulates the encoded data and outputs it to SZP conversion section 1003.

[0079] SZP conversion section 1003 converts the modulated data into a parallel serial power and outputs the parallel data to IFFT section 1004.

[0080] IFFT section 1004 performs IFFT on the data converted in parallel, converts the frequency domain data into time domain data (data stream), and outputs the data to data selection section 1005.

The data selection unit 1005 also selects data for the time domain data force input from the IF FT unit 1004 in accordance with control from the data selection control unit 1009 described later.

CP adding section 1006 adds CP to the time domain data input from data selecting section 1005.

[0083] PZS conversion section 1007 converts the parallel data input from CP-attached cover section 1006 into serial data, and outputs the serial data to radio transmission section 1008.

[0084] Radio transmission section 1008 performs radio transmission processing on serial data, and performs antenna transmission.

Output to 1012.

The antenna 1012 transmits the data subjected to the wireless transmission process to the wireless reception device 400. Further, the antenna 1012 receives the feedback information from the wireless reception device 400 and outputs it to the wireless reception unit 1011.

Radio reception unit 1011 performs radio reception processing on the received signal and outputs the result to feedback information extraction unit 1010.

[0087] The feedback information extraction unit 1010 extracts feedback information indicating an error situation, a channel situation, and the like fed back from the radio reception device 400, and the data selection control unit 1

Output to 009.

Data selection control unit 1009 determines whether or not the transmission data is retransmission data based on the feedback information, and controls a data selection method in data selection unit 1005 according to the determination result.

In wireless reception device 400, antenna 1021 receives data transmitted from wireless transmission device 300 and outputs the data to wireless reception unit 1022. In addition, the feedback information from the wireless transmission unit 1033 is transmitted to the wireless transmission device 300. Radio reception section 1022 performs radio reception processing on received data, and outputs the result to SZP conversion section 1023.

[0091] SZP conversion section 1023 converts the serial data input from radio reception section 1022 into parallel data, and outputs the parallel data to CP removal section 1024.

[0092] CP removing section 1024 receives parallel received data input from SZP converting section 1023.

The CP is removed and output to the data synthesis unit 1025.

The data synthesis unit 1025 is configured to perform CP removal unit 1 according to the control from the data synthesis control unit 1031.

The time domain received data input from 024 is combined with the original data in the frequency domain to generate synthesized data, which is output to the FFT unit 1026.

The FFT unit 1026 performs an FFT on the combined data input from the data combining unit 1025 to convert it into frequency domain combined data, and outputs it to the PZS conversion unit 1027.

[0095] PZS conversion section 1027 converts the frequency domain composite data input from FFT section 1026 into serial and outputs the result to demodulation section 1028.

Demodulation section 1028 demodulates serial data and outputs it to decoding section 1029.

[0097] Decoding section 1029 decodes the demodulated data to generate restored data, and error detection section 10

Output to 30.

[0098] Error detecting section 1030 detects whether or not there is an error in the restored data input from decoding section 1029, and outputs the detection result to feedback information generating section 1032.

[0099] The feedback information generation unit 1032 generates feedback information based on the detection result from the error detection unit 1030 and the channel information (not shown) of V and the channel estimation unit. Then, feedback information generation section 1032 outputs the generated feedback information to data composition control section 1031 and radio transmission section 1033.

[0100] Based on the feedback information from feedback information generation section 1032, data composition control section 1031 determines whether or not the received data is retransmission data. If it is determined that the data is retransmission data, the data composition control unit 1031 outputs to the data composition unit 1025 an instruction for combining the received data with the original data. On the other hand, if it is determined that the data is not retransmission data, the data composition control unit 1031 does not synthesize the received data! /, And outputs an instruction to the data composition unit 1025. [0101] Radio transmission section 1033 performs a radio transmission process of feedback information, and outputs the result to antenna 1021.

FIG. 11 is a retransmission flow diagram according to the present embodiment. Radio transmitting apparatus 300 converts the transmission data into transmission data in the time domain by IFFT (S1110), determines whether this transmission data is a retransmission data card (S1111), and determines that it is retransmission data. In the case (Y ES in S1111), a part of transmission data in the time domain is selected as retransmission data (S1112). Then, CP is added to the selected retransmission data, PZS converted, and transmitted from the antenna 1012 (S1113). On the other hand, radio receiving apparatus 400 determines whether or not the received data is retransmission data (S 1114), and determines that the received data is retransmission data (YES in S 1114), the retransmission data is the original data. (S1115). Next, it is converted into composite data in the frequency domain by the composite data force FFT (S 1116). Whether or not there is an error in this combined data is detected (S1117), and if an error is detected (NO in S1117), it is determined whether or not the number of retransmissions exceeds the maximum number of retransmissions (S1118), and the maximum number of retransmissions is determined. If the number of times has not been exceeded! / (NO in S1118) Send a retransmission request.

[0103] If no error is detected in step S1117, the process ends. If an error is detected in step S 1117 but it is determined in step S 1118 that the number of retransmissions has exceeded the maximum number of retransmissions, the process ends.

FIG. 12 is a flowchart of subcarrier selection processing at the time of retransmission according to the present embodiment.

FIG. 12 is a diagram showing details of step S1112 in the flowchart of FIG. The data selection control unit 1009 determines a corresponding puncture matrix with reference to Table 1 based on the fed back channel condition and the number of retransmissions (S 1120), and outputs it to the data selection unit 1005. The data selection unit 1005 selects data according to the puncture matrix designated by the data selection control unit 1009 (S1121).

[0105] As described above, in order to select the data after IFFT, that is, the data power in the time domain different from the data in the frequency domain at the time of initial transmission, and the retransmission data, the frequency is included in the selected part of the retransmission data. Contains all data for the region. On the receiving side, the received time-domain retransmission data is combined with the original data and FFT is performed, so that the error rate characteristics of all data can be improved. [0106] Note that the selection method described in Embodiment 1 can be similarly applied to the OFDM system according to the present embodiment. In this case, the selection target is a sub data stream instead of a subcarrier. It becomes.

[0107] The disclosures of the description, drawings and abstract contained in the Chinese application with Chinese application number 200610009555.8 filed on February 24, 2006 are all incorporated herein by reference.

Industrial applicability

The present invention can be applied to a wireless communication system that performs retransmission.

Claims

The scope of the claims

[1] transmission data generating means for generating time domain or frequency domain transmission data;

A retransmission data generation means for generating retransmission data in an area different from the area of the transmission data;

A wireless communication apparatus comprising:

[2] The retransmission data generation means includes:

When the transmission data is time domain data, the transmission data is converted into frequency domain data to generate the retransmission data,

If the transmission data is frequency domain data, the previous transmission data is converted to time domain data to generate the retransmission data.

The wireless communication device according to claim 1.

[3] The retransmission data generation means generates the retransmission data by selecting data in order from the transmission data at regular intervals or at random.

The wireless communication device according to claim 1.

[4] Control means for performing control to reduce the data amount of the retransmission data as the number of retransmissions increases.

The wireless communication device according to claim 1.

[5] When the channel condition is good, the data amount of the retransmission data is less than half of the data amount of the transmission data,

Control means for performing control to make the data amount of the retransmission data more than half of the data amount of the transmission data when the channel status is bad,

The wireless communication device according to claim 1.

6. The radio communication apparatus according to claim 1, further comprising a control unit that sets a puncture matrix indicating the retransmission data generation method corresponding to a combination of the number of retransmissions and the channel status in the retransmission data generation unit.

[7] A transmission data generation step for generating time domain or frequency domain transmission data, and a retransmission data generation step for generating retransmission data in a different area from the transmission data area. And

A retransmission data generation method comprising: