JP2008227811A - Retransmission control system by ir method in hybrid automatic retransmission of radio communication - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain retransmission by an effective puncturing pattern adapted to a reception state concerning a retransmission control method by an IR method in the hybrid automatic retransmission of radio communication. <P>SOLUTION: A transmission-side apparatus includes a puncturing pattern control part for performing control to encode transmission data and to select a pattern which is indicated by a reception-side apparatus in retransmission among the plurality of puncturing patterns. The reception-side apparatus includes: a synthesizing part for synthesizing transmitted signals; a decoding part for decoding an output; a comparison part for comparing an output of the synthesizing part with the output of the decoding part; and a plurality of counters. The plurality of counters count non-coincidence signals from the comparison part in response to a signal which expresses a validity degree from a pattern validity degree generating part. The counter whose values is maximum among values of the plurality of counters is determined. The transmission-side indicates the number of the puncturing pattern corresponding to the determined counter as the pattern used in the succeeding retransmission. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a retransmission control method using an IR (Incremental Redundancy) method in hybrid automatic retransmission of wireless communication.

  In mobile communication technologies such as mobile phones, the 3rd Generation Partnership Project (3GPP) provides high speed downlink packet access (HSPDA) specifications for high speed data transfer, including HARQ. There is a retransmission technique based on (Hybrid Automatic Repeat Request). For HARQ retransmission, the same bit is retransmitted and the soft decision value (likelihood or probability value) received at the receiving side is combined with the retransmitted soft decision value to obtain SINR (Signal Interface Noise Ratio). There are a Chase synthesis method and an IR method for decoding with improved noise ratio. In the IR method, bits that have not been transmitted at the time of retransmission are transmitted and combined to reduce the equivalent coding rate (increase redundancy) and improve error correction capability for decoding.

  FIG. 6 is a conceptual explanatory diagram of the Chase method and the IR method. A radio signal is first transmitted from the transmission side (a in FIG. 6). In the Chase method, data of the signal is stored (indicated by C1), an error check is performed, and if there is an error, a NACK is notified to the transmitting side (b in FIG. 6), and the same signal is retransmitted on the transmitting side (FIG. 6). C), the receiving side combines the signal C1 received first and the signal C2 received the retransmission signal. After this, if there is an error, retransmission is repeated further.

  In the IR method, first, a transmission signal is processed with data (D) by puncturing pattern 1 and transmitted. The puncturing pattern represents a bit pattern in which the bit position of the data to be transmitted is “1” and the bit position of the data to be prohibited (deleted) is “0”, and the bit string D1 in FIG. In this example, the transmission data (encoded data) is modified by “101100”). If an error is detected as a result of receiving this data at the receiving side and checking it, if NACK is notified to the transmitting side, data (D) is now sent to the transmitting side by puncturing pattern 2 (in the example of FIG. 010011 "). In the example shown in the figure, the puncturing pattern 2 is a pattern obtained by inverting “1” and “0” of the puncturing pattern 1. On the receiving side, the data D1 received first and the retransmitted data D2 are combined.

  FIG. 7 shows the configuration of the transmission side and the reception side by the IR method. As shown in FIG. 7, when data is set in the retransmission buffer 60 on the transmission side, the processing of the encoding unit 61 for error correction or the like is performed, and the encoded data is subjected to a pre-selected puncturing pattern. The processing of the puncturing unit 62 is performed and transmitted. On the receiving side, when data is first received, the combining unit 63 stores the data in the retransmission buffer 64 and decodes the received data to data before being encoded by the decoding unit 65. In the case of retransmission, the data stored in the retransmission buffer 60 on the transmission side is encoded by the encoding unit 61, punctured by the puncturing unit 62 and transmitted, and transmitted by the combining unit 63 on the reception side. The first received data stored in the data and the retransmitted data are combined, and the combined data is decoded by the decoding unit 65.

  When performing retransmission control using such a puncturing pattern, a plurality of puncturing patterns may be used. However, it is desired to improve efficiency by reducing the number of retransmissions. The structure is shown in FIG. 8 (see Patent Document 1). 8, 70 is a radio base station, 71 is a scheduler, 72 is a redundant version control unit (the redundant version is the same as the puncturing pattern), 73 is a HARQ processing unit, 74 is an ACK / NACK receiving unit, and 75 is a CQI (Channel Quality). Indicator: Represents the state of the downlink propagation path).

The redundant version control unit 72 of the scheduler 71 of the radio base station 70 in FIG. 8 causes the HARQ processing unit 73 to execute retransmission control when NACK is returned as a response from the counterpart station by the ACK / NACK receiving unit 74. In this case, a retransmission version selection process is performed. In that case, it is determined whether the version (pattern) prioritizing systematic bits last time. If it is prioritized, Nsys-Ndata (Nsys is the number of input bits of the physical layer, Ndata is the output from the HARQ processing unit 74) The number of bits) is positive and the number of codes is limited. If the systematic bits are not prioritized, the systematic bits are prioritized after determining whether the number of retransmissions exceeds the threshold. Or a version that prioritizes systematic bits, and if the number of retransmissions exceeds a threshold, a version that prioritizes systematic bits is selected.
JP 2006-94318 A

  In retransmission control using the conventional IR method, puncturing patterns are selected regularly (for example, two patterns are selected alternately) as shown in FIG. In that case, after all the puncturing patterns have been used, only regular selection is repeated. Therefore, there is a possibility of performing unnecessary retransmission using a puncturing pattern effective for bits that have already been received normally. is there.

  Further, according to the technique of Patent Document 1 shown in FIG. 8 above, the version (pattern) is selected by the judgment on the transmission side, and the version that always gives priority to the systematic bit when the number of retransmissions is equal to or greater than the threshold value. This is a selection and does not select a puncturing pattern adapted to the reception status on the receiving side, and does not prevent useless retransmission.

  An object of the present invention is to provide a retransmission control method using an IR method in hybrid automatic retransmission of wireless communication that can realize retransmission by an effective puncturing pattern adapted to a received situation without cost.

  FIG. 1 is a diagram showing a principle configuration of the present invention. In the figure, 1 is a transmission side device, 1a is a reproduction buffer unit, 1b is an encoding unit that performs encoding for an error correction function, 1c is a puncturing pattern holding unit that holds n puncturing patterns, and 1d is A puncturing pattern control unit, 1e is a puncturing unit that punctures encoded data according to a selected puncturing pattern, 1f is a transmitting unit, and 1g is a receiving unit that detects a response from the receiving side. 2 is a receiving side device, 2a is a receiving unit, 2b is a combining unit, 2c is a buffer, 2d is a decoding unit that performs decoding including error correction, 2e is a comparison unit, and 2f is the effectiveness of each puncturing pattern ( Puncturing pattern effectiveness generation unit for generating “1”), 2g-1 to n are counters that count the number of mismatched bits from the comparison unit 2e when they are valid bits of the puncturing pattern, 2h is a determination unit, 2i is a check unit.

  In the transmission side device 1, when retransmission data (at the time of retransmission) or input data (at the time of initial transmission) from the reproduction buffer unit 1a is encoded by the encoding unit 1b and input to the puncturing unit 1e, a puncturing pattern control unit Under the control of 1d, the puncturing unit 1e performs puncturing on the encoded data according to the pattern selected from the puncturing pattern holding unit 1c, and the output is transmitted as a radio signal via the transmitting unit 1f. In the receiving side device 2, the data is demodulated by the receiving unit 2a, and the data received up to the previous time is combined with the data stored in the buffer 2c by the combining unit 2b, and the combined data is input to one input side of the comparison unit 2e. At the same time, the decoded data is supplied to the decoding unit 2d, decoded, corrected by decoding, and decoded data is input to the other input side of the comparison unit 2e, and the two data are compared. The comparison unit 2e compares the data before and after decoding (after correction) for each bit, and inputs an output indicating coincidence or mismatch to the plurality of counters 2g. Each counter 2g-1 to n is provided for each pattern (n) from the puncturing pattern validity generation unit 2f, and a comparison corresponding to a valid bit (referred to as "1") of the corresponding puncturing pattern. The mismatched bit output from the unit 2e is counted.

  That is, when the puncturing pattern is “1” indicating validity, an output indicating mismatch (“1”, matching output is “0”) is generated from the comparison unit 2e, and the corresponding counter is counted up. When reception of one data block is completed, the determination unit 2h determines the counter having the largest count value from the count values of the counters 2g-1 to 2n, and determines the determined counter (of 2g-1 to n). 1) is sent from the transmission unit 2j to the transmission side apparatus 1 as the number of the puncturing pattern to be used in the next retransmission. In other words, puncturing patterns with a large number of corrections (mismatches) can be estimated to be low in reliability, so it is highly possible that the number of retransmissions will be reduced by specifying a puncturing pattern with a larger number of corrections and making a retransmission request. Become. In the transmission side device 1, when an instruction of the pattern number to be used for retransmission is supplied from the reception unit 1g to the puncturing pattern control unit 1d, the number of the number instructed from the puncturing pattern holding unit 1c to the puncturing unit 1e. Control to perform puncturing using a pattern.

  In the receiving side device 2, the data decoded by the decoding unit 2d is checked by the check unit 2i, an error is detected, and a retransmission is made by sending a response of NACK (response to error detection) to the transmission side. Required and the pattern number is valid.

  In the above description, the counting operations of the counters 2g-1 to 2g-n count +1 if the bit patterns from the corresponding puncturing pattern validity generation unit 2f do not match when the bit patterns are "1". However, by assigning a weight to the bit position of the puncturing pattern and setting “+2” and “+5” for the important bit positions, if a mismatch is detected at that position, the corresponding counter is set. “+2” and “+5” can be counted up.

  FIG. 2 shows an operation example based on the principle of the present invention, in which two patterns are used as puncturing patterns. In FIG. 2, “a” is “101100” for pattern 1 and “010011” is for pattern 2 in b. c1 and c2 are received data first transmitted from the transmission side, c1 represents data before correction (before decoding), and c2 represents data after correction (after decoding). When c1 and c2 are compared by the comparison unit 2e shown in FIG. 1, the rear two bits of the bit string are inconsistent, but the bit of the pattern 1 corresponding to the position of the second two bits is “00”. The count value of the counter corresponding to pattern 1 (2g-1 in FIG. 1) is “0”, but the bit of pattern 2 is “11”, so the two bits are counted. The count value of the counter (2g-2 in FIG. 1) corresponding to the pattern 2 is “2”. In this case, the receiving side instructs the transmitting side to select “Pattern 2” and perform puncturing. Data before and after correction of data retransmitted by this instruction is d1 and d2. With respect to this data, the counter for pattern 1 for comparison using pattern 1 is “0”, and the counter for pattern 2 is “1”. Therefore, the receiving side again instructs the transmitting side to select “Pattern 2” and perform puncturing. In response to this, when data punctured by “pattern 2” is sent from the transmission side, pre-correction data and post-correction data indicated by e1 and e2 in FIG. 2 are obtained. In this case, no mismatch is detected for either pattern 1 or pattern 2.

  According to the present invention, by specifying and retransmitting a puncturing pattern that is estimated to be most effective based on the number of corrections, the number of retransmissions can be reduced, radio resources can be used efficiently, and effective throughput can be improved. be able to.

  FIG. 3 is a diagram showing the configuration of the embodiment. In the figure, 1 is a transmission side device, 10 is a retransmission buffer unit, 11 is a data selection unit, 12 is an encoding unit, 13 is a puncturing pattern table, 14 is a puncturing unit, 15 is a puncturing pattern control unit, and 16 is A modulation unit 17 is a demodulation unit. 2 is a receiving side device, 20 is a demodulation unit, 21 is a synthesis unit, 22 is a buffer unit, 23 is a decoding unit, 24 is a CRC check unit, 25 is a comparison unit, and 26 is a puncturing pattern validity table (2f in FIG. 27-1 to 27-4 are counting units 1 to 4, and 28 are puncturing pattern selection units. In this embodiment, it is assumed that there are four puncturing patterns.

  FIG. 4 is an example of a flowchart of puncturing pattern selection of the transmission side apparatus. First, it is determined whether or not the transmission is new (S1 in FIG. 4). If the transmission is new, the process ends using puncturing pattern 1 (S2). If it is not a new transmission, it is determined whether it is a retransmission and the first time (S3), and if it is the first time, a puncturing pattern 2 is used (S4). If it is not the first retransmission but the second or more times, the puncturing pattern instructed by the receiving side is used (S5 in FIG. 4).

  The overall operation in the configuration of FIG. 3 will be described. When data is first transmitted in the transmission side apparatus 1, the input data is input to the data selection unit 11 and is also set in the retransmission buffer unit 10, and the data selection unit 11 Then, the input data is selected, and the input data is encoded (redundant) by the encoding unit 12 by a method capable of error correction by the conventional technique and input to the puncturing unit 14. In the puncturing unit 14, the puncturing pattern 1 is selected in the case of new transmission according to the flow of FIG. 4 under the control of the puncturing pattern control unit 15 with respect to the input data, and the puncturing pattern 2 is selected in the first retransmission. The puncturing pattern control unit 15 selects a pattern designated by the receiving-side apparatus 2 at the second or more retransmissions.

  The puncturing unit 14 performs puncturing using the selected puncturing pattern, and the output data is modulated by the modulation unit 16 and transmitted from the antenna, and is input to the demodulation unit 20 from the antenna of the receiving side apparatus 2. The demodulated data is combined with the contents of the buffer unit 22 (not initially included) in the combining unit 21, and the combined result is supplied to the decoding unit 23 and the comparison unit 25. The data decoded by the decoding unit 23 (including error correction) is supplied to the comparison unit 25. The comparison unit 25 compares the data, and the bit pattern representing the match / mismatch as the comparison result is displayed in the count unit 1 to the count unit 4. When the signals representing the four pattern validity (positions of “1”) from the puncturing pattern validity table 26 coincide with each other, they are counted up (+1) each time they coincide. When reception of a series of bit strings is completed, the count values of the counting units 1 to 4 are supplied to the puncturing pattern selection unit 28 to identify the counting unit having the largest count value and its number (the number of the puncturing pattern). Output). On the other hand, the CRC check unit 24 checks the data decoded by the decoding unit 23. If an error is detected, a NACK (retransmission request) response is generated and modulated together with the pattern number generated from the puncturing pattern selection unit 28. The data is transmitted from the receiving apparatus 2 to the transmitting apparatus 1 through the unit 29. The receiving-side apparatus 2 counts the number of retransmission requests (holds a count value by a register or the like not shown), and controls so that the count unit 27 does not count the number of mismatches at the first retransmission request. Alternatively, the number of mismatches may be counted by the counting unit 27 for all retransmission signals, and the number of the counting unit 27 having the maximum count value may be transmitted to the transmission-side apparatus 1. In this embodiment, the transmission side apparatus 1 selects the puncturing pattern 2 in the case of the first retransmission (see FIG. 4), but can be changed so as to select from the first retransmission.

  When receiving the response, the transmitting side device 1 demodulates the signal by the demodulating unit 17, supplies the NACK signal to the data selecting unit 11, selects the data stored in the retransmission buffer unit 10, and selects the first data by the encoding unit 12. Encoding similar to transmission is performed, and the encoded data is supplied to the puncturing unit 14. On the other hand, when the puncturing pattern number designated by the receiving side apparatus 2 is supplied to the puncturing pattern control unit 15, the puncturing unit 14 is controlled to select the designated pattern from the puncturing pattern table 13. Operate to puncture.

  FIG. 5 shows an example of a puncturing pattern. FIG. 5 shows a case where four patterns are used as puncturing patterns, and each pattern is composed of systematic (systematic) bits, redundant bits 1 and redundant bits 2. Puncturing pattern 1 gives priority to systematic bits and all bits are “1”, puncturing pattern 2 gives priority to redundant bits, and systematic bits are all bits “0”. Puncturing pattern 3 has priority in the first half of the code block and is “1” only in the first half of the systematic bit, and puncturing pattern 4 has priority in the second half of the code block and is “1” only in the second half of the systematic bit.

  When counting is performed in the counters 27-1 to 27-4 of the receiving-side apparatus 2, the pattern validity score from the puncturing pattern validity table 26 can be added. For example, if systematic bits are included in the puncturing pattern, +5 points can be weighted, and the number included in the redundant bits related to the corresponding bits can be increased by +1.

  Further, when four patterns are used as shown in FIG. 5 as the puncturing patterns, the first puncturing pattern 1 is transmitted with the systematic bit priority, and the first retransmission is performed with priority on the untransmitted redundant bits. When 2 is transmitted, since all bits have been transmitted after the second retransmission, transmission is performed according to the puncturing pattern instruction from the receiving side. In this case, the counting unit 1 and the counting unit 2 on the receiving side can be deleted, and only one of the patterns 3 and 4 can be specified as the puncturing pattern instruction.

It is a figure which shows the principle structure of this invention. It is a figure which shows the operation example by the principle of this invention. It is a figure which shows the structure of an Example. It is a figure which shows the example of the flowchart of the puncturing pattern selection of a transmission side apparatus. It is a figure which shows the example of a puncturing pattern. It is a conceptual explanatory view of the Chase method and the IR method. It is a figure which shows the structure of the transmission side and receiving side by IR method. It is a figure which shows the structure of the proposed technique.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transmission side apparatus 1a Reproduction | regeneration buffer part 1b Encoding part 1c Puncturing pattern holding part 1d Puncturing pattern control part 1e Puncturing part 1f Transmission part 1g Reception part 2 Reception side apparatus 2a Reception part 2b Synthesis | combination part 2c Buffer 2d Decoding part 2e Comparison unit 2f Puncturing pattern validity generation unit 2g-1 to n counter 2h determination unit 2i check unit 2j transmission unit

Claims (4)

Retransmission control method by IR method in hybrid automatic retransmission of wireless communication,
The transmission side device includes a puncturing pattern control unit that encodes transmission data and selects a pattern instructed by the reception side device from among a plurality of puncturing patterns, and performs puncturing control during retransmission. ,
The receiving side device combines a signal transmitted from the transmitting side device with a previously received signal, a decoding unit that decodes a signal from the combining unit, an output signal of the combining unit, and an output of the decoding unit A comparison unit for comparing signals, a plurality of counters corresponding to the puncturing patterns, and a pattern effectiveness generation unit for generating the effectiveness of each puncturing pattern,
Each of the plurality of counters counts a signal indicating a mismatch from the comparison unit when there is a signal indicating the effectiveness of a puncturing pattern corresponding to each from the pattern effectiveness generation unit, A determination unit configured to determine a counter having a maximum count value among the plurality of counters, and the puncturing pattern number corresponding to the determined counter is used for the next retransmission to the transmitting side device; A retransmission control method based on an IR method in hybrid automatic retransmission of wireless communication, characterized by indicating as a pattern. In claim 1,
The receiving device includes a check unit that performs error checking by inputting an output signal from the decoding unit,
When an error is detected in the check unit, a retransmission request is transmitted to the transmitting side device together with an instruction of the puncturing pattern, and a retransmission control method using an IR method in hybrid automatic retransmission of wireless communication. In claim 1,
The puncturing pattern validity generation unit of the reception side device generates weighted points different depending on bit positions, and adds the weighted numerical value to the counter, and performs IR in hybrid automatic retransmission of wireless communication Retransmission control method by law. In claim 1,
At the time of new data transmission, the transmitting side apparatus transmits using a pattern in which systematic bits are prioritized as a puncturing pattern, and firstly retransmits redundant bits that have not been transmitted first. A retransmission control method using an IR method in hybrid automatic retransmission of wireless communication, wherein retransmission is performed according to a puncturing pattern instruction from a receiving side.

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