CN101621367B

CN101621367B - HARQ decoding method based on packet check information

Info

Publication number: CN101621367B
Application number: CN2009100624536A
Authority: CN
Inventors: 王德胜; 付代宇; 俞锦; 林宏志; 刘应状; 葛晓虎; 朱光喜; 屈代明; 郝亮
Original assignee: Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology
Priority date: 2009-06-09
Filing date: 2009-06-09
Publication date: 2012-11-14
Anticipated expiration: 2029-06-09
Also published as: CN101621367A

Abstract

The invention provides an HARQ decoding method based on packet check information, which comprises the following steps: (1) after a received frame is decoded on a physical layer, submitting the received frame to a data link layer, utilizing the tail CRC (cyclic redundancy check) of a PDU (Protocol Data Unit) to check the accuracy of a package, feeding back an index value of an erroneous package and buffering the frame; (2) retransmitting the erroneous PUD packet and forming a frame with new data; if the decoding of the retransmitted erroneous package is still erroneous, carrying out combined decoding on the original erroneous frame with the new frame by a receiving end. The method feeds the information of the link layer back to the physical layer, specifically retransmits data by utilizing ARQ check indicator information, overcomes the defect of blind retransmission of the HARQ and sufficiently utilizes redundant information which is correctly decoded and contained in the PDU to carry out the combined decoding so as to effectively reduce the number of times of the retransmission and improve the throughput and the performance of a system.

Description

A kind of HARQ interpretation method based on packet check information

Technical field

The present invention relates to wireless communication technology, be specifically related to the automatic repeat requests of a kind of mixing (HARQ) interpretation method.

Background technology

Existing automatic repeat requests (ARQ) agreement like multiple rejections ARQ agreement, only simple carried out protocol Data Unit (Protocol Data Unit, re-transmission PDU) is not utilized the physical layer redundant information of makeing mistakes, and protocol efficiency receives certain restriction.In order in time-variant wireless channel, to reduce number of retransmissions as far as possible, farthest improve effective information throughput, generally all adopt the HARQ technology to improve transmission performance now.

HARQ combines the error control method of ARQ and FEC (forward error correction), makes full use of the useful information that retransmits in the code word, effectively reduces number of retransmissions, and system obtains the performance more excellent than traditional ARQ.

The HARQ technology is divided into three kinds usually: HARQ-I type, receiving terminal carry out FEC decoding and CRC (CRC) verification.Divide into groups wrong then request retransmission if receive, and abandon erroneous packet, transmitting terminal retransmits same packets; The HARQ-II type is referred to as incremental redundancy ARQ, and the incremental redundancy strategy is in first time during decoding failure, transmits additional redundancy information in addition again rather than whole data code groups is retransmitted once; The HARQ-III type is the improvement of complete incremental redundancy retransmission mechanism; In this mechanism; Each re-transmission can be carried out self-demarking code; Packet for each transmission adopts complementary deletion mode, and each packet both can be deciphered separately, also can synthesize an encoded packets with bigger redundant information and merge decoding.

Find that through investigation existing various technology all are to obtain extra redundant information through retransmitting, and do not make full use of the prior information that receiving terminal comprises, the increase of number of retransmissions makes overhead big, has reduced the throughput of system.

Summary of the invention

The present invention provides a kind of HARQ interpretation method based on packet check information, utilizes the redundant information that contains in the correct PDU bag of link layer to decipher error correction, effectively reduces number of retransmissions, improves the throughput of system.

A kind of HARQ interpretation method based on packet check information, the frame data of transmission comprise more than one protocol Data Unit (PDU) bag, and as shown in Figure 1, concrete steps are:

(1) transmitting terminal sends receiving terminal to after to the initial frame digital coding;

(2) receiving terminal to the numer of initial frames that receives according to deciphering; Decode results is wrapped fractionation; Each PDU bag that fractionation is obtained carries out cyclic redundancy code (CRC) verification, and the PDU bag that verification is correct is submitted to link layer, and the PDU bag index information of check errors is fed back to transmitting terminal;

(3) the PDU bag that transmitting terminal is corresponding with index information is encapsulated in the new frame data again, and the coding back retransmits gives receiving terminal;

(4) receiving terminal is deciphered successively, is wrapped the new frame data that receive and splits and CRC check, and the PDU that identification wherein retransmits wraps whether verification is correct, and the re-transmission PDU bag that verification is correct is submitted to link layer; For the re-transmission PDU bag of check errors, utilize the correct PDU bag of step (2) and (4) verification it to be done the decoding error correction as redundant information.

Technique effect of the present invention is embodied in:

The present invention is not limited to the existing thought of HARQ; Though similar HARQ-II retransmits local message, redundant information does not obtain through retransmitting, but link layer information is fed back in the physical layer; Utilize and deciphered correct package informatin, have the function that HARQ-III independently deciphers simultaneously; The present invention just makes error-correcting decoding to the specific PDU that makes mistakes once more after retransmitting, and therefore under the condition that guarantees error correcting capability, reduces retransmitting load, has reduced average delay effectively, and has been applicable to various chnnel codings.

Description of drawings

Fig. 1 representes system framework figure;

Fig. 2 representes embodiment of the invention schematic flow sheet;

Fig. 3 representes the core process figure of joint decoding error correction;

Fig. 4 is illustrated in the comparison sketch map of Packet Error Ratio under the different signal to noise ratio (snr)s;

Fig. 5 is illustrated in the comparison sketch map of the error rate under the different signal to noise ratio (snr)s.

Embodiment

Fig. 2 has provided the detail flowchart of an embodiment, and these embodiment concrete steps are:

A1. suppose that each PDU is surrounded by M bit data, L bit CRC check information, have in the frame n PDU bag (PDU_1, PDU_2 ..., PDU_n) coding adopts (3,1,2) convolution code, CRC generator polynomial g (x)=x ⁴+ x+1.Here get M=10, L=4, N=20.

A2. frame data are encoded through convolution code in the transmitting terminal physical layer, and the generator matrix of convolution code is G=[100; 101; 111].

A3. (channel is an additive Gaussian channel for Binary Phase Shift Keying, BPSK) modulation, and average is 0, and variance is 1, and the data after the modulation are sent out the frame of encoding to be carried out biphase phase shift keying.

A4. receiving terminal receives data and demodulation, and the data after the preservation demodulation are designated as initial frame, then initial frame is carried out the decoding first time.

A5. receive the end link layer to the first time decode results wrap fractionation, reduction obtains each PDU bag again, and corresponding steps A 1 be each PDU packet number (PDU_1, PDU_2 ..., PDU_n).

A6. receiving terminal carries out CRC check to each PDU bag.

A7. receiving terminal is through the correct and wrong PDU bag of CRC check information Recognition, and correct bag is committed to link layer, its numbering of erroneous packets record, and i and k PDU bag mistake in the instance, then with number information i, k feeds back to transmitting terminal, prepares to retransmit.

A8. transmitting terminal is with the numbering i of steps A 7 feedbacks, and the PDU bag that k is corresponding inserts in the new frame data, and this then is encapsulated into these two PDU bags again in the new frame and sends once more; The numbering of each PDU bag is followed successively by PDU_a1 in this frame, PDU_a2 ...; PDU_ai ... .PDU_ak ... ..; PDU_an, the PDU_ai that is numbered corresponding these the new frame data of PDU bag of i wraps, and is numbered the PDU_ak bag of corresponding these the new frame data of PDU bag of k.

A9. repeating step A2-A6, whether the PDU that retransmits through CRC check identification is correct, as correctly then being committed to link layer, then carries out the joint decoding error correction like mistake still, gets into steps A 10.

A10. receiving terminal carries out the joint decoding error correction to PDU still wrong after retransmitting, and the joint decoding error correction is a PDU information of utilizing decoding correct, reduces the uncertainty of decoding, carries out error correction, its core process such as Fig. 3, and joint decoding can adopt following strategy:

1. PDU packet number PDU_ai that obtains correcting after retransmitting among the obtaining step A9 and still wrong PDU packet number PDU_ak;

2. with the PDU bag that is numbered PDU_i in the PDU that corrects (being numbered the PDU bag of PDU_ai) the replacement step A4 initial frame;

3. PDU still wrong after in the A4 initial frame, finding re-transmission wraps; This bag be numbered PDU_k, it is carried out error correction, suppose that in order to express easily the adjacent PDU bag of wrong PDU bag all is correct; Utilize the correct bag data in front and back to decipher error correction to wrong PDU bag; Adopt maximum-likelihood decoding in this instance, be specially: total (M+L) bit of the data bit of known error PDU bag and check digit just has 2 when then this PDU bag being carried out the iteration replacement ^M+LKind of combination, promptly 0 to 2 ^(M+L)-1Every kind of combination is carried out the convolution coding of steps A 2; Then with steps A 4 in the numer of initial frames preserved after the demodulation according to carrying out XOR, promptly obtain the Hamming distance of each combination and numer of initial frames certificate, the combination of selecting to have smallest hamming distance is as expection decoding error correction result.If all wrong situation of adjacent PDU bag occurs, can regard the PDU integral body of these several mistakes as a bag, do the decoding error correction according to aforesaid way again.

4. substitute the data in the wrong PDU bag with the expection decode results;

5. for other wrong bags, repeating step 3 and 4 gets final product.

Fig. 4 and Fig. 5 are the simulation result sketch mapes to above-mentioned instance, only once retransmit during emulation, and Fig. 4 is illustrated in the comparison of Packet Error Ratio under the different signal to noise ratio (snr)s, i.e. the comparison of the Packet Error Ratio behind the joint decoding among Packet Error Ratio after the decoding for the first time and the A10 among the A4.Fig. 5 is illustrated in the comparison of the error rate under the different signal to noise ratio (snr)s, i.e. the comparison of the error rate behind the joint decoding among the error rate after the decoding for the first time and the A10 among the A4.Can find out the present invention's performance of elevator system significantly by 2 figure.

Claims

1. HARQ interpretation method based on packet check information, the frame data of transmission comprise more than one protocol Data Unit (PDU) bag, and concrete steps are:

(4) receiving terminal is deciphered successively, is wrapped the new frame data that receive and splits and CRC check, and the PDU that identification wherein retransmits wraps whether verification is correct, and the re-transmission PDU bag that verification is correct is submitted to link layer; For the re-transmission PDU bag of check errors, utilize the correct PDU package informatin of step (2) and (4) verification it to be done the decoding error correction as redundant information.

2. a kind of HARQ interpretation method according to claim 1 based on packet check information; It is characterized in that; Said step (4) adopts the re-transmission PDU bag of maximum-likelihood decoding check errors; Promptly unite present frame and primary data frame, and utilize step (2) and the correct PDU package informatin of (4) verification to do the decoding error correction as redundant information.