Research On The Structure And Application Of SC-LDPC Codes

In channel coding,the spatially coupled low density parity check(SC-LDPC)code can approach the shannon limit theoretically due to its "threshold saturation" characteristic.Compared with LDPC codes,the spatial coupling structure of SC-LDPC codes can bring higher performance gains and is more suitable for streaming data transmission systems.However,as the requirements for the reliability of the communication system continue to increase,how to construct an SC-LDPC code that meets the performance requirements has become the focus.In order to achieve the purpose of further improving the reliability of the system,this paper mainly studies the method of constructing SC-LDPC codes based on LDPC code check matrix.Based on the previous research,a construction scheme of rate compatible SC-LDPC codes is proposed.To further verify the feasibility of the application of SC-LDPC code,rate-compatible SC-LDPC codes to hybrid automatic repeat request(HARQ)retransmission technology is applied to designed a HARQ retransmission technical solution with rate compatible SC-LDPC codes.The main research contents of this paper are as follows:First,this paper gives the definition and representation method of SC-LDPC code,and theoretically derives the principle of coding algorithm and decoding algorithm,and lays the foundation for the research of check matrix construction algorithm.Secondly,in the process of constructing SC-LDPC codes,this paper proposes a single-edge coupling algorithm that couples the base matrix of LDPC codes constructed by progressive edge growth(PEG)algorithm.In the coupling algorithm,the performance of the SC-LDPC code is improved by restricting the edges selected for coupling.The simulation shows the performance of the SC-LDPC code constructed by the proposed coupling algorithm outperform that of the 5G NR LDPC code with the same parameters over additive white gaussian noise(AWGN)channel.Then,in order to adapt to the time-varying channel,only one encoder/decoder pair is required to accomplish the encoding and decoding of SC-LDPC codes of different code rates.This paper designs a rate-compatible SC-LDPC code based on the Raptor-Like structure.A rate-compatible coupling algorithm is proposed for the base matrix of the Raptor-Like structure.The design method in this paper has a simple structure,which is easier to implement and can offer eight code rates.Moreover,the sliding window reciprocal channel approximation(RCA)algorithm is designed on the basis of RCA algorithm.The threshold of the rate compatible SC-LDPC code is calculated through the sliding window RCA algorithm.This paper verifies and analyzes the performance of SC-LDPC code simulation over AWGN channel.Finally,this paper applies the rate-compatible SC-LDPC codes to HARQ retransmission strategy as well as develops a cyclic redundancy scheme and HARQ retransmission strategy for rate-compatible SC-LDPC codes to ensure high-reliability transmission.simulation results show that under the same decoding complexity,the HARQ retransmission technical solution designed in this paper outperform that of the 5G NR LDPC code retransmission under the same parameters with transmission times of 1,2,and 3.