A method for constructing a code-rate-compatible protograph LDPC code based on deep space communication environment

Abstract

The invention discloses a method for constructing a code-rate-compatible protograph LDPC code based on deep space communication environment. The method includes: 1) obtaining multiple code-rate-compatible protographs based on row and column extension of an ARAPA proto matrix; 2) then executing extension four times on the obtained series of protographs in a PEG algorithm, to remove multiple edges and obtain the protograhs having no multiple edges; and 3) lastly executing extension several times on the above protographs in the PEG algorithm again, to obtain the code-rate-compatible protograph LDPC code having certain code length and having quasi-cyclic characteristic. This code-rate-compatible LDPC code constructed based on the matrix extension method has a lower decoding threshold and a lower error-code floor. Compared with code-rate-compatible LDPC code constructed based on AR4JA protographs, the code-rate-compatible LDPC code constructed based on the present method has the similar performance thereto, however has the lower decoding threshold and decoding calculation complexity, and has superior performance especially in the case of high code-rate, which can obtain the performance gain of about 0.2 dB in the case that BER is 10<-6>.

Description

technical field [0001] The invention relates to the technical field of channel coding for deep space communication systems, in particular to a method for constructing code rate compatible protograph LDPC codes. Background technique [0002] The deep space communication environment has the characteristics of long transmission distance, large delay, low signal-to-noise ratio, high bit error rate, asymmetric link rate, and limited transmission power. Therefore, constructing a high-performance, low-complexity channel coding suitable for the deep space communication environment has become a key technology to ensure the reliability and effectiveness of the deep space communication system. The Low-Density Parity-Check (LDPC) code has a parallel decoding structure, is more suitable for high-speed hardware implementation, and has a lower error floor. It is considered to be the code with the best error correction performance so far. In 2003, NASA's Aerodynamics Laboratory (JPL) propo...

AI Technical Summary

Problems solved by technology

[0005] In view of the prior art, at present, the rate-compatible LDPC code is constructed by the perforation technology for the original model graph, and there is a defect that the decoding performance of the high-rate subcode obtained after perforation is seriously degraded. Aiming at this defect, the proposed The design rate-compatible LDPC code based on the proto-matrix extension method often needs to be expanded based on the superior-performance proto-graph. However, the current traditional method is mainly based on the extension of the AR4JA proto-graph to construct a code-rate-compatible LDPC code. Due to the shortcomings of suboptimal performance and high decoding complexity, it is urgent to select a protograph with better performance, lower decoding threshold and decoding computational complexity than the AR4JA protograph to construct a rate-compatible protograph. Figure LDPC code to meet the needs of deep space communications, the purpose of the present invention is to provide a method that can overcome the serious decline in decoding performance of high codewords after puncturing, lower decoding threshold and decoding computational complexity The code rate compatible protograph LDPC code construction method based on the deep space communication environment, the technical solution of the present invention is as follows: a code rate compatible protograph LDPC code construction method based on the deep space communication environment, which comprises the following steps:

Images