The Decoding Performance Research For Nonbinary Low-Density Parity Check Codes

As we know, the low density parity check (LDPC) codes are the best codes in the field of channel coding applications. With approaching Shannon limit, they have been employed in various areas of telecommunications. Compared with Binary LDPC, Non-binary LDPC codes which based on high order finite fields GF(q) are more capable of rectifying burst and random noises, and can meet the high requirements of modern telecommunication. So it is evoked extensive research interests from the academic area.For the moment, there have been sophisticated researches about LDPC codes in GF (2) While for LDPC codes in GF (q),q^2, the very large decoding complexity limits their applications. Thus, how to cut down this complexity but guaranteeing the performance has become the choke point in the research of the LDPC codes in GF (q),q^2.This thesis investigates the decoding performance of the non-binary LDPC codes and the improved methods. The main contents are as follows.At first, based on the coding and decoding theory of LDPC codes, this thesis analyses the aims of studying non-binary LDPC codes and shows the reasons for the difference between non-binary and binary. Thus based on the coding and decoding algorithms of LDPC codes, this thesis investigates the existing traditional decoding algorithms, such as BP algorithm, and the fast decoding algorithm such as EMS algorithms, and compaer their performance.What’s more, we established the coding and decoding simulation platform, and simulated the EMS performance of non-binary LDPC codes. It analyzes the decoding performance of the sort numbers, and proposed the select sort numbers method, in a certain degree of complexity and performance, for the application and development with the EMS decoding algorithm.Finally, the thesis optimizes the EMS decoding performance with the correction factor, and comprehensive analysis the impact of the correction factor to the decoding. Afterwards this thesis summarized the impact for various values of correction factor. How to select and use the correction factor relying on the use requirements is also dicussed, which benefits the relevant study and application progress.