Research On The Decoding Algorithms Of Ldpc And Performance Analysis

Channel coding is an important part of digital communication system.It is one of the key technologies to ensure the information being transported correctly.LDPC code is an efficient channel coding method that is comparable with Turbo code with low decoding complexity and good performance.It has been payed more and more attention and been widely used.This paper is to the theoretical analysis.It is maded up with comprehensive analysis and research on the performance and realization of encoding and decoding algorithms as well as the design optimization of parity-check matrix based on the methods of DE and EXIT.At first,this paper introduces many encoding and decoding algorithms with derivation and simulation results of specific LDPC codes. Using DE and EXIT to analyze the gradual convergence of LLR-BP with specific channel conditions. Further discussion of the first time of decoding judgment based on the simulation results of stopping criterions is made.Analyze the perfomance of LDPC-BICM and LDPC-BICM-ID systems and the differences of different constellations based on 8PSK modulation.At the end of this paper,we design a set of LDPC codes whose code length are as long as the codes in 802.16e using PEG method and spacial degree distribution sequence.We compare the perfomance of the LDPC codes designed with the codes in 802.16e.