Research On The Turbo, LDPC Encoding/Decoding And Implementation Of LDPC Decoding

LDPC codes and Turbo codes are the focus of research on decoding and encoding because they have good performance which approach to the Shannon Limit. Turbo codes are better than the other codes in low SNR. LDPC codes are relatively easy defined and can outperform the Turbo codes with sufficiently long block lenghs. Its decoding complexity is also lower than Turbo codes. Recently, LDPC codes have drawn the worldwide attentions in channel coding community due to its high performance and strong potential applications in practice.This thesis introduces the basic theory of Turbo codes, researchs the method of Turbo codes encoding and decoding, and analyses the factors which impact the performance of Turbo codes. The analyses are proved by the simulation results. Then this thesis offers a comprehensive study on the performance of LDPC codes. The author presents a new method for construction of irregular LDPC codes based on generator matrix in order to significantly reduce encoding complexity. The simulation results are obtained over AWGN and Rayleigh channel, and the results are also compared with those acquired by trandional approaches.Finally, this thesis analyses the implementation of LDPC decoding. This thesis implements LDPC decoding based on Nios II system. The hardware decoding algorithm is Log-BP algorithm. The hardware platform is EP1S4080B956C6, which is one series of Stratix, based on Nios development board, Stratix Pro(EP1S40). Based on it, the author finishes the design of Nios II system, program on the system and debugging of the program.