Application Of LDPC For Digital TV Terrestrial Broadcasting System

Error-correcting codes are widely used in many fields, such as mobile communication, satellite communication, and so on.'Low-Density Parity codes (LDPC)', one kind of Error-correction codes, is defined in terms of very sparse matrices, and can be decoded by iteration algorithms. It were first investigated in 1962 by Gallager, but appear to have been largely forgotten. Mackey and Wiberg rediscovered their excellent property of achieving information rates up to the Shannon limit, after the extreme success of Turbo codes.This dissertation presents a systematic investigation of LDPC codes. We introduce the theory foundation of LDPC, firstly, including Tanner graph, several constructions and responded encoding methods. Than we study the major decoding algorithms, BF, WBF, LP-WBF, BP and two other improved BP algorithms. Some simulation results for additive white Gaussian noise ( AWGN ) channel are given.As one of contributions of this dissertation, an improved decoding algorithm based on the BF algorithm (Iterate F-BF) is proposed. Compared with BF algorithm, it achieves considerable improvement for low column weight LDPC with almost the same complexity.The applications of LDPC codes are studied. We apply the LDPC to the Time Domain Synchronous OFDM(TDS-OFDM) system in Rayleigh fading channels. The OFDM parameters are selected according to Chinese Digital TV Terrestrial broadcasting standards.