A Study Of LDPC Codes For NGB-W System

Error control coding is an important technique to ensure the reliable of transmission information in wireless communication systems. Low Density Parity Check code, whose performance is close to the Shannon limit, has attracted great attention since its “rediscovery” and LDPC codes with low decoding complexity, the flexible structure, and the excellent performance has become one of the great research progresses since the information theory proposed. So far LDPC codes have been applied to the field of the deep space Telecommunication, satellite communication, digital video and audio broadcasting.Broadcast television network is the most widely used dissemination carrier for the public information, and deliverys the information to the vast number of the family users conveniently, with the development of the information technology, and the increasing demand on the wireless service, the traditional broadcast networks and traditional bidirectional communication network has been unable to realize the optimization of mobile information transmission service. Therefor the next generation broadcast network wireless systems(Next Generation Broadcast Network Wireless Systems, NGB-W) emerge as the times require. In this paper, combined with the practice in wireless technology research center of new media in Shanghai advanced research institute of the Chinese Science Academy to participate in the “next generation broadcasting network wireless systems(NGB-W)” project, my main job is to study on the module of bit interleaved coded modulation(Bit Interleaved Coded Modulation, BICM) in the NGB-W system, and research LDPC codes which is adopted by the channel coding of this system.This paper first introduces the development history and research status of LDPC codes, then this paper briefly introduces the basic principle of LDPC code and the factors which influence the performance of LDPC codes and some basic decoding algorithms of LDPC codes. Then, elaborates the construction methods of LDPC codes, including the structured construction and the random construction, the structured construction although constructed codes have certain structure rules to reduce the encoding complexity, but it lacks the flexibility in the choice of code longth of the structured construction, so this paper focuses on the the random construction algorithm of PEG(Progressive Edge Growth) and the improved algorithm which is based on the PEG algorithm. In this paper, by combining PEG with ACE(Approximate cycle EMD) algorithm to construct the LDPC codes of the NGB-W system, and in ordor to verify the constructed LDPC codes’ performance this paper simulate it by using MATLAB, and compare performance with the LDPC codes of the DVB-T2 system in the same simulation conditions. Then we find that the high rate LDPC codes constructed in this paper are superior to the LDPC codes in DVB-T2 system.