Performance Research Of Bit Interleaved Coded Modulation With LDPC Codes For OFDM Systems

With the development of the wireless communication technology,people have put forward higher demand on the capacity of system and the quality of services.The request of broadband high-speed data communication service is increasing constantly.As one of the important means of anti-jamming technology, channel coding plays an important role in the field of wireless communication.Low Density Parity Check (LDPC) codes first discovered by Gallage in 1962 with the sparse check matrix have become a hot spot of research in the area of error correcting codes. Orthogonal Frequency Division Multiplexing (OFDM) technology with the characteristics of anti-multipath interference and frequency selective fading resistance,high bandwidth efficiency,can be applied to high-speed data transmission in multi-path environment and frequency selective fading channel. The Bit Interleaved Coded Modulation (BICM) integrated with the technology of OFDM (named BICM-OFDM system) becomes a prosperous scheme for realizing rapid and secure data transmission.In this dissertation,we focuses on the decoding algorithm for LDPC codes and the performance research of Bit Interleaved Coded Modulation with LDPC codes for OFDM Systems.We first introduce the background and the basic theory of LDPC codes,analyze the structure of LDPC codes,encoding and decoding algorithms, implementation of LDPC coeds with its application.At the same time,we simulate the performance of various BP decoding algorithm in MATLAB. Finally,introduce the theory of BICM and OFDM and propose a lower complex system that combining BICM-OFDM and LDPC.Theoretical analysis indicates that the system can maintain efficient and reliable communication while decrease the implementation complexity.Simulations with BICM-OFDM system respectively based on LDPC codes,Turbo codes and BCH codes confirm the theoretical analysis and show that simplified BICM-LDPC-OFDM system gets higher quality performance over fading channels.