Encoding And Decoding Of LDPC Codes And Its Application In OFDM Systems

Channel coding,which is a very important part of digital communications system and computer systems, can bring coding gain, and save valuable power resources. LDPC code is a sparse check matrix based on linear block error-correcting codes, low complexity iterative decoding algorithm, with performance approaching the Shannon limit. LDPC codes with its superior performance, full parallel iterative decoding structure, decoding complexity linear growth, ease of hardware implementation of a series of advantages in wireless communication, has been widely applied in deep space communications and storage industries and many other fields, in many fields it has a wide range of applications, such as space communications. Satellite communications. Optical fiber communication. Personal communication systems, ADSL, WLAN, etc.. As the many advantages of LDPC codes, making it a reliable transmission of information has an excellent prospect, become the most watched channel coding areas of research focus.The next generation of mobile wireless communications goal is to achieve nothing not to, high quality, high-speed mobile multimedia transmission. To achieve this goal, we need to overcome many technical difficulties. Mainly for the wireless fading channel multipath propagation and scattering caused by signal fading, multipath delay and large inter-symbol interference caused by Li. Orthogonal frequency division multiplexing (OFDM) technology will be divided into many orthogonal subchannels channel, data can be transmitted in parallel in the sub-channel, high-speed transmission that can be done. Subcarriers in order to avoid errors in the transmission, error correction coding techniques are used in many OFDM systems. Low Density Parity Check (LDPC) error correcting codes in the field has been widespread attention.In this paper, LDPC codes used in OFDM system, the following aspects of the study:1) LDPC decoding using BP algorithm, the number of iterations on the system performance and the variation of the number of iterations.2) LDPC codes and Turbo codes applied to OFDM systems applied to compare the performance of OFDM systems. LDPC codes practical to go quite a long way, although the long code performance when the LDPC code can go beyond the Turbo code, but the short code much worse than the Turbo code. LDPC codes in this paper only the performance of OFDM systems to do the analysis of the shallow, how to improve its performance is still a problem worthy of study.