The Reasearch Of Error Correction Based On Ldpc With High Bit Erroe Rate Channel

As the channel quality of high bit error rate channel is poor, so it is always added a lot of redundant information to complete the correction process. Since low rate LDPC code is a kind of channel coding with high performance and is applied well to the high bit error rate channel, so how to design low code LDPC code is the main research in this paper.Firstly, multi-edge type LDPC code is adopted to design low rate LDPC code since the conditions of designing low rate LDPC code and limitations of irregular LDPC code are analyzed. Secondly, the structure of multi-edge type LDPC code to decode well is described in detail, including cascaded constructions for degree one variable nodes. Density evolution algorithm is realized with C programming language by analyzing density evolution and convergence of cascaded constructions for degree one variable nodes. The degree distributions of the low code rate LDPC code are optimized and threshold are calculated with density evolution algorithm. Lastly, check matrixes of LDPC code are generated according to the degree distributions.The low rate LDPC codes with code rate0.02,0.04,0.06and0.08can be obtained through density evolution and structure check matrix algorithm of multi-edge type LDPC code. BPSK modulation and additive white Gaussian noise channel are adopted and the simulation system of channel coding is realized with C language programming. Through the system simulation, error correction performance of LDPC codes with code rate0.02,0.04,0.06, and0.08are all greater than90%, which are very close to the Shannon Limit.In this paper, the process of designing low rate LDPC code is simple and general, which has an important guiding significance. It makes up for the deficiency of designing low rate LDPC code and is advantageous to the reliable transmission of high bit error rate communication environment in this paper.