An effective algorithm for construction of LDPC codes

Based on the analysis of the cycle structure of quasi-cyclic codes, an effective algorithm for LDPC codes’s construction is presented in this paper. The influence of cycle structure on the BER performance of LDPC codes is analyzed. We also propose a construction algorithm of LDPC codes which describes the parity-check matrix with a base matrix and a shift matrix. Simulations show that the code we construct has as good BER performance as that by PEG algorithm at the same codeword length and code rate. For having quasi-cyclic structure, the code has lower encoding complexity and can be implemented with a set of shift registers.