A Class of QC-LDPC Codes With High Performance and Low Complexity in Deep Space Communication

A class of QC-LDPC codes with high error performance and low complexity was proposed. Firstly, a global matrix M with extern Approximate Lower Triangular (eALT) method was designed. Each 1 in the global matrix M was replaced by a permutation matrix, and each 0 was substituted by a null matrix to reduce the number of small stopping set and error floor. Then, In order to lower the complexity of searching cyclic shift coefficient, a Zig-Zag based method was put forward, which uses a given formula to generate coefficient and does not need search by computer. At last, the linear encoding process was given with the proposed QC-LDPC. Simulation result shows that the proposed method can reduce the number of small stopping set, increase the minimum distance of LDPC codes, and achieve very low error floor with linear encoding complexity. What's more, the cyclic shift coefficient was generated by structured method.