A Construction Method of LDPC Codes for Space Optical Communications Based on Protograph

In order to meet the requirements of low bit error-rate of the channel code in the space optical communication system, a construction method of low density parity check ( LDPC) codes with excellent performance is proposed based on protograph and quasi-cyclic expansion. It can be applied in high-speed encoding and decoding with efficient quasi-cyclic expansion. According to the proposed method, a LDPC ( 8832, 1472) suitable for the space optical communication system is constructed, in which the LDPC codes of the protograph perform very well. Simulation shows that the LDPC codes have superior error-correction performance and show no sign of error floor when the BER is in the order of 10-9, which are suitable for the long-distance space optical communication systems.