Study about LDPC codes applied in underwater laser communication

In order to study the performance of low density parity check (LDPC) codes applied in an underwater laser communication system,its bit error rate was simulated by means of soft-decision decoding algorithm.A model of underwater laser communication channel was introduced,and then the encoding and decoding algorithm of LDPC codes was studied.For a certain code length and modulation order,the bit error rate can be reduced to 10-5 with the signal photon number ns increase.The simulation results show that the bit error rate of the system can be improved obviously by means of LDPC soft-decision decoding based on the output soft information of the photo detector.