浅海水声信道中QC-LDPC码性能研究

Performance analysis shallow water of QC-LDPC codes over acoustic channels

针对大起伏、强多途、窄带宽的浅海水声信道需采用码长短、性能好、易于实时处理的信道纠错码技术才能提高水声通信系统可靠性的问题，提出了准循环低密度奇偶校验（QC-LDPC）码作为浅海水声信道的信道纠错编码方案。建立了QC—LDPC码在水声信道中的仿真模型，采用BP译码算法，在典型3径浅海水声信道中就码率、围长等参数对误码率的影响进行了仿真，比较了其在不同海洋信道条件下的性能，在厦门港浅海域典型水声信道模型下，仿真研究了QC-LDPC码的性能。结果表明编码复杂度较低的．QC—LDPC码，性能接近于复杂度高、随机构造的（3，6）-LDPC码，在水声通信中具有良好的应用前景。

Considering that a shallow water acoustic （SWA） channel is characterized by rapid time-dispersive fading, muhipath and narrow bandwidth, which has to use the error correcting code technique with short code length, good performance and easy implementation to improve the reliability of its communication system, the quasi-cyclic low density parity check （QC-LDPC） coding as an error correction coding scheme was applied to SWA channels. A system simulation model including QC-LDPC codes for the SWA channels was built. With the decoding algorithm of belief propagation （ BP）, the performance of the system was simulated over a typical three-muhipath SWA channel under different code rates and girths. The performance comparison of QC-LDPC codes in different SWA channels was presented. A channel model was established according to the characteristic of the SWA channel environment in Xiamen harbor. The model was used to simulate the performance of QC-LDPC codes. The simulation results show that simple QC-LDPC codes can achieve almost the same performance of the random （3, 6 ）-LDPC codes, which proves the effectiveness and the good application prospects of QC-LDPC codes in SWA communication.