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从大气激光通信信道模型出发,结合大气激光通信特殊的调制方式,利用接收解调软判决序列的后验概率信息,导出大气激光通信自适应系统中低密度奇偶校验码(LDPC)的识别算法公式。仿真结果表明,当识别正确率为0.8时,在强湍流条件下,算法公式比传统算法性能提高约1.2dB;在弱湍流条件下,算法公式比传统算法性能提高约1.5dB;并且随着码率的降低和码长的增加,识别成功率均有提高。因此,所提算法公式能够进一步抑制大气湍流影响,提高系统性能。
Based on atmospheric laser communication channel model, combined with the special modulation method of atmospheric laser communication, the recognition algorithm of low density parity check code (LDPC) in atmospheric laser communication adaptive system is derived by using the posterior probability information of demodulation soft decision sequence. formula. Simulation results show that when the recognition accuracy is 0.8, under the condition of strong turbulence, the performance of the algorithm is improved by about 1.2dB compared with that of the traditional algorithm. In weak turbulence, the performance of the algorithm is 1.5dB higher than that of the traditional algorithm. The decrease of the rate and the increase of the code length increase the success rate of recognition. Therefore, the proposed algorithm can further suppress the influence of atmospheric turbulence and improve the system performance.