针对深空光通信中现有的多脉冲位置调制(MPPM)方案存在星座点利用率较低及位置选择有待优化的问题, 通过比较不同的MPPM方案星座点间的平均汉明距离及信号脉冲位于相邻时隙的概率, 提出一种抗时延抖动能力更强的MPPM星座映射方案。基于现有的串行级联脉冲位置调制(SCPPM)译码算法, 推导了串行级联MPPM(SCMPPM)迭代译码算法。仿真结果表明: 该方案的性能比现有方案更优, 不仅能够使通信系统保持较高的信息传输速率, 还可以降低MPPM星座点间符号串扰(ISI)及时隙串扰(ITI)的概率, 提高通信系统抗时延抖动的能力。

In view of the existing multi-pulse position modulation (MPPM) schemes in deep space optical communication, the constellation points have a low utilization rate and the location selection needs to be optimized. By comparing the average hamming distance between constellation points of different MPPM schemes and the probability of signal pulses in adjacent time slots, an MPPM constellation mapping scheme with stronger anti-delay jitter capability is proposed. Based on the existing serial concatenated pulse position modulation(SCPPM) decoding algorithm, a SCMPPM iterative decoding algorithm is derived. Simulation results show that the performance of this scheme is better than the existing schemes. It not only enables the communication system to maintain a high information transmission rate, but also reduces the probability of inter-symbol interference(ISI) and inter-slot interference(ITI) between MPPM constellations, thereby improving the anti-delay jitter capability of communication system.