激光脉冲云层传输时间扩展与信道均衡

Temporal Dispersion of Laser Pulse through Clouds and Channel Equalization

云层粒子对激光的多次散射引起激光脉冲产生时间扩展,造成接收信号出现码间串扰。首先建立了带均衡滤波的云层激光通信链路信道模型;然后使用蒙特卡洛光线追踪法得出了云层信道在不同光学厚度下的脉冲时间响应特性;并推导出考虑码间串扰时的系统误码率计算模型。对不同云层光学厚度下,不使用均衡滤波和使用均衡滤波时的信噪比与系统误码率间的关系进行了仿真与分析,发现使用均衡滤波能有效地对云层信道多次散射效应的影响进行抑制。

The multi-scatterings caused by cloud particles induce temporal dispersion of laser pulse, which leads to inter-symbol interference （ISI） in the received signal. The channel model with equalization filter of laser communication link through clouds was proposed; the temporal response of laser pulse for the different optical thicknesses was obtained by Monte Carlo ray tracking （MCRT） method; the bit error rate （BER） model was deduced in consideration of ISI. The relationships between BER and signal-to-noise rate （SNR） were simulated at different optical thicknesses, with and without equalization filter. The simulated results show that equalization filter can mitigate the effect of multi- scatterings of cloud channel obviously