联合效应影响下脉冲位置调制的大气光多输入多输出系统的误码率

Bit Error Rate of Atmospheric Optical Multiple Input Multiple Output System with Pulse Position Modulation Under Influence of Combined Effect

研究了大气衰减、湍流、瞄准误差和空间相关性共同作用的联合效应对大气无线光多输入多输出(MIMO)系统误码率(BER)的影响。利用泊松计数模型和指数相关模型,推导了联合效应下脉冲位置调制(PPM)的最大似然检测准则;采用Wilkinson近似方法推导了大气光MIMO系统BER的上界;仿真分析了联合效应中各因素对大气光MIMO系统BER的影响。结果表明,当大气衰减确定时,空间相关性对系统BER的影响最显著,抖动误差次之,湍流影响最小;当大气衰减变化时,传输距离是影响BER的最重要因素;另外,空间分集对系统性能的改善仅在信道独立时具有较好的效果,信道相关时效果并不明显。

The combined effect of atmospheric attenuation, turbulence, pointing errors, and spatial correlation on the bit error rate (BER) of an atmospheric wireless optical multiple input multiple output (MIMO) system is investigated. The maximum likelihood detection criterion of the pulse position modulation (PPM) under the combined effect is derived via a Poisson counting model and an exponential correlation model. On this basis, the upper bound of the BER of the atmospheric optical MIMO system is derived via the Wilkinson approximation method. In addition, a simulation experiment is used to further analyze the influences of the various factors in the combined effect on the BER of the atmospheric optical MIMO system. The results show that when the atmospheric attenuation is constant, the spatial correlation has the most serious impact on the BER of the system, followed by the jitter error and the atmospheric turbulence. In contrast, the transmission distance is the most important factor influencing the BER of the system when the atmospheric attenuation is changeable. In addition, the performance improvement of the system resulting from the spatial diversity only works well when the channels are independent, and this improvement is not obvious when the channels are correlated.