Free space optical (FSO) communication channels are affected by fluctuations in irradiance due to atmospheric turbulence and pointing errors. Recently, a generalized statistical model knows as Málaga ( ) was developed to describe irradiance fluctuations of the beam propagating through a turbulent medium. In this paper, an approximate finite-series probability density function (PDF) for composite turbulence with pointing errors is verified. Considering multiple pulse-position-modulation (MPPM) with intensity modulation and direct detection, specific closed-form expressions for average symbol error rate (ASER) and outage probability are obtained. Moreover, asymptotic expressions for ASER and outage probability over the Málaga channel with pointing errors are presented. Finally, ASER and outage probability expressions are deduced in three turbulence regimes, strong, moderate, and weak. Therefore, simulation results are given to confirm the accuracy of the proposed expressions. The results show that the optimum beam divergence angle is 1 mrad for zero-boresight displacement and 2 mrad for nonzero-boresight at a distance of 1 km. By increasing the range to 5 km, atmospheric turbulence is found to have the dominant effect over boresight displacement. Moreover, the system performance at the optimized divergence angle is studied in terms of transmit power, normalized boresight, and link distance.

中文翻译：

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带有MPPM和非零视轴指向误差的马拉加湍流通道FSO系统的通用评估

自由空间光学（FSO）通信通道会受到由于大气湍流和指向误差引起的辐照度波动的影响。最近，一个广义的统计模型称为马拉加（ ）被开发来描述通过湍流介质传播的光束的辐照度波动。本文提出了一种用于复合材料的近似有限系列概率密度函数（PDF）验证了指向错误的湍流。考虑到具有强度调制和直接检测功能的多脉冲位置调制（MPPM），可以获得平均符号错误率（ASER）和中断概率的特定闭式表达式。此外，还给出了带有指向误差的马拉加通道上ASER和中断概率的渐近表达式。最后，在强，中和弱三种湍流状态下推导了ASER和中断概率表达式。因此，给出了仿真结果以确认所提出表达式的准确性。结果表明，最佳的光束发散角对于零视距位移为1 mrad，对于非零视距位移在1 km处为2 mrad。通过将范围增加到5公里，发现大气湍流对视轴位移具有主要影响。此外，还根据发射功率，归一化视轴和链路距离研究了在最佳发散角下的系统性能。