Abstract. The performance of free-space optical (FSO) communication systems based on avalanche photodiodes (APDs) is investigated over the aggregated double generalized gamma (double GG) fading channels. The approximate average bit error rate (ABER) expression is theoretically derived in terms of the double GG distributions under moderate and strong turbulent atmospheric conditions considering thermal noise and shot noise. The union bound and Hermite polynomials are then used to estimate the ABER performance of M-ary pulse-position modulation (PPM)-based systems and orthogonal frequency division multiplexing scheme (OFDM)-based systems. The ABER performance is studied with different receiver noise temperatures, modulation orders, turbulence strengths, and average photon counts assuming plane wave and spherical wave propagations. The results show that adopting an optimal average APD gain affected by the receiver temperature minimizes the ABER value for both wave propagations. In addition, the present APD-based system offers better ABER performance than that of a PIN-based FSO system over the double GG fading channels at two receiver noise temperatures of 200 and 400 K for both the PPM and OFDM schemes. We provide a reference for FSO system design.

中文翻译：

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基于雪崩光电二极管检测器的双广义伽马衰落通道上自由空间光学系统的平均误码率性能

摘要。研究了基于雪崩光电二极管 (APD) 的自由空间光 (FSO) 通信系统在聚合双广义伽马 (双 GG) 衰落信道上的性能。近似平均误码率（ABER）表达式是根据考虑热噪声和散粒噪声的中强湍流大气条件下的双GG分布在理论上推导出来的。然后使用联合边界和 Hermite 多项式来估计基于多进制脉冲位置调制 (PPM) 的系统和基于正交频分复用方案 (OFDM) 的系统的 ABER 性能。假设平面波和球面波传播，使用不同的接收器噪声温度、调制阶数、湍流强度和平均光子计数来研究 ABER 性能。结果表明，采用受接收器温度影响的最佳平均 APD 增益可使两种波传播的 ABER 值最小化。此外，对于 PPM 和 OFDM 方案，在两个 200 和 400 K 的接收机噪声温度下，当前基于 APD 的系统在双 GG 衰落信道上提供比基于 PIN 的 FSO 系统更好的 ABER 性能。我们为 FSO 系统设计提供参考。