We study the performance of a selection combining (SC) receiver operating over independent but non-identically distributed log-logistic ($\mathcal{LL})$ fading channels. We first characterize the statistics of the output instantaneous signal-to-noise ratio (SNR) of the SC receiver. Based on the SNR statistics, we derive exact analytical expressions, in terms of multivariate Fox H-functions, for the outage probability, the average bit error rate, and the ergodic capacity. We also derive exact expressions for such performance measures when all channels are independent and identically distributed, as a special case. Furthermore, we deduce simplified asymptotic expressions for these performance metrics assuming high values of average transmit SNR. To demonstrate the applicability of our theoretical analysis, we study the performance of an SC receiver in underwater optical wireless communication systems. Finally, we confirm the correctness of the derived analytical results using Monte Carlo Simulations.

翻译：我们研究了工作于独立但非同分布的**对数-逻辑（$\mathcal{LL}$）** 衰落信道上的选择合并（SC）接收机的性能。首先，我们刻画了SC接收机输出瞬时信噪比（SNR）的统计特性。基于该SNR统计特性，我们利用多元Fox H函数推导了中断概率、平均误码率以及遍历容量的精确解析表达式。作为特例，当所有信道独立同分布时，我们还给出了这些性能指标的精确表达式。此外，我们假设平均发射SNR较高，推导了这些性能指标的简化渐近表达式。为证明理论分析的适用性，我们研究了SC接收机在水下光无线通信系统中的性能。最后，我们通过蒙特卡洛模拟验证了所推导解析结果的正确性。