Free-space optical (FSO) links are considered as a cost-efficient way to fill the backhaul/fronthaul connectivity gap between millimeter wave (mmWave) access networks and optical fiber based central networks. In this paper, we investigate the end-to-end performance of dual-hop mixed FSO/mmWave systems to address this combined use. The FSO link is modeled as a Gamma-Gamma fading channel using both heterodyne detection and indirect modulation/direct detection with pointing error impairments, while the mmWave link experiences the fluctuating two-ray fading. Under the assumption of both amplify-and-forward and decode-and-forward relaying, we derive novel closed-form expressions for the outage probability, average bit error probability (BER), ergodic capacity, effective capacity in terms of bivariate Fox’s $H$ -functions. Additionally, we discuss the diversity gain and provide other important engineering insights based on the high signal-to-noise-ratio analysis of the outage probability and the average BER. Finally, all our analytical results are verified using Monte Carlo simulations.

中文翻译：

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FSO / mmWave混合衰落信道下双跳系统的性能研究

自由空间光（FSO）链路被认为是填补毫米波（mmWave）接入网络与基于光纤的中央网络之间的回程/前程连接间隙的一种经济高效的方法。在本文中，我们研究了双跳FSO / mmWave混合系统的端到端性能，以解决这种组合使用的问题。FSO链路使用外差检测和具有指向误差的间接调制/直接检测建模为Gamma-Gamma衰落信道，而mmWave链路则经历了波动的两射线衰落。在同时进行放大转发和解码转发的假设下，我们得出了用双变量Fox表示的中断概率，平均误码率（BER），遍历容量，有效容量的新颖封闭形式表达式。 $ H $ -职能。此外，我们基于中断概率和平均BER的高信噪比分析，讨论了分集增益并提供了其他重要的工程见解。最后，我们的所有分析结果均使用蒙特卡洛模拟进行了验证。