Free space optical (FSO) communication has established a reputation for itself capable of delivering high-speed data services over long distances without exhausting radio frequency (RF) resources. FSO communication can be considered in different network scenarios, including inter-satellite/deep-space links, ground-station/vehicles, satellite/aerial links, and terrestrial links. It is expected to be one of the key enabling technologies for the next generation of 6G wireless networks. Nevertheless, despite the great potential of FSO communications, its performance suffers from various limitations and challenges: atmospheric turbulence, clouds, weather conditions, and pointing misalignment. The error-control solutions, including physical layer (PHY) and link-layer methods, aim to mitigate the transmission errors caused by such adverse issues. While the existing surveys on error-control solutions in FSO systems primarily focussed on the PHY methods, we instead provide a review of link-layer solutions. In particular, we conduct an extensive literature survey of state-of-the-art retransmission protocols, both automatic repeat request (ARQ) and hybrid ARQ (HARQ), for various FSO communication scenarios, including point-to-point terrestrial, cooperative, multi-hop relaying, hybrid FSO/RF, satellite/aerial, and deep-space systems. Furthermore, we provide a survey of recent literature and insightful discussion on the cross-layer design frameworks related to link-layer retransmission protocols in FSO communication networks. Finally, the lessons learned, design guidelines, related open issues, and future research directions are exposed.

中文翻译：

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FSO 通信中基于链路层重传的错误控制协议：调查


自由空间光 (FSO) 通信因其能够在不耗尽射频 (RF) 资源的情况下长距离提供高速数据服务而享有盛誉。 FSO通信可以在不同的网络场景中考虑，包括卫星间/深空链路、地面站/车辆、卫星/空中链路和地面链路。预计它将成为下一代6G无线网络的关键使能技术之一。然而，尽管 FSO 通信潜力巨大，但其性能仍受到各种限制和挑战：大气湍流、云、天气条件和指向偏差。错误控制解决方案，包括物理层（PHY）和链路层方法，旨在减轻此类不利问题引起的传输错误。虽然 FSO 系统中错误控制解决方案的现有调查主要集中在 PHY 方法，但我们对链路层解决方案进行了回顾。特别是，我们针对各种 FSO 通信场景（包括点对点地面、协作、多跳中继、混合 FSO/RF、卫星/航空和深空系统。此外，我们还对最近的文献进行了调查，并对与 FSO 通信网络中的链路层重传协议相关的跨层设计框架进行了深入的讨论。最后，揭示了经验教训、设计指南、相关的开放问题和未来的研究方向。