Throughput and Delay Performance of Cooperative HARQ in Satellite-HAP-Vehicle FSO Systems

This paper addresses the link-layer error-control solutions of high platform altitude (HAP)-aided relaying satellite free-space optical (FSO) systems for the Internet of Vehicles. Specifically, we propose a design of cooperative incremental redundancy (IR) hybrid automatic repeat request (HARQ) protocol to mitigate the transmission errors over the turbulence fading channels. The performance metrics, including average throughput and average frame delay, are analytically derived. The numerical results confirm the effectiveness of our proposed cooperative IR-HARQ protocol in FSO-based satellite-HAP-vehicle systems and support the proper selection of parameters. Monte-Carlo simulations are also performed to validate the correctness of theoretical results.