Throughput Analysis of Incremental Redundancy Hybrid ARQ for FSO-Based Satellite Systems

This paper studies the error-control protocol design for free-space optical (FSO) burst transmission in satellite communication systems. Specifically, we model and analyze the throughput performance of LEO-to-ground FSO systems over atmospheric turbulence channels when incremental redundancy hybrid automatic repeat request (IR-HARQ) protocols, which combine rate-compatible punctured convolutional (RCPC) code and sliding window ARQ, are employed. For this purpose, the time-varying behavior of atmospheric turbulence channels is first captured by a finite-state Markov chain. Then, the channel model is used to develop the burst loss model for IR-HARQ in order to analytically derive the system throughput. The results quantitatively show the impact of atmospheric turbulence on the throughput performance and support the optimal selection of system parameters. Monte Carlo simulations are also performed to validate the accuracy of theoretical derivations.