Performance of TCP Over Free-Space Optical Atmospheric Turbulence Channels

This paper presents an analytical study of the performance of transmission control protocol (TCP) over free-space optical (FSO) turbulence channels when the automatic-repeat request, selective-repeat (ARQ-SR) scheme is employed. Different TCP versions, including Tahoe, Reno, and selective acknowledgement, are considered. In the TCP throughput analysis, a three-dimensional Markov model is used. In addition, to analyze the joint effect of ARQ-SR and FSO turbulence channels in terms of both TCP throughput and energy consumption, a newly defined joint throughput-energy-efficiency parameter is analytically derived. In the numerical results, we discuss cross-layer design strategies for the selection of FSO system parameters and the ARQ-SR scheme in order to maximize the TCP throughput and to achieve the trade-off between the energy consumption and the throughput under various conditions of the FSO turbulence channel.