Evaluating TCP Mechanisms for Real-Time Streaming over Satellite Links

Real-time streaming over satellite IP networks is challenging, since satellite links commonly exhibit long propagation delays and increased error rates, which impair TCP performance. In this context, we quantify the effects of satellite links on TCP efficiency and streaming video delivery. We investigate a solution-framework composed by TCP implementations which are expected to perform adequately in such environments. Furthermore, we study the supportive role of Selective Acknowledgments (SACK). Along with protocol performance, we also evaluate the impact of delayed acknowledgments. Our simulation results illustrate that most existing end-to-end solutions do not comply with the stringent QoS provisions of time-sensitive applications, resulting in inefficient bandwidth utilization and increased delays in data delivery. Finally, with the absence of a satellite-optimized TCP implementation for real-time streaming, we identify TCP Real as the most prominent solution, since it manages to alleviate most of the impairments induced by satellite links, sustaining a relatively smooth transmission rate.