Effect of SNR margin in TCP performance for HSDPA via GEO satellite

This paper investigates the effect of the Signal to Noise Ratio (SNR) margin, h, that is used to compensate for the long propagation delay experienced in Satellite High Speed Downlink Packet Access (S-HSDPA) air interface. Satellite Systems are expected to complement the terrestrial access network and work with the same core network. The geostationary bent-pipe satellite has been considered for this work. A cross-layer study of the effect of the physical layer on the performance of TCP based traffic was conducted by varying margin values. A 3-state markov channel model has been used for this work. Our aim is to investigate the impact of the margin on TCP performance and recommend the optimal margin for this channel model. We also investigate if the TCP performance for varying margins will remain consistent for different environment and TCP versions.