Internet access in hybrid terrestrial and satellite mobile communication systems

Satellite systems will play a significant role in the provision of broadband transmissions to mobile users. This paper deals with a hybrid network architecture with a geostationary satellite for downlink high bit-rate transmissions and a terrestrial 3G return link both to account for the limited power available on mobile terminals and to exploit the lower propagation delays of the terrestrial path. We have considered that both TCP traffic and UDP one is destined to a dual-band mobile terminal. A suitable routing configuration has been employed to support this hybrid network that has been implemented in a simulator under the ns2 environment. The obtained results have permitted to compare the performance of different TCP versions (i.e., NewReno, SACK and Westwood) also including the possibility to adopt ARQ on the satellite link. We have shown the TCP goodput advantages of the hybrid scenarios with respect to the case where both downlink and uplink are via satellite. Finally, we have obtained that TCP Westwood permits to achieve the best performance.