Cross-layer management of radio resources in an interactive DVB-RCS-based satellite network - invited paper

Recently, the request for multimedia broadband services via satellite has been rapidly increasing. We envisage a group of terminals that have to transmit (uplink) to a Network Control Center (NCC) via a geostationary bent-pipe satellite; the NCC is interconnected to the Internet through a router. Terminals employ the DVB-RCS standard to communicate with the NCC. Due to both the intrinsic propagation delay and the presence of a lossy radio channel, the Transport Control Protocol (TCP) is particularly inefficient in the satellite scenario. Therefore, we propose a novel cross-layer mechanism where resources are allocated by the Medium Access Control (MAC) layer at the NCC depending on the TCP behavior at remote terminals. Moreover, the MAC layer can also intervene on the TPC data injection rate to avoid system congestion. Simulation results show that: (i) our scheme prevents the occurrence of TCP timeouts (due to the satellite network congestion), thus improving the utilization of radio resources; (ii) it reduces the mean file transfer time for ftp applications with respect to a classical allocation scheme. This paper has been carried out within A&TCP research group of the "SatNEx" NoE project (URL: www.satnex.org; contract No. 507052) belonging to the 6-th framework of the European Commission.