TCP Performance Issues in Satellite and WiFi Hybrid Networks for High-Speed Trains

Abstract

GEO satellite communication systems are an efficient approach for broadband Internet provision on highspeed trains, but some work is still needed to allow a seamless service. In the railway scenario, satellite communications suffer from strong variations in the received signal power and need suitable solutions to deal with long channel disruptions due to tunnels. The approach envisaged in this paper is based on a hybrid network (satellite and terrestrial WiFi coverage) and a Vertical Handover (VHO) procedure to switch seamlessly from one segment to another whenever link quality degrades and a new segment is available. This paper deals with the TCP performance in the presence of VHOs (based on the IEEE 802.21 Media Independent Handover, MIH, standard) from the satellite to a terrestrial wireless segment and viceversa to cover tunnels. Details are provided for the adoption of MIH and MIPv6 in such a context, referring to the BSM standard. Design criteria for the WiFi coverage extension outside the tunnel are also presented. Finally, we have shown that TCP goodput behavior and convergence time can be improved by means of suitable accelerated TCP versions or using cross-layer methods.

Optimization of hybrid broadcast/broadband networks for the delivery of linear services using stochastic geometry

“…Such vehicles usually move out of the reach of conventional methods due to large distances and tunneling. This was investigated in [176], where a hybrid satellite/Wi-Fi model with vertical handover procedure is proposed. In the studied model, a train receiving satellite signal will switch to a fixed Wi-Fi access point when approaching a tunnel.…”

“…Distributed gap fillers [168,169] Sat/Wi-Fi Fixed AP [170][171][172]175] On-board AP [176] Cellular Broadband UC/MC…”

Proactive TCP Mechanism to Improve Handover Performance in Mobile Satellite and Terrestrial Networks

“…However there are several approaches to deal with disruption in connectivity issue like Delay/disruption tolerant Networking [17], Proxy enhancing Proxy (PEP) [16], Accelerated TCP [15], or combination of these approaches.…”