A layer-2 trigger to improve QoS in content and session-oriented mobile services

In present wireless networks, mobile users frequently access continuous and session-oriented Internet services. During the handover, the management of session-related information introduces additional overheads and delays, due to context transfer procedures. Such delays may affect the QoS perceived by mobile users, making more difficult to realize seamless handover procedures. In this paper, we propose a framework to design a layer-2 trigger on the mobile node that intelligently activates the Context Transfer Protocol (CTP). Our proposed solution is based on methods to forecast the handoff time of the mobile node and the access router that will handoff the connection, and a model to estimate the time needed to complete the context transfer procedure. We show that the forecasting algorithm is stable, is able to effectively avoid the ping-pong effect, and converges both for simple and complex trajectories, typical of urban regions. We also evaluate the performance of CTP in the real case of a GSM network.