Design and performance evaluation of mechanisms for mobile-devices handoff forecast

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 over-heads 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 design a set of mechanisms (called CT-Trigger), which operate on the mobile node at different network layers and intelligently activate the context transfer in the framework of the Context Transfer Protocol. The proposed mechanisms provide methods to forecast the hand-off time of the mobile node and the access router that will hand off the connection, and an actuator to start the context transfer signaling. We show that the forecasting algorithm is stable and converges both for simple and complex trajectories, typical of urban regions; moreover, it is able to effectively avoid the ping-pong effect. We also present the design of the CT-Trigger.