Link Quality Oriented Proactive Vertical Handover in Heterogeneous Wireless Networks

Effective link-layer trigger mechanism can significantly influence the handover performance and determine whether the handover completes successfully. The predictive handover framework that employs the required handover time and predicted signal power level to generate link trigger was proposed. Because this scheme doesn´t consider the moving condition of the mobile terminal (MT), it would increase unnecessary handover times when MT moves in low speed or changes moving direction. In this paper we propose an improved Link_Going_Down (LGD) trigger scheme-timetable mapping link trigger (TMLT) scheme. It constructs two timetables according to the required handover time and MT´s moving condition. By comparing and mapping the two different timetables, the LGD trigger time can be dynamically determined to minimize the link trigger costs, including the unnecessary handover probability and resource consumption.