A shortest job first (SJF)-like scheme for efficient call handoff in mobile networks

In cellular networks, when a mobile station (MS) with an ongoing call moves from cell to cell, a handoff process takes place. Specifically, the serving base station, which the MS intends to leave, communicates with the target base station, which the MS intends to join, for the latter to reserve a channel. Since there can be many MSs requiring handoff at the same time, the serving base station should give priority to those with less remaining time τ in the cell, or else the call will be force-terminated. Many schemes have been proposed to provide such a priority system. However, those schemes depend on a certain threshold τ_h, treating every MS below it the same. In other words, if τ_h= 5 seconds, and there are two MSs with remaining times τ=4 and τ=1, the BS will handoff the former first if it requested the handoff first. In other words, those schemes implement a sort of FCFS queueing discipline. But such a discipline could of course result in the termination of the call of the latter if it leaves the cell before the 1 seconds. The present scheme cures this problem. Namely, it treats each MS individually, giving priority to the one with the minimum τ. Actually, it sorts the MSs requesting handoff based on their remaining times, performing handoff to the one with the lowest τ. In other words, the scheme implements a sort of shortest job first (SJF) queue.