Analytical-numerical study of the handoff area sojourn time

In cellular systems there normally exists an overlap cell coverage area (area covered by two or more base stations) which has valuable practical applications: soft handoff is an important feature of CDMA systems and in hard handoff the overlap area permits the handover request queuing as a handover prioritisation scheme. While an extensive research effort has been done to model the terminal residence time in a cell and the channel holding time, the sojourn time in the overlap area is a topic that still requires further study. In this paper we propose a model of the sojourn time in the overlap area along with a novel numerical method to derive its probability distribution. The obtained results show that the common assumption of exponential distribution for this time is not suitable, whereas it can be satisfactorily fitted by the hyper erlang distribution.