Handover rates in cellular systems: towards a closed form approximation

Handover decision algorithms determine when a mobile wireless terminal should discontinue communication on the existing channel and begin communication on a new channel. Much work, both analysis and simulation, has been published on the expected number of handovers per cell boundary crossing. They are case specific; the analytic results require lengthy numerical solutions. No exact or even approximate closed form algebraic expressions are available. This paper calculates via simulation the expected number of handovers that occur as a user moves between two base stations. Through careful experimental investigation we provide a simple closed form approximation that is a function of base station separation, propagation characteristics including the path loss exponent and standard deviation of log-normal shadowing, and the amount of averaging used on the signal measurements. It is shown to be very good over the range of interest