Analysis of handoff algorithms using nonstationary signal strength measurements

As an extension of their earlier work (see Proc. 1st Int. Conf. on Universal Personal Commun., Sept. 1992), which demonstrated the validity of the Poisson model for the specific case where the signal strength process is stationary, the authors present an analytic model for analyzing the performance of field-strength based handoff algorithms. The handoff process is related to level crossings of the difference between the received signal strengths from two base stations. The algorithm performance is derived by modeling the level crossings as Poisson processes with time-varying rate functions. This model is seen to yield results that agree with those obtained from simulations over the range of algorithm parameters that is of practical interest. These results can be used to determine the averaging interval and hysteresis level that achieve the optimum tradeoff between the number of unnecessary handoffs and the delay in handing off