ADAPTIVE AVERAGING METHODOLOGY FOR HANDOFFS IN CELLULAR-SYSTEMS

The purpose of this paper is to show how information in signal strengt h measurements can be exploited to improve the quality of handoff deci sions, for both large and small cells, Averaging of signal strength fl uctuations is required, This leads to the following tradeoff problem f or the averaging interval for the signal strength measurements. If the interval is too short, the fading fluctuations are not sufficiently s moothed out, If the interval is too long, delay in handoff increases, With this tradeoff in mind, we present a method to adaptively change t he averaging interval, The method is based on estimating the maximum D oppler frequency, f(D), as a means to obtain mobile velocity, the hey to the tradeoff. A method used for estimating f(D) from the squared de viations of the signal envelope is outlined, Exact analysis for the f( D) estimate as a function of squared deviations of the logarithmically compressed signal envelope in Rayleigh fading is presented, An extens ion of the algorithm for robustness in a Rician fading environment is given, Sensitivity issues of the estimates are considered, An adaptive scheme for optimal averaging is outlined.