Fuzzy logic adaptive handoff algorithm

A handoff algorithm referred to as the fuzzy adaptive averaging-interval and hysteresis-threshold handoff (FAAH) is introduced. The design of the algorithm is intended to be used under a lognormal fading environment. The algorithm consists of two fuzzy logic controllers. The first controller takes into account the signal variation and the need to change the averaging interval (AVG) accordingly. The second controller dynamically adapts the hysteresis level (HYS) with the signal differences between two stations. Conventional algorithms with fixed signal averaging interval and/or fixed hysteresis level lack the flexibility under the changing (cellular) mobile environment. The FAAH is designed to strike a balance among handoff frequency, averaging delay, and the probability of lost calls. Four experiments were performed: constant AVG and HYS, fuzzy controls on AVG and constant HYS, fuzzy controls on HYS and constant AVG, and FAAH. The experimental results demonstrated that FAAH enhances the system handoff performance over conventional algorithms by about 50%