PERFORMANCE EVALUATION OF ENHANCED HANDOFF IN WCDMA CELLULAR NETWORK USING AN INTELLIGENT SCHEME
Keywords:Soft handoff, signaling overhead, radio link events, Fuzzy Inference System
One important measure for signaling overhead in Wide Band Code Division Multiple Access (WCDMA) is the number of handoff per unit time. In particular, the link addition and release for the soft handoff are crucial for the amount of signaling load in the network. Frequent Soft handoff cause more signaling traffic and channel utilization wastage. Therefore it is desired that handoff should be done only when it is necessary. Besides, handoff decision should be precise by taking into account all possible options and considering the best one. In this paper, a Fuzzy Logic based soft handoff decision algorithm was developed, considering the user mobility to suppress the ping-pong effect. By using GPS positioning, the developed algorithm intelligently adds a hysteresis parameter associated with distance between the mobile and surrounding base stations and a hysteresis parameter associated with the mobile heading direction in soft handoff events. The performance was verified in a MATLAB simulation by applying the developed intelligent soft handoff algorithm to a WCDMA system in Onitsha urban city. The result shows that by using the developed algorithm, soft handoff number is decreased by 33.9% compared to the traditional algorithm.