A Fuzzy Adaptive Soft Handover Scheme Supporting Four Active Sets

Load imbalance between cells caused by random user distribution is a common issue in cellular systems, which often leads to traffic congestion. This can be alleviated by embedding a load balancing strategy into the handover scheme to dynamically reallocate load between neighbouring cells. A fuzzy adaptive soft handover scheme that can support four active set size is presented in this paper. In this paper, three fuzzy systems for radio link: addition, removal and replacement events are used and tuned to adapt to the soft handover thresholds and time hysteresis efficiently, depending upon the loads of the cells in user´s active set. Simulation results show that the new fuzzy algorithm alleviates congestion and provides improved system performance in terms of both lower blocking probabilities and higher system capacity.