Call admission control in mobile cellular systems using fuzzy associative memory

In a mobile cellular system quality of service to mobile terminals (MTs) is measured by the probability of new call blocking P_b, and the probability of forced termination, P_ft. Since the available bandwidth in a cell is very limited, both P_b and P_ft cannot be reduced or avoided simultaneously. Usually keeping the P_ft below a designated level is accepted as the measure of quality of service. Admission of new calls is controlled to reduce P_ft. However, there are at least three parameters (new call arrival rate, mean duration of calls, and mobility of users) that can and change dynamically. Moreover, these parameters are related with P_ft via complicated nonlinear equations. Therefore, call admission control (CAC) for maintaining a desired value of P_ft is a very challenging task. No CAC algorithm has been reported in the past that can function well with dynamic changes to all these three parameters. We proposed an algorithm that addresses this issue. The new algorithm uses a fuzzy controller to adjust the call preblocking load value with the changing traffic parameters. The fuzzy controller makes use of fuzzy associative memory (FAM) to maintain the required QoS. The use of new system in dynamic traffic conditions is illustrated. Providing the required level of QoS, the algorithm also increases the channel utilization. The proposed CAC with FAM is compared and contrasted with previous CACs.