Due to the limitation of the radio spectrum, future wireless systems will use micro/pico-cellular architectures in order to provide a higher capacity. Because of the small coverage area of micro/pico-cells, handoff events will occur at a much higher rate as compared to today's macro-cellular systems. Frequent handoff and mobility might result in rapid changes and overloads in the traffic conditions of radio cells. Thus, call admission control functions are required to keep the probability of a congested radio state low.
In this paper, we present a call admission control scheme combined handoff queue and bandwidth reservation to minimize the handoff failure probability while preserving high network resource utilization for multimedia communication in mobile multimedia cellular network. Our approach differentiates the new call and the handoff, considers the guaranteed and best effort traffic for multimedia application, and reserves the bandwidth in the neighboring cells allowing queuing of handoff requests. In the proposed call admission control scheme, the total bandwidth of the radio cell is divided into reserved fraction and non-reserved fraction, and the reserved fraction is used exclusively for the handoff. New calls are accepted if some bandwidth is available in non-reserved fraction, otherwise is rejected. Handoffs are accepted if some bandwidth is available in the sum of non-reserved fraction and reserved fraction, otherwise is queued and is accepted or rejected depending on the queuing delay when the bandwidth is available later.
For the purpose of evaluating the performance of our approach, we have simulated our scheme and other three generic schemes, and have compared their performances. The other three generic schemes are no control scheme, bandwidth reservation scheme and only handoff queuing scheme. The simulation results show that our approach is more efficient in minimizing the handoff failure probability than other schemes.