A STABLE DYNAMIC CALL ADMISSION POLICY WITH QoS GUARANTEE FOR MOBILE WIRELESS NETWORKS

Abstract

Call admission control is one of the key elements in ensuring the quality of service in mobile wireless networks. Traditional trunk reservation policy and its numerous variants give preferential treatment to the handoff calls over new arrivals by reserving a number of radio channels exclusively for handoffs. Such schemes, however, cannot adapt to changes in traffic pattern due to the static nature. In this dissertation, work has been done on a newly proposed stable dynamic call admission control policy (SDCA), which maximizes the radio channel utilization subject to a predetermined bound on the call dropping probability. This policy is adaptive to wide range of system parameters and traffic conditions due to its dynamic nature. The control is stable under varying traffic conditions. The admission policy is stochastic, thus spreading new arrivals evenly over a control period, and resulting in more effective and accurate control. This policy takes into account the effects of limited channel capacity and time dependence on the call dropping probability which greatly improve the control precision. In addition, this policy uses local control algorithms based on strictly local estimations of the needed traffic parameters, without requiring the status information exchange among different cells, which makes it very appealing in actual implementation. In this dissertation, the performance of SDCA is compared with two other call admission policies (Trunk Reservation and Distributed Call Admission policy) through simulation. Results show that SDCA scheme steadily satisfies the hard constraint on call dropping probability while maintaining a high channel throughput. The simulation program has been written in C++ language using an event oriented approach. The results have been obtained by running the program on a Pentium-III machine with windows 98 operating system