QoS-guaranteed call admission scheme for broadband multiservices mobile wireless networks

摘要

In wireless networks, bandwidth is extremely valuable resource. Therefore, an effective call admission control is urgent for bandwidth allocation with the occurrence of handoff increasing. The main challenges with multiple types of traffic are that each has its own requirements of bandwidth, traffic characteristic, QoS guarantee and handoff rate. Moreover, the computational complexity is another challenge. To meet these challenges, we set up a fictitious stochastic model to study the actual system so as to avoid coping with the complex multiple dimensions stochastic problem. On one hand, it can turn the multiple steps of state transition into single step, which is a necessary condition for ideal birth-death processes. On the other hand, it can provide a simple and effective method to compute a little larger approximation of the call dropping probabilities for multiple services, which facilitate our estimation for the acceptance ratio vector subject to QoS requirement. In addition, the boundary conditions are also considered in order to improve the control precision. Furthermore, a fast numerical method has been found to decrease the computation complexity greatly. As a result, we get an effective multiservices dynamic call admission scheme called EMDCA to adapt for multiple types of services in broadband wireless networks. Numerical results of simulation show that our scheme steadily satisfies the hard constraint on call dropping probability of multiservices while maintaining a high channel throughput.