Investigation On Network Selection And Call Admission Control Policy In Heterogeneous Wireless Networks

With the rapid development of wireless communications, the various wireless networks will conxist. In order to realize the final goal of future wireless communications, accommodate mobile users increased enormously and offer multimedia traffic services with high quality, different wireless networks overlaid each other must be integrated to cooperate and form an uniform,based on ip protocol heterogeneous system.The radio resource management is a key technology and a research hotspot in the heterogeneous system. It includes many sub-areas such as call access control, handoff control, layer selection, load control, power control, packet schedule, capacity analysis and so on. Firstly, this thesis discussed the mode and structure of heterogeneous network, researched on two aspects: multi-object handoff and the call admission control (CAC), and finally, proposed realizable schemes.Firstly,the thesis reserched the handoff process. Conclued the current handoff algorithm. In order to overcome the shortcome of the old algorithms,we proposed a multi-object handoff algorithm which is dynamic adaptive. .The algorithm is based on an operational theory, which divides a complex problem into hierarchiescan, make the judgment process more clear and reasonable , also it can change the weight dynamic. So it can make judgment for complex multi-object handoff problem.In order to further increase the utilization of the wirless system resource,and protect the fair of user's QoS,In the second part of the thesis,The algorithm of call admission control is reserched. Based on the Optimal Guard Channel Policy, A seamless-QoS-oriented CAC scheme is proposed as an optimization problem aiming to minimize the overall grade of service (GoS)The model is build on GPRS and WLAN system.Accordingly,the optimum numbers of guard channels and balance channel are determined under different traffic loads,which guarantees full use of the radio resource and seamless QoS at the same time.Finally, it concludes the dissertation briefly, and the future research work is indicated.