| With the people's rapid demand for voice,video,data,Backbone network has considerable size. The"last mile"access between users and backbone network becomes the focus of the current study. A new Broadband Wireless Metropolitan Area Network protocol named IEEE 802.16 is proposed, which provides a unified global standard for Broad Wireless Access. Although IEEE 802.16 protocol's MAC Layer defines the QoS signaling mechanism,service types and corresponding bandwidth request/allocation mechanism and so on . However, some mechanisms'specific design details in IEEE 802.16 are left to the developers to realize, such as admission control mechanism,packet scheduling algorithm, etc.Based on a detailed technical analysis for IEEE 802.16 MAC layer, in view of the deficiencies existing in the IEEE 802.16's QoS framework and the relevant literatures'QoS framework, this thesis improved a QoS framework. In the framework we describe the function modules on BS and SS, propose the realized methods for some related modules, and summarize the process of data transmission between BS and SS.Subsequently we propose an admission control mechanism combined with dynamic bandwidth allocation based on IEEE 802.16.The proposed admission control mechanism considers the support for both fixed users and mobile users, and adopts the method of dynamic bandwidth allocation and bandwidth borrowing. The mechanism's target is to ensure fairness in the provision of services for fixed and mobile users, and at the same time to improve the system bandwidth utilization. Finally, we test our admission control mechanism's performance through simulation. |
