QoS Research Based On 802.16 Protocol

802.16 protocol is a wireless broadband protocol for the purpose of "Last a Mile" access with higher speed and broader applications. To meet theneeds of multimedia applications , 802.16 standards define four different services types and corresponding priorities and make a detailed instructions on the management of QoS service flows. But in the protocol there are some undefined important problems including packet scheduling , admission control and flow moniter.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 , 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.Admission control is very important to mantain QoS. Its task is to determine the entrance of a new service. The thesis proposes an admission control algorithm based on the dynamic threshold. The algorithm sets different thresholds for different priority service request and the threshold can adjust according to the varitations of the system load. The algorithm can ajust the reservd resource for the realtime traffic according to the not-realtime traffic packet loss to maintian fairness. From the results of simulation, the algorithm can embody the priorities of different traffic, self-adaption and fairness.In the Broadband Wreless Acess network, MAC layer packet scheduler is one of the main elements in the QoS architecture. It can classify different packets from differnent users and allocate network resource to improve the utility of the network. The thesis proposes a packet scheduling algorithm based on 802.16 service types .The algorithm combines srevice division and inspection of the channel state. It can also compensate the lagged nrtPS service type.