The Research Of IEEE 802.16 Standards And The Design And Implementation Of Call Admission Control

The PHY layer and the MAC layer specification are defined in IEEE 802.16 standard. In the PHY layer, OFDM/OFDMA techniques are introduced to guarantee the reliable data transmission in various physical environments. In the MAC layer, service flows are classified into the UGS, rtPS, nrtPS, BE and ertPS (defined in IEEE 802.16e) types, and the QoS requirements are satisfied perfectly by the MAC layer mechanisms respectively. However, the radio resource management algorithms used to implement the QoS support are not given by the standard. So, all the issues about radio resource management are left for researchers to implement.First, this paper introduced IEEE 802.16 protocol and WiMAX forum, and researched the key techniques in WiMAX system in detail according to the comparison with McWiLL system. Second, based on the introduction to the work process of the radio resource management, this paper discussed a packet scheduling algorithm called 'Maximum Deviation Channel First' (MDCF) in WiMAX system. Above all, this paper emphasized the design of a revenue-aware dynamic call admission control algorithm in WiMAX system considering the weakness of the MDCF algorithm.The innovation of this paper is that the proposed algorithm aiming at IEEE 802.16 OFDMA systems takes the revenue of the service providers' into consideration and adjusts the threshold of the reserved guard channel dynamically. First, the revenue generated by accepting a connection was introduced into the admission priority function to produce high revenue of the system. Second, the proposed algorithm adjusted the reserved channel according to the state of system dynamically so as to reduce the call dropping probability (CDP) and the call blocking probability (CBP) simultaneously. The simulation results compared with the traditional algorithms show that the proposed algorithm can decrease CDP and CBP effectively to achieve high users' satisfaction degree, while increase the revenue of the network at the same time.