The Design of QoS Provisioning Mechanisms for Mobile WiMAX Networks

QoS (Quality of Service) provision imposes a very challenging task for WiMAX networks. IEEE 802.16 standard has mentioned the use of QoS mechanism without the detailed implementation specification. In this paper, we combine call admission control, bandwidth allocation and packet scheduling to design the QoS mechanisms in WiMAX system. We evaluate the performance of V2oIP (Voice & Video over IP) applications under the fixed and mobile WiMAX environment. It is noted that in the mobile environment, variable modulation rate affects transmission performance significantly and often causes substantial degradation of transmission quality. We thus propose adaptive codec and adjustable bandwidth requirement mechanism to decrease connection blocking probability and packet dropping probability. Performance results have demonstrated the effectiveness of the proposed scheme in enhancing the system performances.