Research On Radio Resource Management In Broadband Wireless Access Networks

Nowadays, IEEE 802.16 is one of the most respective technologies in the broadband wireless access (BWA) area. One target of BWA is to fully support the multimedia service, which is becoming a dominant service. In order to support this kind of service, admission control, packet scheduling, dynamic subcarrier allocation and power control are introduced in IEEE 802.16 to ensure the quality of service (QoS).Since the admission control is the highest level of the resource management and the first step to ensure the QoS, the mechanism of admission control will impact on the lower layer resource management mechanism and the algorithm selection of resource allocation and scheduling. So, in this thesis, admission control mechanism is analyzed. Considering the potential QoS degradation resulting from the traffic variability, a limitation is set to the overflow probability which is the probability that the required bandwidth is greater than the available bandwidth. Also, the overflow probability is considered as admission control criterion. According to the IEEE 802.16 standard, classic traffic model was used to model the system and to derive the admission control algorithm. Besides, Markov chain theory was used to analyze the performance and theoretical performance results were given. Finally, the enhanced IEEE 802.16 module in network simulator 2 was used to simulate the CAC algorithm and evaluate the performance. The results show that the admission control could prevent the QoS degradation resulting from the traffic overflow and the resource utilization is comparable with other admission control mechanism when the best-effort traffic exists in the system.Although IEEE 802.16 technology aims at providing high bandwidth required service such as multimedia service, the voice service also should be supported well since it is the basic service. With the trend of all-IP, the VoIP will replace the circuit-voice.Considering this, in the second part of this thesis, the VoIP performance in TDD-OFDMA based IEEE 802.16 networks was investigated. A two-state Markov Modulated Possion Process was used to model the aggregated VoIP traffic. Based on the traffic model, a VoIP performance analysis model was proposed. Also, the impact of MAC layer mechanism such as resource allocation, scheduling and packet aggregation on the VoIP performance was analyzed. From the simulation results and the numerical results, the suitable chosen of MAC layer parameter could improve the VoIP performance significantly and the MAC layer packet aggregation could not only decreases the packet head overhead and signaling overhead but also improves the VoIP performance and increases the VoIP capacity.