Research On Radio Resource Allocation For IEEE802.16 Systems

As the society develops and communication technology advances, the wireless access networks have demonstrated a trend toward higher capacity and more diversified service qualities. To coupe with this trend technology advance has to be achieved in several layers. In the PHY layer OFDM (Orthogonal Frequency Division Multiplexing) is becoming more popular for its strength at dealing with multi-path fading channels. And in the MAC layer more sophisticated radio resource management is required to promote the system's utilization efficiency and to diminish the gap between limited radio resources and increasing service requirements. This thesis focus on the optimized radio resource allocation for multi-media services with different QoS requirements with OFDMA signaling, based upon the IEEE802.16 WMAN standards.The thesis researched on the packet scheduling issues in wireless systems, and illustrated the multi-dimensional performance on bandwidth efficiency and users' service fairness. And those conventional scheduling methods cannot be readily used in IEEE802.16. Based on the features of IEEE802.16 OFDMA mode the thesis proposed a proportional fairness scheduling method for BE services. And adopting the OFDMA mode's time-frequency dimensional frame structure the burst mapping method will greatly determine the system's signaling overhead and transmission power stability. By mapping with two-dimensional concerns the thesis proposed fragment-optimized and transmission power stability optimized mapping methods.The IEEE802.16 is no longer limited to single service with constant rate; in fact the service can adjust its own QoS parameters. The standard categorizes all the services into four types, and according to the transmission delay requirement they can further be categorized into two classes: real-time and non-realtime. Based on the essence of exchangeability between power and bandwidth, the thesis proposed a power-bandwidth joint allocation method. It can maximize the overall non-realtime throughputs while guaranteeing the real-time throughput requirements.In real deployment the co-channel interference is severe in multi-cell wireless systems. The co-channel interference can be mitigated by frequency reuse. And more sophisticated system planning will adopt several frequency reuse scenarios simultaneously. The thesis proposed a dynamic frequency reuse based sub-channel allocation method that achieves better fairness than the single frequency reuse systems.