Research On QoS Mechanisms Of IEEE 802.16 MAC Layer

In the area of communication, as wireless communication plays a more and more important role in our common life, BWA (Broadband Wireless Access) technology which is an important part of it is under serious consideration for its wide prospect and unevaluated potential. IEEE 802.16 is a kind of BWA technology used in WMAN (Wireless Metropolitan Area Networks). It can provide flexible BWA with wider area, higher rate and mobility supporting, which makes the 802.16 standard having a very wide application space and become a research hotspot.The MAC layer of IEEE 802.16 is connection oriented, and many kinds of multimedia services are supported by it. Since various services correspond with different quality of service (QoS) parameters, to meet the QoS requirements of various services, IEEE 802.16 standard has defined the QoS interface mechanism but not the practical implementation method. For the sake of increasing frequency efficiency of the system, satisfying fairness among users and supporting different QoS requirement for various services, research of the scheduling architecture and scheduling algorithm of MAC layer which is the core part of QoS mechanism makes great sense.In this thesis, scheduling architecture and scheduling algorithm of MAC layer was deeply researched based on the QoS architecture of IEEE 802.16. A new scheduling architecture based on hierarchical layered design idea was proposed for MAC layer. The hierarchical layered design idea is reflected in the following three aspects: 1) schedule separately in base station (BS) and subscriber station (SS); 2) split the whole scheduler into packet scheduler and radio resource allocator; 3) a two-tier scheduling algorithm is used in the packet scheduler, in which the first tier schedules among various service types and the second tier schedules among different queues belong to the same service type. Based on this new scheduling architecture, a packet scheduling algorithm was proposed for the 802.16 BS system, which considers about fairness and efficiency and could adjust uplink and downlink bandwidth dynamically. The simulation results showed that higher throughput can be achieved using dynamic bandwidth allocation method when unbalanced traffic is heavy and the scheduling algorithm can provide good fairness.