The Research Of Scheduling Algorithm Of Bandwidth Allocation For WiMAX MAC Layer

The technology of WiMAX, which is based on IEEE802.16 standards, has become a research hotspot in the field of communication for its high transmit rate,services of heterogeneous classes of traffic and effective network mode. As a competitive technology of wireless network, WiMAX provide the QoS(Quality of Service)guarantees to different applications. However, bandwidth scheduling in MAC layer,which makes all kinds of traffic have satisfied services through bandwidth allocation,is one of the important parts in implementing QoS guarantees. Although the connection-oriented transmit mechanism and complete service management for MAC layer are provided by the standard, the scheduling algorithms which implement the QoS support are not given, so it's a meaningful topic to discuss the MAC bandwidth scheduling.This essay will firstly introduce the development of various kinds of wireless access technology, while those respective features will be analyzed and the trend of development will be also compared. Afterwards there will be a summary about the technical characteristic and network application of WiMAX, and the MAC protocol of IEEE802.16 especially it's QoS mechanism will be elaborated at the same time. Next, various generic scheduling algorithms which are used in wired and wireless network will be discussed. Based on the analysis and improvement of the scheduling algorithm of different services, the Classified Compensated Bandwidth Scheduling (CCBS) architecture for WiMAX MAC layer is proposed, which uses two layer scheduling architecture, the first layer is half-priority scheduler based on reserved and the second layer have four scheduler point to different service. Furthermore, this architecture combined with compensation mechanism, can provide long term fairness for service flow scheduling. The NS2 simulation results show that the proposed architecture can meet the QoS requirement and fairness for types of trcffic.