The Research Of Media Access Control Strategy And Packet Traffic Scheduling Algorithm In Wireless Mesh Networks

Wireless Mesh Network (Wireless Mesh Network: WMN) is a kind of distributedNetwork with Mesh topology structure, the communication between its nodes dependson their cooperation,WMN provide the user terminals with accessing to the Internetservice in Wireless relay way. Because wireless Mesh network has the advantages ofhigh rate, high capacity, low cost and so on, in recent years WMN has been concernedextensivly in the communication industry. Along with the promotion of the wirelessMesh network application, its service is also showing diversity trend, and differentservice to network’s quality of service (QoS) requirements are improved. Thecontradiction between the limited frequency resource and the needs of the businessgrowth increasingly sharply in Wireless Mesh network, so how to improve theutilization raito of wireless resource,realize resource fair accessing and satisfy the users’s quality of service (QoS) became the the key problems in current wireless Meshnetwork. And the media access control and packet scheduling mechanism are importantmeasures for guaranteing the network’s quality of service (QoS), this article with thenational863project "the hierarchical topology broadband wireless control Ad hocnetwork system research" demand for application background,the media access controland packet scheduling mechanism will be researched in the wireless Mesh network.The main function of media access control is to distribute or coordinatenetwork node visiting channel in a certain order and effective way.The purpose ofMedia access control is to realize fair access to the shared wireless channel resource,and on this basis to improve the system throughput and the utilization rate of thechannel. According to media access control protocol, this paper discussed byclassification, then do the key research on media access control of WiFi Mesh andWiMAX Mesh network respectively. For the media access control mechanism ofIEEE802.11s Mesh standard, in this article working principle of point coordinationfunction PCF, distributed coordinating function DCF and enhanced EDCA accessmechanism are analysed. In particular we adopt mathematical modeling analysis forEDCA access mechanism, Based on this mathematical modeling analysis,the influenceof backoff algorithm for throughput and service delay in system is discussed. In view ofthe defects of original EDCA mechanism, a improved backoff algorithm is proposed.For the media access control scheme of IEEE802.16Mesh standard, because its are based on the TDMA way, how to dynamic scheduled timeslot is key issues for mediaaccess control in IEEE802.16Mesh network. In this paper centralized and distributedtimeslot scheduling mechanism based on the TDMA way are analysed, in view of thecharacteristics of the two scheduling model and combining the QoS requirements,adiffer-service timeslot scheduling is proposed in the article.The purpose of the packet scheduling is maximize system throughput, at the sametime ensure different traffic’s quality of service to (QoS) and fairness between users. Inthis paper,the principle of a packet scheduling is analysied by using the queuing theoryand graph mathematical theory, also the packet scheduling processes and theperformance index of scheduling algorithm are introduced. The mature packetscheduling algorithm of cable network and wireless network are analysied in thearticle.Based on these theory a multi-stage fair group scheduling strategy isproposed,which combined with the services’s QoS requirements and characteristics ofwireless Mesh network.