Research And Implementation Of Scheduling Algorithm On MAC Layer In IEEE 802.16 Wireless Mesh Network

Wireless Mesh network has attracted the attention of industry due to its features such as flexibility to expand, self-configuring, self-healing, wide coverage and so on. Since the multi-hop wireless transmission environment is very complex, there will be serious link interference and data conflicts. Therefore, how to design the appropriate scheduling algorithm to improve the performance of the wireless Mesh network is a research focus. In addition, with the acceleration of information technology, multimedia services and applications have become more and more popular and how to ensure the quality of service is one of the difficulties. This paper analyzes the TDMA-based wireless Mesh network MAC layer protocols, and focused on scheduling algorithm design and implementation of the MAC layer to provide QoS. The main achievements are listed as following:According to the architecture and features of wireless Mesh network, this thesis analyzes the IEEE 802.16e MAC layer protocol of Mesh mode, including:the process of network initialization, scheduling type of service algorithm, sub-packing mechanisms and MAC management messages. This is a foundation for follow-up implementation. This thesis has improved the protocol for QoS gurantee. A Priority Coordinated Distributed Scheduling with Reserved Timeslot (PCDS-RT) is given. The simulation proves that three-way shakehand procedure can be accelerated by this algorithm. To gurantee QoS when decreasing signalling overhead to improve channel utilization, the initial allocation of wireless resource uses IntServ strategy while uses Diffserv sheme for the second scheduling to meet the need of the different QoS demand of multiple service flow. NS2 simulation demonstrates that this alogrithm can gurantee QoS demand and achieve high throughput. This algorithm is also simple and effective which is easy to be upgraded and improved in the real system.A scheduling module of Mesh MAC protocol stack software is designed based on the work above in this paper. This module can accomplish the scheduling function in mesh MAC protocol stack and also can be used as a platform of certification of scheduling data. There are some advantages as below:easy to be transplanted to different physical layer; easy to be upgraded for internal algorithm; proper definition of each interface of other module and lower coupling degree. This module can be run stably on mesh-MAC software and provide high QoS guarantee and high channel utilization.