Performance Analysis And Resource Scheduling Scheme For IEEE802.16-based Wireless Mesh Networks

Wireless mesh networks are currently emerging as an efficient and promising solution for low-cost broadband Internet access. Wireless mesh networks are characterized by dynamic self-organization, self-configuration and self-healing to enable quick deployment, easy maintenance, low cost, high scalability and reliable services. Time Division Multiple Access-based (TDMA-based) wireless mesh networks and Carrier Sensing Multiple Access/Collision Avoidance-based (CSMA/CA-based) wireless mesh networks differ significantly in Medium Access Control (MAC) layer technology, topology awareness, information exchange and distributed scheduling scheme, so they cannot use same technologies. This thesis studies some theoretical and technical problems in performance analysis and resource schedule.In traditional performance analysis for wireless mesh networks, the ratio of control slots number to total slots number and coexisting of relay traffic and forwarding traffic are not considered. The relation between the collision probability and the ratio of control slots number to total slots number is derived. Further derivation leads to the relationship between the available capacity and node density, transmission rate, transmission range, hop counts, and the ratio of control slots number to total slots number. Simulation results show the optimal ratio of control slots number to total slots number. Moreover, the transmission range that achieves100%connectivity probability is formulated.The transmission scheduling scheme specified in the mesh mode of IEEE802.16protocol has two disadvantages, low control slots utilization ratio and high three-way handshake delay. A transmission scheduling scheme, randomized self-learning transmission scheduling scheme is proposed for IEEE802.16-based wireless mesh networks to overcome these two weaknesses. Meanwhile, because the IEEE802.16protocol lacks link scheduling scheme and TDMA-based wireless mesh networks should support real-time traffic transmission, a heuristic distributed end-to-end link scheduling scheme is presented. The scheme utilizes hop-aware route discovery and sequential slots reservation scheme to reduce the end-to-end delay for delay sensitive traffic. The end-to-end delay carried out by the scheme is formulated.The mesh mode of IEEE802.16protocol does not have the specification for handoff management scheme, and IEEE802.16-based backbone wireless mesh networks are expected to support various types of applications with diverse priorities. A pre-handoff cooperation scheme is proposed to increase the transmission reliability of roaming mesh client by the cooperation between the associated mesh router and the new routers. In addition, a QoS-aware mesh router selection scheme is presented to decrease the total blocking traffic by considering the RSSI (Receive Signal Strength Indicator), traffic priority and bandwidth requirements together.