Research Of Node Cooperation And Distributed Scheduling In 802.16 Mesh Networks

With the fast development of wireless communication, wireless access technology has witnessed a trend of broadband communication and all-IP network architecture. As a new broadband wireless access technology after Wireless LAN, IEEE 802.16, which bases its core network on all-IP architecture, provides broadband wireless connection for fixed, nomadic and mobile equipment. It supports PMP (Point-to-Multipoint) and Mesh networks, in which the mesh network combines the advantages of both cellular and ad hoc networks. But there are issues that need to be resolved for the 802.16 mesh network. On one hand, node cooperation is one of the most important features of mesh network, but there is a lack of research on how nodes should cooperate, and how some specific cooperation strategies influence network performance. On the other hand, although the standard has defined network schedule control messages, the specific scheduling mechanism is open for research.This thesis focuses on the node cooperation and distributed scheduling mechanism in 802.16 mesh network. First, we apply cooperative game theory to establish the node cooperation model, then by using the cooperation dependency graph, we provide the condition of Nash equilibrium for Tit-for-Tat (TFT) cooperation strategy, and prove the general existence of the equilibrium condition. Afterwards, we carry out research on what impact the holdoff exponent has on node throughput and three-way-handshaking time, and propose a dynamic holdoff exponent mechanism. The mechanism is based on the given cooperation strategy and classification of the node activity. Simulation results show that, TFT strategy can improve network throughput, and that dynamic holdoff exponent has a positive control on node competition, thus is more scalable compared to the static holdoff exponent mechanism.This thesis also applies repeated game theory to analyze node cooperation in mobile mesh network, and give the condition of Nash Equilibrium existence. By simulation, the stability of Nash Equilibrium under different node density and cooperation cost is verified, which sheds some light on the application of future mobile 802.16 mesh network.