Research On Channel Assignment And Routing Algorithm In Multichannel Wireless Mesh Networks

Wireless Mesh Networks (WMN) consists of wireless mesh routers and terminal equipments via multi-hop, it possesses a high transmission speed, a wide coverage and flexibility of network formation and low cost. WMN is one of relatively competitive solutions to solve the "last mile" problem. WMN can be divided into terminal mesh networks, infrastructure mesh networks, and hybrid mesh networks according to the topology of network and the function of node. For infrastructure mesh networks, the throughput in network will determine the number of terminals which can access network. The IEEE 802.11 standards define a number of orthogonal channels, while the development of physical technology makes wireless device with multiple interfaces possible. To study how to effectively use multiple orthogonal channels and multiple interfaces to increase the throughput of wireless mesh networks and decrease the radio link transmission interference is of great significance. In this thesis, the study on infrastructure mesh networks is done based on IEEE 802.1l standards to use multiple orthogonal channels to improve the network throughput.The characteristics of WMN are studied firstly. The analysis shows that the infrastructure mesh networks are primarily as a data backhaul network of terminal nodes. Most traffic in infrastructure mesh networks is the traffic of terminal nodes to or from gateway; and some traffic is between nodes within wireless mesh networks. According to the characteristics of traffic in infrastructure mesh networks, the interfaces in mesh router node are classified to two kinds. One is Data Backhaul Interface (BI) which is responsible for the transmission of traffic to or from gateway; the other is Internal Traffic Transfer Interface (TI) which is responsible for data transmission and data forwarding between terminal nodes. The constraints which the channel assignment should satisfy are analyzed. The criteria which channel assignment should follow is proposed. The Channel assignment based on group management is proposed according to the size of channel interference cost in the region of channel interference. According to the proposed channel assignment strategy, the backhaul interface can be allocated channel with the interference cost in the channel region as small as possible, thus reducing the channel collision, reducing channel interference and improving network throughput. Simulation results show that the proposed algorithm can reduce regional interference, and can fully utilize channel diversity and get higher network throughput.Secondly, the routing protocols of WMN are studied owing to find that the routing protocols based on traditional self-organizing network are mostly working in the situation of single interface and single channel. AODV-MRMC routing protocol based on multi-interface and multi-channel extended is proposed for the shortage of the standard AODV, to increase the network throughput by taking full advantage of multiple orthogonal channels. Finally, many simulation experiments in the OPNET are done about AODV-MRMC. AODV-MRMC and AODV are compared on the performance. Experimental result shows that AODV-MRMC are better than AODV on the network throughput, decreasing media access delay, and keeping higher packet delivery rate.