Research On Key Technologies Of Routing Protocol For Wireless Mesh Networks

WMN(Wireless Mesh Networks) have attracted lots of attention in recent years. WMN is a new kind of wireless multi-hop network architechture. By inheriting the advantages of both WLAN and MANET, WMN can be deployed in mesh topology and provide stable and fast end-to-end wireless transmission. The appearance of WMN establish a very solid foundation for commercial"last mile"wireless broad band accessing.Routing protocol is one of the key technologies of WMN. However, many existing routing protocols for WMN can not fully meet the actual demands of practical applications entirely. Therefore, it is nessesary to design new routing protocol based on the architechure characteristics of WMN in order to improve the performance of WMN.In this dissertation, the background and basic concepts of WMN are introduced firstly, a outline of those important research fields, related project, standard and commercial productions is given. Hence, the goal and guildline of this dissertation are proposed. A comprehensive and detailed survey on research of routing protocol for WMN is given subsequently in Chapter 2. Based on the above discussion, in this dissertation, two different routing protocols are designed respectively in order to match the corresponding scenarios of backbone WMN and hybrid WMN. This is also the main task and innovation of this dissertation.Backbone WMNTherotical analytical model and polynomial time algorithm for path capacity problem: It has been proved that the computation of path capacity is NP-hard in multi-channel multi-radio wireless networks. Thereby, a path capacity analytical model is proposed in Chapter 3, which convert path capacity problem into a constrained optimization problem. A corresponding polynomial time complexity heuristic algorithm PCEAGS is also implemented by the introduction of greedy strategy. The simulation result shows that it can estimate path capacity accurately without bring in extra network load.End-to-end high throughput routing protocol: In order to achieve end-to-end high throughput routing protocol, on the basis of sum up the shortages of existing routing metric, a new routing metric called residul path capacity is proposed based on research in Chapter 3. By summarizing different types of channel occurring, a calculating formula of residul path capacity is given. Hence, the protocol EHTR is designed by aimed at maximizing end-to-end throughput, and the mechanisms of routing discover and routing failure repair are also discussed in particular. Simulation result shows that protocol EHTR can improve end-to-end throughput prominently. Hybrid WMNDynamic channel assignment strategy based on local topology: With the advantages of multi-channel and multi-radio, WMN can provide high end-to-end throughput, but also introduce the complicated channel assignment problem. It is known that channel assignment in multi-channel multi-radio wireless networks is NP-Hard. So algorithm LICA is proposed in Chapter 5. By using local topology and the channel usage status of all the neighbor nodes, it can reassign channel adptively with the guild of heuristic constrains. Experiment result shows that algorithm LICA has not only lower time complexity and better expansibility, but also ability of load-balance.Traffic-aware load-balance routing protocol: Due to the wireless channel's physical characater of broadcasting, congestion will occur oftenly in WMN, which could result in frequent channel collision and decline of network performance. In order to solve this problem, based on the work of channel assignment in Chapter 5, protocol TLR is proposed. TLR is a cross-layer routing protocol by integrate traffic detecting, congestion control and end-to-end fairness transmission. Simulation result shows that protocol TLR can balance the traffic loads over WMN, guarantee end-to-end fairness transmission, and also with well expansibility.This dissertation studies comprehensively and thoroughly the key technologies of designing WMN routing protocols and gives effective routing proposals in terms of different problem. Nevertheless, more challenging problems exist in the field of WMN routing design, such as security routing protocol, multi-path routing protocol and QoS routing protocol, etc.