| The kernel function of Wireless Mesh Networks(WMNs) is the routing ability. However, it is very difficult to perform routing in WMNs for the instability, unreliability, high BER, and interference-sensitivity of wireless transmission. Design of routing in WMNs emphasize on static scenario, high capacity and high reliability, which is very different from Wireless Ad Hoc networks. As a result, some new challenges appear when it comes to research of routing in WMNs. In recent years, many novel ideas and technologies of routing have been proposed, such as opportunistic routing(OR) and multi-path routing, followed with some compatibility and optimization issues.A series of key technologies of opportunistic routing and multi-path routing for wireless mesh networks are investigated in depth, including forwarding model, metric design, multi-rate control of OR, and proactive multi-path routing. The main innovative works of the dissertation can be summarized as follows:Firstly, a throughput efficiency based OR mechanism is proposed in order to overcome the problem that the metrics used by current OR protocols can not reflect the throughput capacity directly and restrict the number of forwarders effectively. An analysis model of OR is designed and a metric named Expected Anypath Throughput(EAT) based on the model is proposed. The saction of EAT on forwarders is proved theoretically. The traditional ACK reply mechanism is improved, as a result the PRR of ACK is heightened and retransmissions caused by invalid ACK are reduced. A forwarder selection and prioritizing algorithm is proposed by dynamic programming. Simulation results show that the throughput gain of proposed algorithm is up to 48.91% over ETX and 11.04% over EN.Secondly, two Multi-rate OR algorithm are proposed:an end-to-end delay based Multi-rate OR algorithm and an minimum packet loss based Multi-rate OR algorithm. In the first one, a novel multi-rate routing metric (EEED) is designed by introducing opportunistic forwarding time and a forwarder selection mechanism (STMOR) is designed which can select optimal transmission rate and get a forwarder list with minimum delay. The second one aims at reducing Loss rate, and a multi-rate metric ETR (Effective Transmission Rate) is proposed associated with the propability of successful transmission. The author proves the priority rule of forwarders based on ETR, and designs a forwarders selection algorithm which can obtain a forwarder list with maximum ETR. STMOR emphasizes on heighten forwarding efficiency by optimizing delay, while MLA prefers to reduce loss rate and avoid duplicate transmission. Extensive simulations show that the proposed multi-rate OR's can achieve better performance compared to others..thirdly, a geographic OR in WMNs is proposed. Metrics using by traditional geographic OR only consider link quality between source and forwarders without considering links between forwarders and destination. In order to solve this question, a concept named Packet Successful Advancement(PSA) is proposed which introduces link quality between forwarders and destination. A further balance policy (PAE) is proposed after analysing the characteristics of PSA, which makes a tradeoff between packet advancement and forwarding time. Simulation results show that the proposed geographic OR performs better and the analysis of PSA and PAE are proved.Finally, a multi-path routing algorithm based on diffusing update algorithm(DUAL) is proposed for the first time. A improvement on traditional DUAL is accomplished, which greatly depress the number of diffusing. And at the same time routing is kept loop free. Then, a proactive multi-path routing based on modified DUAL is proposed and the routing steps including neighbor discovery, route discovery and maintain are particularly expounded. Simulation results show that the proposed multi-path routing can achieve a performance almost equal to current multi-path routing and much better than single-path routing.
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