| Wireless Mesh Network which evolved from a business application is a new type of broadband wireless network with high capacity, high-speed, strong robust, self-organized and so on. In Wireless Mesh Network, the key point of multi-channel MAC protocol is to locate and manage the limited channel resources; the research emphasis of routing protocol based on MAC attribution is to find out the optimal routing protocol between nodes, so as to enable the optimal throughput performance in the network connection. Thus, the users can get the most efficient end-to-end throughput performance.First, based on the recent research of the MAC protocols in Wireless Mesh Network around the world, we briefly introduce the system of the current MAC protocols, analyze and compare the performance of several typical multi-channel MAC protocols, then summarize the problems of multi-channel MAC protocols which need to be solved. Finally based on the research of the combination between the channel allocation and the routing protocol, two kinds of multi-channel routing protocols are introduced briefly.Based on all the research above, this paper proposes a kind of modified hybrid MAC protocol for multi-channel wireless Mesh network---MHMCP protocol which employing the hybrid channel allocation strategically. And this protocol builds the communication between the nodes by sorting the wireless interfaces and available channels, maintaining the information lists of neighbour nodes and building the system for the channel management and changeover. In order to get the good quality of all channels in the network, this protocol selects the reasonable fixed channel for all the network nodes according to the minimum channel interference rule. And in this paper we use the dynamic waiting time to solve the problem that the multi-channel terminal hidden, and to balance the relation between the data collision incidence and the interface utilization ratio. In addition, we dynamically adjust the time of data transmission according to the flow load of channels to make the dynamical distribution of the duration time of the allocation of channel, avoid the frequent interfaces changeover. Also to transmit more data on the channel and improve the channel utilization ratio. According to the influence of channel changeover delay and channel disturbance in the performance of the entire network under MHMCP, this paper proposes a new routing protocol--DSTP combining with MHMCP. This kind of routing protocol improves the network performance and the maximize network throughput.Finally, this paper analyzes the influence of the selection of the waiting time of the channels in the network performance, and we select the best waiting time by extensive simulations. We also simulate the network throughputs and average packet delay of MHMCP and other protocols under different transmission rates and multi-streaming concurrent. The simulation results show that the network throughput of the multi-channel MAC protocols is twice more than the single-channel MAC protocol. Especially, MHMCP has bigger throughput and smaller average packet delay. It is found out that the delay value caused by the channel changeover and the channel conflict increase when the network flow load is too big, and then gets a poor network performance become. In order to improve the performance, this paper adopts DSTP routing protocol which combines with MHMCP. The simulation of the network throughput of DSTP protocol and WCETT protocol shows that the adopted DSTP routing protocol has a better network performance. |
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