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The wireless mesh network is an emerging wireless network technologies, it is produced in the Ad hoc network, Ad hoc network is generated in order to adapt to the needs of the war, to enhance the robustness of the wireless sensor network, with the end of the war, Ad hoc network has been widely used in the field of civil and commercial development of Ad hoc networks there are two trends, one is to continue along the traditional service development, and the other in the direction of the military turned to the direction of the service in civil and commercial Now the wireless mesh network. Unlike traditional wireless network technology, the wireless mesh network information is not limited to \different, so unique advantages of wireless mesh network group, robustness, self-healing, so it can be applied in hard to reach areas of the wired network, or post-disaster communications occasions. With the increase of wireless mesh network applications, some applications, such as voice, image transmission delay, bandwidth and other QoS (Quality of Service, Quality of Service) parameters sensitive to traditional routing protocols based on hop count metrics , in the path of the sending node to the destination node, the path of least hops, link status (delay, bandwidth, etc.) is not necessarily good, therefore, the need to research and development of new routing protocols or improve existing road agreement it QoS parameters can be obtained to meet the QoS parameters of the routes, and can be obtained in the route discovery. This article provides insight wireless mesh generation, characteristics, structure, wireless mesh three structures: infrastructure mesh structure, the mesh structure of the client, a mixed mesh network structure, hybrid mesh network structure is the most application value . This article studies the wireless the typical mesh routing protocol DSDV routing protocols AODV routing protocol, the working mechanism of the DSR routing protocol, and construct three simulation experiments, the first experiment and the second experiment constructed a 200 environment of the wireless node, the previous experiment node is stationary, after an experiment node to stay at a position 50S, other conditions are the same, the simulation time 100s, using cbr stream, the maximum number of connections to 20, DPS Submit 15 packets, ranging from 300 × 300, comparative analysis not only on the various indicators of the three protocols in a given environment, but also to test the impact of node mobility on the effect of the agreement; construct a 100 in the third experiment nodes in the wireless environment, change the node number of packets sent per second, sending 20 packets per second to send 200 packets per second, average delay of these three agreements endpoint to endpoint packet successfully received rate were analyzed. . The routing criteria is to select the path of the routing protocol standards, In this paper, the number of hops, single hop roundtrip time, per-hop packet on the delay, it is desirable that the number of transmissions, the desired transmission time routing criterion single routing criterion effect not ideal, should seek the routing criteria based on comprehensive criteria. Tools and files necessary to build a simulation environment. The NS2 simulation tools works, command, awk language, the trace file format, gnuplot drawing tools, measuring the performance of wireless network script. QoS concepts and three typical depth study QoS guarantee model, illustrate the steps to add new routing protocol parsing AODV source AODV is improved on the basis of: (1) congestion avoidance AODV routing protocol hop count metric based congestion control, therefore, may appear, sometimes the network traffic is not great, but after a certain node is too much traffic, leading to packet delay of the node increases, a further increase in traffic , will have a loss. In order to solve this problem, the protocol improved, first to introduce a concept node load, node load is defined as the length of the packet is queued in the queue the ratio of share of the total queue length. Timing node load for testing, if the node load exceeds 80%, this value can be adjusted according to the actual network traffic, the route discovery should \evenly distribute traffic may walk the path from the number of hops is not optimal, but it can avoid congestion, reduce delays, and overhead is not great. (2) The delay control, some applications, for example, voice services is more sensitive to the delay of the data stream, because some, to the packet transfer delay control, that is, the packet routing selection to meet the delay requirements. The source node sends a routing request, the delay request to be added to such a route request is received, the network node, to calculate the packet experiencing the delay, if forwarding is not satisfied is discarded. (3) bandwidth control AODV protocol only choose to jump the shortest route, but this path does not guarantee packet bandwidth requirements, so when a node receives a certain mechanism should be used for bandwidth-sensitive packet computing to each neighbor node bandwidth, select the path meet the bandwidth request. Through these improvements, the formation of a congestion control, delay control, bandwidth control, QoS routing protocol. Hello packets, rreq packet, rrep packet format was expanded, improved process flow rreq packet, rrep packets.
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