Research On MAC Protocol And Synchronization Technology In Wireless Mesh Network

Wireless Mesh Network(WMN)is a new type of network developed by wireless self-organizing network,which is the hotspot of future wireless network research.The overall performance of the wireless Mesh network is determined by the wireless channel access technology at the MAC layer.In this thesis,TDMA access is adopted in MAC layer channel access,and slot allocation and time synchronization are studied.The nodes are used to dynamically improve the channel synchronization and reduce the end-to-end delay in the thesis.The time synchronization accuracy is improved by estimating and compensating the clock drift.The specific work is as follows:Currently,the existing TDMA slot allocation algorithm rarely takes into account the actual load of the node in the time slot allocation.Generally,only the number of packets that the node needs to send is taken into account,and the number of packets that need to be forwarded by this node is not considered,unequal allocation of time slots,resulting in network congestion.In addition,the order in which the timeslots assigned by the nodes do not coincide with the order of the section numbers results in a sharp increase in endto-end delay in the message transmission.Therefore,this thesis proposes an improved algorithm TP-TDMA,which uses the prediction mechanism to estimate the number of packets that need to be forwarded through the node.Then,dynamically apply the number of slots according to the needs and use the information of the neighbor nodes to optimize the weight list of the priority list.And prioritize packets to reduce end-to-end latency.The simulation results show that the improved algorithm has a certain decrease in end-to-end delay under different load conditions.This thesis mainly studies the distributed time synchronization algorithm of wireless Mesh network.In the traditional synchronization algorithm,nodes can only access the network in the control frame stage,taking a long time,and only guarantee the same precision at the synchronization time.Therefore,the author puts forward the improvement method,which makes the node can carry on the network operation at any stage in the network,greatly reducing the delay of the node network.The improved algorithm also estimates the clock drift during nonperiodic synchronization and adjusts the time to achieve higher synchronization accuracy.The simulation results show that the improved algorithm nodes are much shorter and the convergence speed of the algorithm is faster,and the synchronization period can be prolonged by the same time synchronization precision,thus reducing the interaction of the control packets and reducing the energy consumption.