无线Mesh网络MAC协议与同步技术研究

发布时间：2019-06-16 16:07

【摘要】：无线Mesh网络(Wireless Mesh Network,WMN)是由无线自组织网络发展而来的一种新型网络,是目前无线网络研究的热点。MAC层的无线信道接入技术是无线Mesh网络的核心技术之一,MAC层信道接入时延和资源调度策略影响网络的整体性能。文章中MAC层信道接入采用TDMA接入方式,并对时隙分配和时间同步技术进行研究。本文利用各个节点对时隙需求不同动态地进行时隙分配来提高信道利用率和降低端到端时延;通过对时钟的漂移估计并进行补偿提高时间同步精度,具体工作如下:基于TDMA动态时隙分配算法在进行时隙分配时很少考虑到节点的实际负载,一般只考虑了节点自己需要发送的信息包数,没有考虑需要此节点转发的信息包数,导致时隙分配不合理。此外,节点分配的时隙顺序与节点号的顺序不一致导致信息传送中端到端延时急剧增加。因此本文提出改进算法TP-TDMA,利用预测机制来估计需要经过本节点转发的信息包数量,然后根据需要动态申请时隙个数,同时利用邻居节点的信息来优化优先级列表的权值设置,且对信息包进行优先级划分,降低端到端延时。仿真结果表明改进后的算法在不同跳数下、节点不同负载情况下的端到端延时都有一定的减少。本文主要研究了无线Mesh网络的分布式时间同步算法,在传统的同步算法中,节点只能在控制帧阶段接入网络,需要的时间较长,同时只是保证在同步时刻精度较高。所以本文提出了改进方法,使得节点在网络中任何阶段都能进行入网操作,大大减少了节点入网的时延。改进算法还在非周期同步期间对时钟漂移进行了估计,并对时间进行调整,获得了更高的同步精度。仿真结果显示改进后的算法节点入网时延缩短很多,同步算法的收敛速度更快,可以在达到同样的时间同步精度下可以延长同步周期,从而减少控制包的交互,降低能耗。
[Abstract]:Wireless Mesh Network (WMN) is a new type of network developed by wireless self-organizing network. MAC layer's wireless channel access technology is one of the core technologies of the wireless Mesh network, and the MAC layer channel access delay and resource scheduling policy affect the overall performance of the network. In this paper, the access mode of MAC layer in MAC layer is adopted, and the time slot allocation and time synchronization technology are studied. In this paper, the time slot allocation is used to improve the channel utilization rate and reduce the end-to-end time delay. A TDMA dynamic time slot allocation algorithm seldom takes into account the actual load of the node in the time slot allocation, and generally only considers the number of information packets that the node needs to send, and does not consider the number of packets required to be forwarded by the node, resulting in an unreasonable allocation of the time slot. In addition, the sequence of time slots allocated by the nodes does not accord with the order of the node numbers, resulting in a sharp increase in the end-to-end delay of the information transmission. therefore, the improved algorithm TP-TDMA is proposed, the number of the information packets to be forwarded by the node is estimated by the prediction mechanism, the number of the time slots is dynamically applied according to the requirement, the weight setting of the priority list is optimized by using the information of the neighbor nodes, and the information packets are prioritized, And the end-to-end delay is reduced. The simulation results show that the improved algorithm has a certain reduction in the end-to-end delay of the node under different load conditions. In this paper, the distributed time synchronization algorithm of the wireless mesh network is mainly studied. In the traditional synchronization algorithm, the nodes can only access the network in the control frame stage, and the time required is long, and the accuracy of the synchronization is only guaranteed. The improved method is proposed in this paper, so that the network access operation can be carried out at any stage in the network, and the time delay of network entry is greatly reduced. The improved algorithm also estimates the clock drift during the non-periodic synchronization and adjusts the time to obtain higher synchronization accuracy. The simulation results show that the time delay of the improved algorithm node is much shorter, the convergence rate of the synchronization algorithm is faster, and the synchronization period can be extended under the same time synchronization accuracy, thereby reducing the interaction of the control packet and reducing the energy consumption.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.5

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