【摘要】：無(wú)線(xiàn)Mesh網(wǎng)絡(luò)(Wireless Mesh Network,WMN)是由無(wú)線(xiàn)自組織網(wǎng)絡(luò)發(fā)展而來(lái)的一種新型網(wǎng)絡(luò),是目前無(wú)線(xiàn)網(wǎng)絡(luò)研究的熱點(diǎn)。MAC層的無(wú)線(xiàn)信道接入技術(shù)是無(wú)線(xiàn)Mesh網(wǎng)絡(luò)的核心技術(shù)之一,MAC層信道接入時(shí)延和資源調(diào)度策略影響網(wǎng)絡(luò)的整體性能。文章中MAC層信道接入采用TDMA接入方式,并對(duì)時(shí)隙分配和時(shí)間同步技術(shù)進(jìn)行研究。本文利用各個(gè)節(jié)點(diǎn)對(duì)時(shí)隙需求不同動(dòng)態(tài)地進(jìn)行時(shí)隙分配來(lái)提高信道利用率和降低端到端時(shí)延;通過(guò)對(duì)時(shí)鐘的漂移估計(jì)并進(jìn)行補(bǔ)償提高時(shí)間同步精度,具體工作如下:基于TDMA動(dòng)態(tài)時(shí)隙分配算法在進(jìn)行時(shí)隙分配時(shí)很少考慮到節(jié)點(diǎn)的實(shí)際負(fù)載,一般只考慮了節(jié)點(diǎn)自己需要發(fā)送的信息包數(shù),沒(méi)有考慮需要此節(jié)點(diǎn)轉(zhuǎn)發(fā)的信息包數(shù),導(dǎo)致時(shí)隙分配不合理。此外,節(jié)點(diǎn)分配的時(shí)隙順序與節(jié)點(diǎn)號(hào)的順序不一致導(dǎo)致信息傳送中端到端延時(shí)急劇增加。因此本文提出改進(jìn)算法TP-TDMA,利用預(yù)測(cè)機(jī)制來(lái)估計(jì)需要經(jīng)過(guò)本節(jié)點(diǎn)轉(zhuǎn)發(fā)的信息包數(shù)量,然后根據(jù)需要?jiǎng)討B(tài)申請(qǐng)時(shí)隙個(gè)數(shù),同時(shí)利用鄰居節(jié)點(diǎn)的信息來(lái)優(yōu)化優(yōu)先級(jí)列表的權(quán)值設(shè)置,且對(duì)信息包進(jìn)行優(yōu)先級(jí)劃分,降低端到端延時(shí)。仿真結(jié)果表明改進(jìn)后的算法在不同跳數(shù)下、節(jié)點(diǎn)不同負(fù)載情況下的端到端延時(shí)都有一定的減少。本文主要研究了無(wú)線(xiàn)Mesh網(wǎng)絡(luò)的分布式時(shí)間同步算法,在傳統(tǒng)的同步算法中,節(jié)點(diǎn)只能在控制幀階段接入網(wǎng)絡(luò),需要的時(shí)間較長(zhǎng),同時(shí)只是保證在同步時(shí)刻精度較高。所以本文提出了改進(jìn)方法,使得節(jié)點(diǎn)在網(wǎng)絡(luò)中任何階段都能進(jìn)行入網(wǎng)操作,大大減少了節(jié)點(diǎn)入網(wǎng)的時(shí)延。改進(jìn)算法還在非周期同步期間對(duì)時(shí)鐘漂移進(jìn)行了估計(jì),并對(duì)時(shí)間進(jìn)行調(diào)整,獲得了更高的同步精度。仿真結(jié)果顯示改進(jìn)后的算法節(jié)點(diǎn)入網(wǎng)時(shí)延縮短很多,同步算法的收斂速度更快,可以在達(dá)到同樣的時(shí)間同步精度下可以延長(zhǎng)同步周期,從而減少控制包的交互,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.
【學(xué)位授予單位】：電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TN929.5

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