發(fā)布時(shí)間：2018-03-09 05:03

  本文選題：車載網(wǎng)絡(luò)　切入點(diǎn)：節(jié)點(diǎn)移動(dòng)性　出處：《國防科學(xué)技術(shù)大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：車載自組織網(wǎng)絡(luò)(Vehicular Ad Hoc Networks)簡稱VANET。VANET被認(rèn)為在將來的智能交通系統(tǒng)的重要組成部分,被認(rèn)為通過整合ad hoc網(wǎng)絡(luò)、WLAN和蜂窩技術(shù)能夠提升交通安全和交通效率。在車載網(wǎng)絡(luò)中,裝備有專用短程通訊設(shè)備的車輛可以直接或間接地與其他車輛通信,也可以與路邊設(shè)施交換信息,基于此,車載網(wǎng)絡(luò)可以提供很多服務(wù),比如:車輛碰撞預(yù)警、實(shí)時(shí)交通情況報(bào)告等等。對于大多數(shù)基于車載網(wǎng)絡(luò)的應(yīng)用而言,端到端的數(shù)據(jù)通信傳輸?shù)难舆t時(shí)間和投遞率是制約應(yīng)用性能的主要瓶頸,這依賴于車輛的移動(dòng)性特征,特別是車輛高速移動(dòng)造成的網(wǎng)絡(luò)拓?fù)鋭?dòng)態(tài)變化,傳統(tǒng)的對于網(wǎng)絡(luò)拓?fù)涞难芯恐饕诶碚撃Ｐ?但理論模型依賴于很強(qiáng)的前提假設(shè),這與現(xiàn)實(shí)情況完全不符。隨著近年來大規(guī)模車輛實(shí)驗(yàn)的部署,為現(xiàn)實(shí)條件下車載網(wǎng)絡(luò)拓?fù)涞难芯刻峁┝丝赡�。本文基于舊金山和深圳的出租車軌跡數(shù)據(jù)集,對城市環(huán)境下車載網(wǎng)絡(luò)節(jié)點(diǎn)移動(dòng)性和網(wǎng)絡(luò)拓?fù)溥M(jìn)行分析,并提出了路由策略。我們首先對數(shù)據(jù)集和數(shù)據(jù)特征做了簡單介紹,并給出了節(jié)點(diǎn)移動(dòng)性特征的重要指標(biāo):聯(lián)系間隔時(shí)間、剩余聯(lián)系間隔時(shí)間及節(jié)點(diǎn)的度中心性。我們發(fā)現(xiàn)聯(lián)系間隔時(shí)間的分布大致符合指數(shù)分布特征。接著我們給出了節(jié)點(diǎn)度的分布特征和兩跳鄰居節(jié)點(diǎn)的度的一些特征,最后給出了等待時(shí)間降低比例(WTR)和好點(diǎn)比例(GNR)的定義,并利檢驗(yàn)了三種簡單策略下的WTR和GNR,分析了節(jié)點(diǎn)的不確定性對車輛傳輸延遲的影響。接著我們將網(wǎng)絡(luò)抽象成為一個(gè)帶有時(shí)間戳的無向圖,利用數(shù)據(jù)集來探索了車輛連通分支的時(shí)空變化特征,我們發(fā)現(xiàn)整個(gè)網(wǎng)絡(luò)由大量的連通分支(Connected Component,CC)構(gòu)成,絕大多數(shù)CC中所包含的節(jié)點(diǎn)數(shù)目非常小,但是最大的CC包含了網(wǎng)絡(luò)中相當(dāng)大一部分節(jié)點(diǎn),甚至可以達(dá)到80%,而且在交通高峰和低潮時(shí)段最大CC的車輛數(shù)目變化并不明顯,進(jìn)一步,我們提出了連通分支穩(wěn)定性的概念,來衡量節(jié)點(diǎn)成員的變化程度,發(fā)現(xiàn)當(dāng)半徑足夠大的時(shí)候最大連通分支表現(xiàn)相當(dāng)穩(wěn)定,然后我們提出了連通分支位置獨(dú)立性的概念,找到了最大連通分支的覆蓋范圍,為靜態(tài)節(jié)點(diǎn)的部署提供了依據(jù)。最后我們引入了復(fù)雜網(wǎng)絡(luò)中的經(jīng)典算法k-核分解法,來找到了最大連通分支的k-核。最后我們設(shè)計(jì)了最先相遇K策略(FMK)和基于剩余相遇間隔時(shí)間的路由策略(RICT),并對路由策略的性能進(jìn)行測試,同時(shí)我們得出了端到端的數(shù)據(jù)傳輸與S-D節(jié)點(diǎn)對的初始地理位置是獨(dú)立的,比較發(fā)現(xiàn)RICT有著較好的性能。
[Abstract]:Vehicular Ad Hoc Networks (VANET.VANET) is regarded as an important component of the future intelligent transportation system. It is believed that the integration of ad hoc network and cellular technology can improve traffic safety and traffic efficiency. Vehicles equipped with special short-range communication equipment can communicate directly or indirectly with other vehicles, or can exchange information with roadside facilities. Based on this, vehicle-borne networks can provide many services, such as vehicle collision warning. For most applications based on vehicle network, the delay time and delivery rate of end-to-end data communication transmission are the main bottleneck of application performance, which depends on the mobility of vehicle. Especially the dynamic change of network topology caused by the high-speed movement of vehicle, the traditional research of network topology is mainly based on the theoretical model, but the theoretical model depends on a strong premise hypothesis. With the deployment of large scale vehicle experiments in recent years, it is possible to study the topology of vehicular network in real conditions. This paper is based on the taxi track data set in San Francisco and Shenzhen. This paper analyzes the mobility and network topology of vehicular network nodes in urban environment, and proposes a routing strategy. Firstly, we briefly introduce the data sets and data features. An important index of node mobility is given: contact interval time, We find that the distribution of the connection interval approximately accords with the exponential distribution. Then we give the distribution characteristics of the node degree and the degree of the two-hop neighbor node. At last, the author gives the definitions of waiting time reduction ratio (WTR) and good point ratio (GNR). We also test the WTR and GNR under three simple strategies and analyze the effect of node uncertainty on the vehicle transmission delay. Then we abstract the network into an undirected graph with a timestamp. Using the data set to explore the spatial and temporal characteristics of the connected branches of vehicles, we find that the whole network is composed of a large number of connected components CCs, and most of the nodes contained in CC are very small. However, the largest CC contains a large number of nodes in the network, and can even reach 80 percent. Moreover, the maximum CC number of vehicles in the rush and low tide periods does not change significantly. Further, we put forward the concept of stability of connected branches. When the radius is large enough, the maximum connected branch is quite stable. Then we put forward the concept of the location independence of the connected branch, and find the coverage of the maximum connected branch. Finally, we introduce the classical algorithm of k- kernel decomposition in complex networks. Finally, we design the first encounter K policy FMK) and the routing strategy based on the remaining encounter interval time, and test the performance of the routing policy. At the same time, we get that the end-to-end data transmission is independent of the initial geographic location of S-D node pairs, and it is found that RICT has better performance.
【學(xué)位授予單位】：國防科學(xué)技術(shù)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：U495;U463.67;TN929.5

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本文編號(hào)：1587077