车联网V2I通信媒体接入控制技术研究

发布时间：2018-01-07 14:16

  本文关键词：车联网V2I通信媒体接入控制技术研究　出处：《哈尔滨工业大学》2014年博士论文　论文类型：学位论文

  更多相关文章： V2I通信 速率控制 DCF建模 接入控制 模糊Q学习

【摘要】：我国是全球最大的汽车生产国和消费国,车辆已成为城市的重要组成部分。随着我国经济的发展,城市人口不断增加,在百万人口以上的大城市里,交通拥堵、车辆事故、环境污染已成为日常生活中一道亟待解决的难题。目前,世界各国都在积极探寻提高交通效率,使城市交通向智能化演进的解决方案。在这样的背景下,车联网技术应运而生。这种无线通信技术可以使车辆实现实时交通信息获取、路线规划、变换车道预警、碰撞预警、互联网接入等智能驾驶功能,从而改变传统的驾驶概念,在现有城市规划的基础上提高城市交通的运行效率。简而言之,车联网将通信技术融入了车辆、交通工程领域,通过环境感知、信息交互、信息整合实现传统工业的跨越式发展。车联网是以约定的通信协议和数据交互标准,进行无线通信和信息交换的网络。目前,学术领域主要将车联网技术分为两类:车辆与路边基础设施(V2I,Vehicle to Infrastructure)的通信和车辆间(V2V,Vehicle to Vehicle)的通信。其中,V2I通信允许车辆在行驶过程中与路边基础设施(RSU,Road Side Unit)进行数据交换,可以获得所处区域乃至整个城市的交通信息,在信息总体整合的基础上对每个终端提供相应的驾驶指导和预警服务,在支持业务种类方面比V2V通信更具有优势。因此,V2I通信一直是智能交通的重点研究领域,近年来得到了大量关注。基于上述考虑,本文的研究内容主要针对V2I通信。无线通信的媒体接入控制子层(MAC,Media Access Control sublayer)提供媒体接入控制功能,并对物理层(PHY,PHYsical layer)起到向下控制作用,媒体接入控制协议决定了能否对信道资源进行高效的调度,保障服务质量(Qo S,Quality of Service)。V2I通信的PHY层和MAC层采用IEEE 802.11p协议实现。然而,IEEE 802.11系列协议的设计初衷主要面向室内低移动性用户,提供尽力而为型通信服务。如果将其拓展到车载通信领域,现有的MAC层协议存在诸多问题,并且无法提供Qo S保障。针对上述问题,本文对V2I通信的MAC层媒体接入控制技术进行了研究,重点着眼于V2I通信速率控制、基于多用户多速率场景的MAC层DCF性能建模以及引申的RSU部署策略、稀疏部署RSU场景下安全类业务Qo S保障的自适应接入控制。本文首先研究了IEEE 802.11p协议PHY及MAC层的关键技术,为后文的工作提供了理论基础。对于PHY层,主要研究了基于OFDM的八种多载波调制编码方式的空口参数,并分析了信道条件对误码率、误包率、通信传输速率的影响。针对MAC层,主要研究了几种重要的MAC层数据单元的帧结构以及几种常用的信道访问机制。考虑到本文研究主要建立于仿真分析,无线信号的传输模型是否准确至关重要。传统的针对IEEE 802.11协议信道建模的研究中,通常考虑通信节点处于静止或低速运动状态。应用于V2I通信场景时,由于终端具有较高的移动性,信号的频率选择性衰落、多普勒频移和多径传输等问题势必对信号传输带来额外的影响。因此,本文对V2I通信场景下的信号传输进行了路测实验。实验结果表明,对数信号模型可以较好地反映V2I通信场景的信号传输特性,为后文的仿真提供了理论依据。IEEE 802.11p协议中对PHY层提供了多速率支持,以保障不同信道条件下的通信质量,但并没有指定MAC层速率选择及切换的方案。V2I通信场景中通信节点移动性较高,信号具有快速时变特性。另外,受限于IEEE 802.11网络覆盖范围较小,通信节点驻留时间往往较短。移动节点在接近继而远离路边基站的过程中,接收信号强度在经历短时间的逐步上升后将马上转为衰落趋势。针对以上问题,本文提出了一种具有快速信道响应特性的速率控制算法,解决了现有速率控制算法应用于V2I通信时难以兼顾信道响应速度及通信误码率的问题。仿真结果从吞吐量、时延、误包率三个方面综合论证了本文提出的速率控制算法比现有的主流算法更加适用于V2I通信。根据IEEE 802.11p MAC层的共享信道机制,网络性能与在网用户数直接相关。V2I通信的网络规划应当在满足安全类业务Qo S需求的前提下充分利用无线资源,避免频谱资源的浪费。因此,如何设计高效的V2I通信网络RSU部署方案,使车载终端能够无缝接入,并保障业务的Qo S需求具有重要的实际意义。针对这一问题,本文首先推导了V2I通信在多用户多速率场景下的时延及吞吐量的数学模型。在此基础上,本文提出了极限交通流密度条件下Qo S保障的RSU接入半径理论界,进而提出了面向安全类业务的RSU无缝覆盖部署策略,解决了V2I通信的Qo S保障问题。考虑到在城市非热点地区,RSU必然不能大规模部署。随着交通流密度的上升,网络负载势必会急剧增大,导致接入控制问题随之凸显。因此,对于稀疏部署RSU场景的V2I通信网络,制定合理的接入控制策略具有重要的实际应用价值。针对上述问题,本文提出了一种基于模糊Q学习的V2I通信接入控制算法,解决了稀疏部署RSU场景下V2I通信安全类业务的Qo S保障问题。该算法具有自适应的学习能力,不需要添加信道模型、网络参数、交通参数等先验知识,具有优秀的普适性。仿真结果表明,该算法可以兼顾网络的承载能力及覆盖范围,在最大限度保障安全类业务Qo S的前提下,使非安全类业务尽可能接入,从而使频谱资源得到充分利用。
[Abstract]:China is the world's largest automobile production and consumption country, vehicles have become an important part of the city. With the development of China's economy, city population increasing, the big city in a population of over 1 million, traffic congestion, traffic accidents, environmental pollution has become the daily life of a problem to be solved urgently. At present, many countries in the world are actively seeking solutions to improve traffic efficiency, traffic to the city of intelligent evolution. In this context, as a vehicle networking technology. The wireless communication technology can realize real-time traffic information acquisition, route planning of the vehicle lane change warning, collision warning, Internet access and other intelligent driving function thus, to change the traditional concept of driving, improve the efficiency of city traffic based on the existing city planning. In short, the car will be networked communication technology into the vehicle, traffic engineering Through the field environmental perception, information exchange, information integration to achieve leapfrog development of the traditional industry. The car networking is to the agreed communication protocol and data exchange standard network, wireless communication and information exchange. At present, the academic field mainly car networking technology are divided into two types: vehicles and roadside infrastructure (V2I, Vehicle to Infrastructure) and inter vehicle communication (V2V, Vehicle to Vehicle) communication. Among them, V2I communication allows the running vehicles and roadside infrastructure (RSU Road, Side Unit) to exchange data, and can obtain the traffic information area and even the whole city, to provide the corresponding driving guidance and warning service for each terminal on the basis of the information on the overall integration, in support of business types has more advantages than the V2V communication. Therefore, V2I communication has been a research focus in the field of intelligent transportation, in recent years has been a big The amount of attention. Based on the above considerations, this study mainly aims at the V2I communication. Wireless communication media access control layer (MAC, Media Access Control sublayer) provides media access control function, and the physical layer (PHY, PHYsical layer) to play down the control effect, media access control protocol can efficiently determine the scheduling of channel resources, guarantee the quality of service (Qo S, Quality of Service).V2I communication PHY layer and MAC layer using the IEEE 802.11p protocol. However, the original design of IEEE 802.11 series protocol mainly for indoor low mobility users, to provide best effort communication services. If it is extended to the field of vehicular communication, MAC protocol the existing problems, and can not provide Qo guarantee of S. Aiming at the above problems, this paper on the V2I communication MAC layer media access control technology is studied, focusing on the V2I. The letter rate control, MAC layer DCF performance modeling of multi user multi rate scene and extended RSU deployment strategy based on adaptive access control security service Qo RSU sparse deployment scenarios S security. This paper studies the key technologies of IEEE PHY and MAC 802.11p protocol layer, to provide a theoretical basis for the later work. For PHY, mainly studies the interface parameters of eight kinds of multi carrier modulation encoding based on OFDM, and analyzes the conditions on the channel error rate, packet error rate, communication transmission rate. For the MAC layer, mainly studied several important MAC layer data unit frame structure and several commonly used channel access mechanism considering this study is mainly based on the simulation analysis, the wireless signal transmission model's accuracy is crucial. Traditional researches on IEEE 802.11 protocol channel modeling, communication node is usually considered Stationary or slow motion. Used in V2I communication scenario, because the terminal has high mobility, frequency selective fading signals, Doppler frequency shift and multi-path transmission will bring additional impact on signal transmission. Therefore, the signal transmission of V2I communication scenarios of road test experiments. The log, the signal model can reflect the signal transmission characteristics of V2I communication scenarios, the simulation for the.IEEE 802.11p protocol provides a theoretical basis for the PHY layer provides multi rate support, to ensure the communication quality under different channel conditions, but did not specify the MAC communication node mobility higher layer rate selection and handoff scheme.V2I communication scenarios, signals with fast time-varying characteristics. In addition, due to the IEEE 802.11 network coverage is small, the communication nodes are short dwell time. The mobile node in the The process of close and away from the roadside base station, after a short time will gradually rise to the decline trend of the received signal strength. To solve the above problems, this paper proposes a rate control algorithm has the characteristics of fast response channel, solve the existing rate control algorithm applied in V2I communication is difficult to balance the channel response speed and BER problem. The simulation results from the throughput, delay and packet error rate of the three aspects of comprehensive demonstration rate control algorithm is proposed in this paper is more suitable for V2I communication than the existing algorithm. According to the main mechanism of IEEE 802.11p MAC shared channel layer, network performance and should make full use of wireless resources in order to meet the demand of security service Qo S demand in network planning is directly related to the number of users of.V2I communication, to avoid the waste of spectrum resources. Therefore, how to design the V2I RSU efficient communication network The Department of the scheme, the vehicle terminal can be seamless access, has important practical significance and support business Qo S. To solve this problem, this paper presents a mathematical model of delay and throughput of V2I communication in multi-user multi rate scenarios. On this basis, this paper proposes a RSU access radius theory limit traffic flow the density of Qo under the condition of S guarantee, and puts forward the safety oriented business RSU seamless coverage deployment strategy to solve the security problem of S V2I communication Qo. Considering the non hot spots in the city, RSU will not increase with the current density of large-scale deployment. Through the network load will increase sharply, resulting in access control the problem will be highlighted. Therefore, for the deployment of RSU V2I communication network sparse scene, has important practical value to develop reasonable access control strategy. According to the above problems, this paper proposes a V2I access control algorithm based on fuzzy Q learning, to solve the security problem of S sparse deployment of RSU scene V2I communication security service Qo. This algorithm has adaptive learning ability, do not need to add the channel model, the network parameters, traffic parameters such as prior knowledge, general is excellent. The simulation results show that the the algorithm can take into account the capacity of the network and the coverage, in the premise of the maximum security service Qo S, the non security business as much as possible access, so that the spectrum resources are fully utilized.

【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：U495;TP391.44;TN929.5
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本文编号：1392900