發(fā)布時間：2018-01-07 14:16

  本文關鍵詞：車聯(lián)網(wǎng)V2I通信媒體接入控制技術研究　出處：《哈爾濱工業(yè)大學》2014年博士論文　論文類型：學位論文

  更多相關文章： V2I通信 速率控制 DCF建模 接入控制 模糊Q學習

【摘要】：我國是全球最大的汽車生產國和消費國,車輛已成為城市的重要組成部分。隨著我國經濟的發(fā)展,城市人口不斷增加,在百萬人口以上的大城市里,交通擁堵、車輛事故、環(huán)境污染已成為日常生活中一道亟待解決的難題。目前,世界各國都在積極探尋提高交通效率,使城市交通向智能化演進的解決方案。在這樣的背景下,車聯(lián)網(wǎng)技術應運而生。這種無線通信技術可以使車輛實現(xiàn)實時交通信息獲取、路線規(guī)劃、變換車道預警、碰撞預警、互聯(lián)網(wǎng)接入等智能駕駛功能,從而改變傳統(tǒng)的駕駛概念,在現(xiàn)有城市規(guī)劃的基礎上提高城市交通的運行效率。簡而言之,車聯(lián)網(wǎng)將通信技術融入了車輛、交通工程領域,通過環(huán)境感知、信息交互、信息整合實現(xiàn)傳統(tǒng)工業(yè)的跨越式發(fā)展。車聯(lián)網(wǎng)是以約定的通信協(xié)議和數(shù)據(jù)交互標準,進行無線通信和信息交換的網(wǎng)絡。目前,學術領域主要將車聯(lián)網(wǎng)技術分為兩類:車輛與路邊基礎設施(V2I,Vehicle to Infrastructure)的通信和車輛間(V2V,Vehicle to Vehicle)的通信。其中,V2I通信允許車輛在行駛過程中與路邊基礎設施(RSU,Road Side Unit)進行數(shù)據(jù)交換,可以獲得所處區(qū)域乃至整個城市的交通信息,在信息總體整合的基礎上對每個終端提供相應的駕駛指導和預警服務,在支持業(yè)務種類方面比V2V通信更具有優(yōu)勢。因此,V2I通信一直是智能交通的重點研究領域,近年來得到了大量關注�；谏鲜隹紤],本文的研究內容主要針對V2I通信。無線通信的媒體接入控制子層(MAC,Media Access Control sublayer)提供媒體接入控制功能,并對物理層(PHY,PHYsical layer)起到向下控制作用,媒體接入控制協(xié)議決定了能否對信道資源進行高效的調度,保障服務質量(Qo S,Quality of Service)。V2I通信的PHY層和MAC層采用IEEE 802.11p協(xié)議實現(xiàn)。然而,IEEE 802.11系列協(xié)議的設計初衷主要面向室內低移動性用戶,提供盡力而為型通信服務。如果將其拓展到車載通信領域,現(xiàn)有的MAC層協(xié)議存在諸多問題,并且無法提供Qo S保障。針對上述問題,本文對V2I通信的MAC層媒體接入控制技術進行了研究,重點著眼于V2I通信速率控制、基于多用戶多速率場景的MAC層DCF性能建模以及引申的RSU部署策略、稀疏部署RSU場景下安全類業(yè)務Qo S保障的自適應接入控制。本文首先研究了IEEE 802.11p協(xié)議PHY及MAC層的關鍵技術,為后文的工作提供了理論基礎。對于PHY層,主要研究了基于OFDM的八種多載波調制編碼方式的空口參數(shù),并分析了信道條件對誤碼率、誤包率、通信傳輸速率的影響。針對MAC層,主要研究了幾種重要的MAC層數(shù)據(jù)單元的幀結構以及幾種常用的信道訪問機制�？紤]到本文研究主要建立于仿真分析,無線信號的傳輸模型是否準確至關重要。傳統(tǒng)的針對IEEE 802.11協(xié)議信道建模的研究中,通�？紤]通信節(jié)點處于靜止或低速運動狀態(tài)。應用于V2I通信場景時,由于終端具有較高的移動性,信號的頻率選擇性衰落、多普勒頻移和多徑傳輸?shù)葐栴}勢必對信號傳輸帶來額外的影響。因此,本文對V2I通信場景下的信號傳輸進行了路測實驗。實驗結果表明,對數(shù)信號模型可以較好地反映V2I通信場景的信號傳輸特性,為后文的仿真提供了理論依據(jù)。IEEE 802.11p協(xié)議中對PHY層提供了多速率支持,以保障不同信道條件下的通信質量,但并沒有指定MAC層速率選擇及切換的方案。V2I通信場景中通信節(jié)點移動性較高,信號具有快速時變特性。另外,受限于IEEE 802.11網(wǎng)絡覆蓋范圍較小,通信節(jié)點駐留時間往往較短。移動節(jié)點在接近繼而遠離路邊基站的過程中,接收信號強度在經歷短時間的逐步上升后將馬上轉為衰落趨勢。針對以上問題,本文提出了一種具有快速信道響應特性的速率控制算法,解決了現(xiàn)有速率控制算法應用于V2I通信時難以兼顧信道響應速度及通信誤碼率的問題。仿真結果從吞吐量、時延、誤包率三個方面綜合論證了本文提出的速率控制算法比現(xiàn)有的主流算法更加適用于V2I通信。根據(jù)IEEE 802.11p MAC層的共享信道機制,網(wǎng)絡性能與在網(wǎng)用戶數(shù)直接相關。V2I通信的網(wǎng)絡規(guī)劃應當在滿足安全類業(yè)務Qo S需求的前提下充分利用無線資源,避免頻譜資源的浪費。因此,如何設計高效的V2I通信網(wǎng)絡RSU部署方案,使車載終端能夠無縫接入,并保障業(yè)務的Qo S需求具有重要的實際意義。針對這一問題,本文首先推導了V2I通信在多用戶多速率場景下的時延及吞吐量的數(shù)學模型。在此基礎上,本文提出了極限交通流密度條件下Qo S保障的RSU接入半徑理論界,進而提出了面向安全類業(yè)務的RSU無縫覆蓋部署策略,解決了V2I通信的Qo S保障問題�？紤]到在城市非熱點地區(qū),RSU必然不能大規(guī)模部署。隨著交通流密度的上升,網(wǎng)絡負載勢必會急劇增大,導致接入控制問題隨之凸顯。因此,對于稀疏部署RSU場景的V2I通信網(wǎng)絡,制定合理的接入控制策略具有重要的實際應用價值。針對上述問題,本文提出了一種基于模糊Q學習的V2I通信接入控制算法,解決了稀疏部署RSU場景下V2I通信安全類業(yè)務的Qo S保障問題。該算法具有自適應的學習能力,不需要添加信道模型、網(wǎng)絡參數(shù)、交通參數(shù)等先驗知識,具有優(yōu)秀的普適性。仿真結果表明,該算法可以兼顧網(wǎng)絡的承載能力及覆蓋范圍,在最大限度保障安全類業(yè)務Qo S的前提下,使非安全類業(yè)務盡可能接入,從而使頻譜資源得到充分利用。
[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.

【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：U495;TP391.44;TN929.5
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本文編號：1392900