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类型 基础研究 预答辩日期 2018-01-03
开始(开题)日期 2015-06-10 论文结束日期 2017-11-22
地点 中国无线谷2322会议室 论文选题来源 国家自然科学基金项目     论文字数 6 (万字)
题目 车辆自组织网络无线接入若干算法研究
主题词 车辆自组织网络,时分复用,协议序列分配,淘汰竞争,自适应时隙分配
摘要 车辆自组织网络(Vehicular Ad Hoc Network,VANET)是智能交通系统(Intelligent Transportation Systems,ITS)的重要组成部分之一,承载了智能交通系统中大量关键的车辆安全应用和交通效率类应用,由于车辆自组织网络具有网络拓扑变化快、频谱资源有限和节点移动路径可预测等特点,其无线接入算法的设计极具挑战性。本学位论文从多信道可变间隔接入、协议序列分配、车辆用户分级接入和簇内服务信道资源分配4个方面对车载自组织网络的无线接入算法展开了研究。 论文的主要工作和创新之处如下: 1. 针对无线接入车载环境(Wireless Access in Vehicular Environments,WAVE)协议的碰撞概率较大以及信道资源分配不合理这一特点,提出一种基于多轮淘汰竞争的多信道接入算法。该算法将控制信道间隔分为三个子阶段:路边单元广播阶段、安全消息广播阶段以及服务信道预约阶段。具体而言,在路边单元广播阶段,路边单元广播协调包告知周围的车辆节点其下一个阶段的广播时隙位置;在安全消息广播阶段,车辆节点基于路边单元的广播消息无碰撞地接入信道;在服务信道预约阶段,车辆节点通过基于多轮淘汰机制的竞争解决方案来减少传输碰撞概率,提高成功预约数,此外,采用一种基于轮空调度的车辆业务分级改进算法来处理该阶段不同优先级车辆用户的接入问题,高优先级车辆用户在淘汰过程的第一个轮次避开竞争,因而有更高的概率在整个竞争过程中胜出。考虑到网络的动态特性,所提多信道接入算法可以自适应地调整一个帧间隔内各个阶段的间隔大小和服务信道预约阶段的竞争轮数来提升服务信道吞吐量性能。理论分析与仿真结果表明所提算法可以充分利用控制信道和服务信道的资源,有效地降低服务信道预约阶段的碰撞概率,并且其服务信道饱和吞吐量性能要好于可变控制信道间隔(Variable CCH Interval,VCI)协议和WAVE协议。 2. 针对车辆自组织网络中协议序列的分配依赖于路边单元并且序列资源大量浪费的缺点,提出两种自适应序列分配方案。其中,矩形单元方案用于直线路段上车辆无冲突地占用序列,正六边形方案用于城市场景下车辆的自适应序列分配。本文研究了作为序列分配基础的广义质序列的和序列的性质,并给出了车辆节点生成单元标记以及自适应占用序列的具体算法。仿真结果表明所提两种方案相对于基于车辆节点所在位置的单一分配方案而言提升了网络的协议序列利用率和吞吐量性能。 3. 针对基于时分复用的车辆自组织网络的时隙浪费问题,提出一种基于双阶段时隙分配的车辆用户分级算法。该算法将车辆节点分为骨干节点和普通节点,在第一个阶段,所有车辆节点采用相同的时隙占用方式占有单个时隙;在第二个阶段,部分普通节点可以升级为骨干节点,骨干节点在该阶段占用更多的时隙。本文分别给出了双阶段时隙的占用方法以及节点的动态升级过程。此外,重点分析了所提算法的时隙利用率以及广播时延性能。理论分析与仿真结果表明所提算法在时隙利用率和广播时延上比单阶段单时隙占用算法具有更好的性能。 4. 针对车辆自组织网络分簇方案中服务信道资源浪费的问题,提出一种自适应服务信道时隙分配算法。该算法由时隙预分配算法和二次分配算法两部分组成。预分配算法中簇成员节点根据其在控制信道内占有的时隙位置预约部分服务信道时隙;二次分配算法中所有簇成员节点通过轮询方案对剩余的未预约时隙进行占用,考虑到固定的簇成员用户二次分配调度方式会持续降低部分用户的时隙占有率,采用一种基于轮换机制的改进算法,使得簇成员节点的二次分配过程根据簇稳定间隔数进行自适应调度。仿真结果表明所提自适应服务信道时隙分配算法可以充分地利用服务信道资源,而且能够保证簇内成员间的长期公平性。
英文题目 RESEARCH ON WIRELESS ACCESS ALGORITHMS FOR VEHICULAR AD HOC NETWORKS
英文主题词 Vehicular ad hoc networks, protocol sequence allocation, TDMA, elimination contention, adapative slot allocation
英文摘要 Vehicular ad hoc networks (VANETs) are playing an important role in Intelligent Transportation Systems (ITS), which undertake a large number of key vehicular safety and traffic efficiency applications. Wireless access design for VANETs is always a challenging work since VANETs have some special properties such as rapidly changing topology, limited spectrum resource and predictable moving path. In this dissertation, the wireless access algorithms of VANETs are carefully studied from four aspects: multi-channel access with changeable channel interval, protocol sequence allocation, vehicle differentiation access and intra-cluster service channel resource allocation. The main contents and innovations of this dissertation are shown as follows. 1. To overcome the weak points that collision probability is high and channel resource allocation is unreasonable in wireless access in vehicular environments (WAVE) protocol, a multi-round elimination contention based multi-channel access algorithm is proposed. In this algorithm, the control channel (CCH) interval is divided into three phases: roadside unit (RSU) broadcast phase, safety message broadcast phase and service channel (SCH) reservation phase. Specially, in the first phase, the RSU broadcasts coordination packets which include slot allocation information to vehicular nodes around; In the second phase, vehicular nodes carry out collision-free broadcast; In the third phase, vehicles contend with each other for SCH resource on the basis of the multi-round elimination contention process which could significantly decrease transmission collision probability and provide more successful reservations. Besides, a round-bye based vehicle traffic differentiation scheme is used to deal with multi-priority access problem in the third phase. Vehicles who have high priority can stay out of the contention in the first round of the elimination process, hence, they have high probability winning in the end. Considering the dynamic property of VANETs, the proposed algorithm can adaptively adjust the length of the CCH interval and the value of the round number for the improvement of the system throughput. Theoretical analysis and simulation results show that the proposed algorithm can take full use of the CCH and SCH resource, effectively decrease transmission collision probability in the SCH reservation phase, and exhibit its superiority in saturated throughput compared to the variable CCH interval (VCI) MAC and the WAVE MAC. 2. To overcome the drawbacks that protocol sequence allocation in VANETs heavily relies on the help of roadside units and that lots of sequence resource is wasted owing to the one-to-one scheme, two adaptive sequence allocation schemes are proposed. Specifically, the rectangle-cell (R-C) scheme is proposed for neighboring nodes to occupy sequences without overlapping on straight roads. Furthermore, the hexagon-cell (H-C) scheme is proposed to handle the sequence allocation problem on city roads. The sum of generalized prime sequences which builds the foundations for the proposed schemes is fully studied. Besides, the algorithms for vehicles to generate cell marks and occupy sequences without any inter-vehicle interference are given in detail. Simulation results show that both the R-C scheme and the H-C scheme can take full advantage of the sequence resource and exhibit their superiority in sequence utilization and throughput compared to the one-to-one scheme. 3. To overcome the slot wastage problem in traditional time division multiple access (TDMA) based VANETs, a two-phase based user differentiation algorithm (UDA) for slot allocation is proposed. Vehicular nodes in this algorithm are divided into two types: the backbone nodes and the ordinary nodes. In the first phase, every vehicular node tries to occupy one time slot with the same behavior, and at the end of the first phase based on the received broadcast packets during one frame part of the ordinary vehicular nodes can be upgraded to backbone nodes. During the second phase the backbone nodes carry out a greedy behavior to contend for more time slots while ordinary nodes give up slot contention. The slot occupation period and the dynamically backbone node selection strategy are given in detail. Moreover, the performance of average channel utilization and broadcast delay have been analyzed. Analysis and simulation results show that the proposed UDA has a better performance in the two indexes listed above compared to the one-to-one scheme without user differentiation. 4. To overcome the wick points that lots of SCH resource is wasted in cluster based VANETs, an adaptive SCH slot allocation algorithm is proposed. This algorithm is composed of two parts: slot pre-allocation period and slot reallocation period. In the first part, cluster members occupy SCH slots according to the position of the slot which has been reserved on the CCH. In the second part, cluster members contend with each other to occupy the unreserved slots via polling. Besides, an improvement algorithm which enables cluster members to occupy slots on the basis of the cluster stabilization time is proposed to deal with the problem that the resource of some cluster members will always be harmed due to the constant occupation order in the second part. Simulation results show that the proposed adaptive slot allocation algorithm can take full use of the SCH resource and exhibit a high level of long-term fairness among cluster members.
学术讨论
主办单位时间地点报告人报告主题
移动通信国家重点实验室 2015.6.29 无线谷1319会议室 Philippe Martins Spatial methods for planning and dimensioning of wireless systems
移动通信国家重点实验室 2015.10.16 无线谷1319会议室 杨伟豪 Cut-Set Bounds for Networks with Zero-Delay Nodes
移动通信国家重点实验室 2015.10.21 无线谷1319会议室 Gérard Memmi Data protection and fragmentation
移动通信国家重点实验室 2017.5.25 无线谷1319会议室 Wenzhan Song Fog Computing in Cyber-physical Systems and Security
课题组 2014.12.16 无线谷 茆意伟 VANET无线接入技术调研
课题组 2015.9.19 无线谷 茆意伟 车辆自组织网络p坚持时隙分配方案
课题组 2015.12.2 无线谷 茆意伟 车辆自组织网络协议序列分配框架
课题组 2016.5.5 无线谷 茆意伟 基于多轮竞争淘汰机制的车辆自组织网络多信道接入方案
     
学术会议
会议名称时间地点本人报告本人报告题目
IEEE WCNC 2016 2016.4.3-2016.4.6 卡塔尔多哈 VMR-MAC: A Multi-Round Contention based MAC Protocol for Vehicular Networks
IEEE WCNC 2017 2017.3.19-2017.3.23 美国旧金山 User Differentiation Scheme for Slot Allocation in Vehicular Networks
     
代表作
论文名称
Multi-round elimination contention-based multi-channel MAC scheme for vehicular ad hoc networks
User differentiation scheme for slot allocation in vehicular networks
 
答辩委员会组成信息
姓名职称导师类别工作单位是否主席备注
张顺颐 正高 教授 博导 南京邮电大学
蔡跃明 正高 教授 博导 解放军陆军工程大学
宋铁成 正高 教授 博导 东南大学
张在琛 正高 教授 博导 东南大学
张华 正高 教授 博导 东南大学
      
答辩秘书信息
姓名职称工作单位备注
燕锋 副高 副教授 东南大学