多接口车联网可变带宽信道分配算法研究

This project focuses on the critical technologies for vehicular ad hoc networks(VANETs), which have emerged as an essentially new paradigm for the design of communication protocols, mobility models, and a variety of new services. This technology has its roots in on-board embedded sensors, wireless interface, embedded computers and protocols or algorithms for mobile ad hoc networks(MANETs), which enable vehicle-to-vehicle communications without communication infrastructure (e.g., wireless basestations). A fundamental yet open issue is addressed: how to promote the parallel transmission capability of wireless links and overall throughput in VANETs? To address the unique challenges presented by mobility-induced dynamic topology problem, a complimentary approach to variable bandwidth channel allocation technology in complicated transportation environment is employed. The project focuses on following issues: (1) Aiming at topological dynamics of multi-radio VANETs, to research descriptive approach of logical topology and construction method of link conflict graph. (2) Exploring the relationship of the high-speed mobility of vehicles and network connectivity, to research collision-free parallel transmission of links and semi-definite programing based link scheduling problem. (3) In order to lower the impact of topological dynamic on channel allocation, analyzing the characteristics of vehicle movement in urban traffic environment to develop geographic clustering strategy and construct off-line channel allocation scheme based on vehicle position bin-packing problem. (4) After determining the optimization goal, to research the method of initial network traffic distribution. Accordance with the coupling effect between routing and network traffic, to develop load-aware geo-routing scheme. (5) To develop strategies of evaluationa and simulation testbench that supports the practical deployment of variable bandwidth channel allocation technology in VANETs. As VANETs advance large-scale networks, this project addresses an acute and timely demand for exploring fundamental principles of variable bandwidth allocation problem, which have not been studied systematically in VANETs, but have tremendous impact on vehicular communication system designs, optimization techniques for network performance, and modeling of VANETs.

满足交通环境应用要求的可变带宽信道分配技术是车联网(VANET: Vehicular ad hoc networks)成功部署的关键一环。本研究针对车辆运动速度快、拓扑随路网分布的实际情况，提出满足车联网动态拓扑特性的可变带宽信道分配方案。首先，研究多接口车联网逻辑拓扑描述方法和冲突图构建策略。根据动态拓扑和连通性等要素间的制约关系，研究链路无冲突并行传输问题及半定规划链路调度方法。通过挖掘城市交通车辆运动特点，提出车联网地理成簇策略，并在此基础上构建基于车辆位置装箱的离线信道分配机制，以降低拓扑动态特性对信道分配的影响。在确定带宽分配优化目标的基础上研究网络初始数据流分配方法，并针对路由与网络负载之间的耦合关系研究链路负载感知的地理路由策略，尽量维持优化的网络负载分布。最后，构建车联网可变带宽信道分配技术的评价策略和仿真验证平台，对提出的方案进行评估，促进在车联网中的可靠部署。

可变带宽信道分配技术为车联网的数据高效传输提供了技术基础，为车联网各项应用实际部署的重要保证。本课题以可变带宽信道分配技术为基础，提出城市交通环境下车联网数据分发方案。主要开展了以下四个方面的工作：(1)针对车联网节点移动速度快网络拓扑频繁变化的问题，研究车联网逻辑拓扑描述方法和冲突图构建策略。将车辆无线接口作为冲突图的节点，在获得车辆间距的基础上通过奇异值分解建立网络冲突图，从而具备多接口车联网的描述能力。(2)研究车联网无冲突链路调度方法。具体研究了无冲突链路并行传输的信道分配算法，并在冲突集内建立了无冲突链路调度策略。 (3) 研究移动环境下移动节点协作定位技术，为车联网部署基于位置的服务提供技术支撑。具体研究移动节点运动过程的距离数据分时采样机制，避免节点高速运动引起的定位延迟。研究位置估计结果的优化机制，设计了基于梯度搜索的位置优化算法。(4) 研究城市环境下车联网数据分发策略。建立了交通路段时延模型，在时延模型的基础上研究了交通路网时延下界估计方法，为数据包在路口的转发决策提供依据。同时构建了车辆轨迹匹配度的下一跳车辆选择机制，和降低副本的数据包转发方案，此外，建立了数据包在交通路口的转发概率模型和V2I数据传输跨层优化策略，为数据转发提供理论指导。