基于RoF-DAS的车载网络信道分配机制研究

发布时间：2018-03-16 22:39

本文选题：RoF-DAS结构　切入点：车载网络　出处：《西安电子科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：近些年智能交通系统(ITS)在减少交通负荷,保证交通安全,提高运输效率方面,取得了显著的成就,得到各国广泛的关注。车载无线网络作为智能交通管理系统中一项重要技术,不仅支持车辆间安全信息的传递,而且支持车辆与智能交通控制中心进行实时数据交互,包括控制中心发布实时路况信息和交通预警信息等,以及车内用户宽带无线接入互联网,获取多媒体资讯等。车载网络的研究面临着车辆移动性高、网络环境复杂、车辆不断增长的业务带宽需求所带来的挑战,随着车辆数量的日益增多,车辆之间的竞争和干扰导致车载网络通信性能加剧恶化。为了满足不断提高的网络通信性能要求,降低网络中的干扰,亟需优化车载网络中的信道接入机制和信道资源分配管理。为解决上述问题,本文提出了一种基于车辆环境下无线接入和光载射频(RoF)技术融合的车载网络架构—基于RoF技术的分布式天线系统(DAS)的车载无线网络结构,满足车内用户无处不在的信息需求和越来越丰富的业务需求。本文针对基于RoF-DAS结构的车载网络,提出了一种集中式多信道接入机制(CCM),该机制结合了车辆分簇的思想,分为簇内无竞争通信协议和簇间竞争通信协议。首先根据车辆节点相似度和节点度的快速聚类分簇算法,将车辆划分簇群并从中选出簇头车辆。簇头车辆配置两个无线收发器,分别工作在簇内信道上和簇间信道上,簇内成员车辆则工作在簇头车辆选择的簇内信道上。其次为了限制簇内车辆的无序竞争,提供公平的信道接入,簇内成员车辆以轮询的方式传输安全类业务,在簇头划分的时隙内以时分多址接入的方式传输非安全类业务。簇头车辆与中心控制站(CCS)和其他簇头之间的簇间通信采用灵活地基于竞争的接入方式。针对基于RoF-DAS的车载无线网络,本文设计了一套信道分配机制,包含两个部分:簇内信道分配和簇间信道分配。考虑到车辆行驶过程中频繁地切换接入远端接入天线(RAU),设计了一种基于路况信息划分RAU区群机制,将多个RAU天线合并连接一个射频信号处理单元(RFSP),降低车辆切换RFSP的频率。簇内信道分配机制:簇头车辆之间通过广播来交互信息构建局部分配图,根据信道的干扰度动态地选择簇内信道。簇间信道分配机制结合效用函数概念,以簇群的效用值为指标,基于网络全局效用值动态分配簇间信道,提高网络负载公平性。最后,本文基于OPNET仿真平台,对基于RoF-DAS的车载无线网络进行建模,对本文所提出的信道分配算法进行了仿真分析,结果表明本算法与传统的车载网络中基于测量的分布式信道分配算法相比,在网络整体性能车辆节点吞吐量、时延、丢包率性能均有较为明显的提升,同时对热点区域性能改善尤为明显。
[Abstract]:In recent years, Intelligent Transportation system (its) has made remarkable achievements in reducing traffic load, ensuring traffic safety and improving transportation efficiency. It not only supports the transmission of safety information among vehicles, but also supports the real-time data exchange between vehicles and its, including the release of real-time road condition information and traffic warning information by the control center. As well as broadband wireless access to the Internet, access to multimedia information and so on. The research of vehicular network is faced with the challenges brought by the high mobility of vehicles, complex network environment and the growing business bandwidth requirements of vehicles. With the increasing of the number of vehicles, the competition and interference between vehicles make the performance of vehicular network communication worse. In order to meet the requirements of continuous improvement of network communication performance, reduce the interference in the network. In order to solve the above problems, it is urgent to optimize the channel access mechanism and channel resource allocation management in vehicular network. In this paper, a vehicle-borne wireless network architecture based on the combination of wireless access and optical radio frequency (RF) technology in vehicle environment is proposed, which is based on the distributed antenna system (Das) based on RoF technology. This paper presents a centralized multi-channel access mechanism based on RoF-DAS, which combines the idea of vehicle clustering. Firstly, according to the fast clustering algorithm of vehicle node similarity and node degree, vehicles are divided into cluster groups and cluster head vehicles are selected. Cluster head vehicles are configured with two wireless transceivers. On the intra-cluster channel and inter-cluster channel respectively, the member vehicles in the cluster work on the intra-cluster channel selected by the cluster-head vehicle. Secondly, in order to limit the out-of-order competition of the vehicle in the cluster, it provides fair channel access. The member vehicles in the cluster transmit security services by polling. Non-secure traffic is transmitted by time division multiple access (TDMA) in the time slots divided by cluster heads. The communication between cluster head vehicles and CCS (central control station) and other cluster heads is based on flexible competition-based access. RoF-DAS 's vehicular wireless network, In this paper, a channel allocation mechanism is designed. It consists of two parts: Intra-cluster channel assignment and inter-cluster channel allocation. Considering the frequent switching of access to remote access antenna during vehicle driving, a RAU cluster mechanism based on road condition information is designed. Multiple RAU antennas are combined with one RF signal processing unit to reduce the frequency of vehicle switching RFSP. According to the interference degree of the channel, the intra-cluster channel is dynamically selected. The inter-cluster channel allocation mechanism combines with the concept of utility function, taking the utility value of the cluster as the index, and dynamically allocates the inter-cluster channel based on the global utility value of the network to improve the network load fairness. Based on the OPNET simulation platform, the vehicle wireless network based on RoF-DAS is modeled, and the channel allocation algorithm proposed in this paper is simulated and analyzed. The results show that compared with the traditional distributed channel allocation algorithm based on measurement, the proposed algorithm can improve the throughput, delay and packet loss performance of vehicle nodes. At the same time, the performance improvement of hot spot area is especially obvious.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U495;U463.67

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