车载自组网中安全信息的拥塞优化方法研究

发布时间：2018-01-18 13:06

本文关键词：车载自组网中安全信息的拥塞优化方法研究　出处：《浙江大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着现代工业不断发展,汽车保有量快速增长,然而交通事故的发生率也随之急剧升高。车载自组网作为智能交通系统的核心部分,在提高车辆在道路上行驶时的安全性、提高交通资源的利用率和提供信息服务等方面起到重要作用。因为直接与人身财产安全相关,车载自组网中面向安全的信息传递对可靠性有较高要求。然而在交通拥堵的环境中,容易因广播消息数过多而形成信道拥塞,使面向安全应用的可靠性受到极大影响。为了降低信道拥堵情况出现的频率,本文针对面向安全应用中的周期性安全消息和突发事件告警消息,提出了优化方案。对于周期性安全消息的优化步骤包括:(1)采用基于载波侦听机制的信道忙闲比参数作为对节点网络状态的评判标准;(2)在节点网络状态判定为拥堵时,令该节点参与最大功率广播权的竞争,使得周边节点获取拥堵消息的同时又避免加重网络负载;(3)对于普通节点而言,则根据其周边节点的网络状态按照功率调整曲线调整其功率;(4)综合考虑发射功率和邻居节点数,灵活快速的调整功率值至合适值。对于告警消息,在Slotted 1-persistence算法基础上进行优化:(1)基于节点的邻居列表数据,估计周边车辆密度;(2)根据车辆密度情况,动态的划分路段数,降低节点转发消息时的平均等待时间;(3)根据信道忙闲比参数设置各转发节点的转发概率,在信道忙碌状态下,控制转发节点数量,从而降低信道拥堵并确保消息接受的成功率。通过使用SUMO交通环境仿真器和OMNET++通信网络仿真器,搭建车载自组网仿真环境并对改进算法进行了仿真和评估。仿真结果表明:(1)针对周期性安全消息提出的动态功率算法,在分组投递率和分发延时方面的性能均明显优于固定功率算法;(2)针对告警信息提出的多跳改进算法,相对于于传统的Slotted1-persistence算法,在保证了安全消息分组投递率的情况下,降低了分发延时和广播冗余度。
[Abstract]:With the continuous development of modern industry, the number of vehicles has increased rapidly, but the incidence of traffic accidents has also increased sharply. The vehicle-borne ad hoc network is the core part of the intelligent transportation system. It plays an important role in improving the safety of vehicles on the road, improving the utilization rate of traffic resources and providing information services, because it is directly related to personal and property safety. Security oriented information transmission in vehicular ad hoc networks requires high reliability. However, in the traffic congestion environment, it is easy to form channel congestion due to the excessive number of broadcast messages. In order to reduce the frequency of channel congestion, this paper aims at periodic security messages and emergency alarm messages in security-oriented applications. An optimization scheme is proposed. The optimization steps for periodic security messages include: 1) the channel busy / idle ratio parameters based on carrier detection mechanism are adopted as the criteria for judging the network status of nodes. (2) when the network state of the node is judged as congested, the node is allowed to participate in the competition of the maximum power broadcasting right, so that the peripheral node can obtain the congestion information while avoiding the aggravating network load; (3) for ordinary nodes, the power is adjusted according to the power adjustment curve according to the network state of the peripheral nodes. 4) considering the transmission power and the number of neighbor nodes, the power value can be adjusted to the appropriate value flexibly and quickly. Based on the Slotted 1-persistence algorithm, the neighbor list data of the nodes are optimized to estimate the density of the surrounding vehicles. (2) according to the density of the vehicle, the number of sections is divided dynamically to reduce the average waiting time when the node transmits the message; The forwarding probability of each forwarding node is set according to the parameters of channel busy / idle ratio, and the number of forwarding nodes is controlled in the busy state of the channel. This reduces channel congestion and ensures the success rate of message acceptance by using SUMO traffic environment emulators and OMNET communication network emulators. The simulation results show that the proposed dynamic power algorithm is based on periodic security messages. The performance of packet delivery rate and distribution delay is better than that of fixed power algorithm. Compared with the traditional Slotted1-persistence algorithm, the improved multi-hop algorithm for alarm information can guarantee the packet delivery rate of secure messages. The distribution delay and broadcast redundancy are reduced.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.5;U495

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