车载环境下无线接入系统中EDCA方式的应用-毕业论文.doc

延 边 大 学 二〇一二年六月摘 要 近年来，随着汽车工业的普及，私家车数量的激增，道路拥塞的日益严重，交通事故的频发，以及各式各样车载设备的不断涌现，车载通信领域的研究引起了人们极大的关注。如何创建高性能、安全的车载通信网络给无线研究者们提出了新的挑战。然而，已提出的车载环境下无线接入（WAVE）技术仍存在一些不足。 本文首先介绍了WAVE的概念及现有的多信道MAC机制，其次阐述了EDCA（Enhanced Distributed Channel Access）方式，即增强型分布式信道访问。随后提出引入EDCA方式能够在一定程度上提高系统性能及服务质量（QoS），并实现在整个CCH间隔中即时传送安全信息（Safety Information），从而更大程度上满足人们对车载通信Distributed Coordination Function）方式，满足了以上要求。 关键词：车载环境下无线接入；增强型分布式信道访问；媒体接入控制；服务质量 Abstract With the prevalence of Vehicle Industry, the booming number of private cars, the severe circumstance of congested traffic, the frequent occurrence of traffic accidents, and the continuous improvement of vehicular equipments, the area of Vehicular Communication arouse our strong attention in the recent couple of years. How to build the Vehicular Communication Network with high performance and safety gives the researchers, whom focus on wireless area, a brand new challenge. Nevertheless, the given WAVE (Wireless Access in Vehicular Environments) technique still has some imperfections. In this paper, we introduced the conception of WAVE and Multi-channel MAC Mechanism. Then, we describe the EDCA mode, that is, Enhanced Distributed Channel Access. Later, we bring EDCA to the system which can improve the performance and QoS of WAVE system, also realize the immediate Safety-Information transmission in the entire CCH Interval. Thus, it can satisfy the increasing demands of Vehicular Communication. In the WAVE system, we need high QoS and also the realization of the immediate Safety-Information transmission in the entire CCH Interval. Thus, we analyzed the principle and advantages of EDCA, and then we satisfied the above requirements by introducing the EDCA mode to replace the current DCF (Distributed Coordination Function) mode of WAVE. Keywords: Wireless Access in Vehicular Environments; Enhanced Distributed Channel Access; Media Access Control; QoS 目 录 摘 要 I Abstract II 引 言 1 第一章 绪论 2 1.1 课题背景 2 1.2车载环境下无线接入技术的研究现状 3 1.3 研究目的和意义 4 第