摘 要

物流业是我国国民经济的重要组成部分，集运输业，仓储业，货代业和信息业等产业为一体。在产业结构调整，转变经济发展模式和提高国民经济竞争力等方面有重要作用。

近年来我国的物流行业蓬勃发展，全球货运总量的80%左右都是由公路汽车运输完成的，由此可见公路汽车运输在我国以及世界物流运输业中仍占据主导地位。移动互联网的快速发展，大量物流设施通过配备传感器接入互联网，物流连接出现快速增长的态势。

物流行业的快速发展离不开社会发展中的大量软硬件的支持。智能交通系统

利用先进的科学技术使管理人员对于道路，车辆的状态能够获得详细的数据信息，随时随地的掌握具体的动态。智能交通系统以信息的收集、处理、发布、交换、分析、利用为主，为交通参与者提供全面的个性化服务。

伴随着智能交通系统的高速发展以及物流车队在行进过程中的协同通信对于信息的分享和传输提出了较高准确性和实时性的要求。因此，车载无线自组织网络的通信受到人们的广泛关注，在车载无线自组网中，隐藏终端是影响网络通信质量的主要因素，及时检测出隐藏的数据冲突，提高信息的共享价值，减少不必要的运输损失，提高运输的效率，减少运输成本成为了我国目前物流行业亟待解决的问题。

本文在详细介绍VANET的特点和隐藏终端问题的理论基础，对VANET中隐藏终端的产生的几种情况进行的具体的分析。同时向大家简单介绍下位图分析法的基本原理，在日常的车辆CAM广播中加入一个数据包包含位图信息，通过对比接收到数据包中位图信息的标记位，来判断当前的通信网络中是否存在隐藏的数据冲突。之后详细的介绍了不同的位图标记位所对应的不同情况以及其在物流车队行进过程中的具体运作，以已经接受到数据包来说，主要可以根据是否已产生通信缓存分为两类，提供一个认识和检测隐藏终端的新思路。

根据位图信息的对比方法，利用Visual Basic设计了一个在智能物流车队协同通信中的隐藏终端检测系统，主要实现了通信链路状态的实时查看，车辆节点通讯的全局状态，以及局部隐藏终端的判断以及历史数据查看等功能。实践证明，位图分析法能够准确有效的检测出在物流车队移动协同通信中的隐藏终端的存在，减少资源的浪费，增加信息传输的准确性和有效性。

关键词：隐藏终端；车载无线自组织网络；协同通信；位图分析法

Analysis and Research of Hidden Terminal Problem in Collaborative Communication of Intelligent Logistics Fleet

Abstract

As an important part of the national economy, logistics industry integrates transportation, warehousing, freight forwarding and information industries. It has played an important role in promoting industrial restructuring, transforming the mode of economic development and enhancing the competitiveness of the national economy.

In recent years, China's logistics enterprises have developed vigorously. The freight volume completed by road automobile transportation accounts for about 80% of the total global freight volume. Road automobile transportation still occupies a dominant position in China and the world's logistics transportation industry. With the rapid development of mobile internet, a large number of logistics facilities access the Internet through sensors, and logistics connections appear a rapid growth trend.

The rapid development of logistics industry can not be separated from the support of a large number of software and hardware in social development. Intelligent Transportation System

The use of advanced science and technology enables managers to obtain detailed data and information about road and vehicle status, and to grasp specific trends at any time and anywhere. Intelligent Transportation System (ITS) mainly collects, processes, publishes, exchanges, analyses and utilizes information to provide comprehensive personalized services for traffic participants.

With the rapid development of Intelligent Transportation System (ITS) and the collaborative communication of logistics fleet in the process of moving, higher accuracy and real-time requirements are put forward for information sharing and transmission. Therefore, vehicular wireless ad hoc networks have received widespread attention. At the same time, the problem of hidden terminals, which can easily cause data loss and seriously affect network throughput, capacity and data transmission delay, has also been studied. To detect hidden data conflicts in time, improve the value of information sharing, reduce unnecessary transport losses, improve transport efficiency and reduce transport costs has become an urgent problem to be solved in China's logistics industry.

In this paper, the characteristics of VANET and the theoretical basis of hidden terminal are introduced in detail, and several situations of hidden terminal in VANET are analyzed concretely. At the same time, the basic principle of lower bitmap analysis is briefly introduced. A data package including bitmap information is added to the daily vehicle CAM broadcasting. By comparing the label bits of the received data package, we can judge whether there are hidden data conflicts in the current communication network. After that, the different situations of different bitmap markers and their specific operation in the process of logistics convoy are introduced in detail. As far as data packets have been received, they can be divided into two categories according to whether communication caches have been generated or not, which provides a new way to recognize and detect hidden terminals.

According to the comparison method of bitmap information, a hidden terminal detection system in the collaborative communication of intelligent logistics fleet is designed by using Visual Basic, which mainly realizes the functions of real-time viewing of communication link state, global state of vehicle node communication, judgment of local hidden terminal and historical data viewing. Practice has proved that bitmap analysis can accurately and effectively detect the existence of hidden terminals in mobile cooperative communication of logistics fleet, reduce the waste of resources, and increase the accuracy and effectiveness of information transmission.

Key words: Hidden terminal; Vehicular wireless ad hoc network; Cooperative communication; Bitmap anal

目 录