毕业论文移动版

摘要无线自组织网络是一系列具有无线通信能力节点组成的局部通信网络，与GSM不同，它不依赖于任何固定的网络基础设备（基站）。网络中的节点可以相互交换信息，如果两个节点彼此不在通信范围内时，可以通过中间节点中继来实现多跳通信。这时，这些中间节点既作为终端又承担路由的功能。由于无线信道是共享信道，多跳中继通信加剧了信道的竞争与冲突，使网络性能下降。66666

IEEE 802.11 DCF（Distributed Control Function）协议是一种用于Ad hoc 网络的无线信道接入协议。802.11 DCF是一种竞争接入协议，退避机制是缓解竞争冲突的一种解决方法。除了退避策略,802.11 DCF在MAC层还采用网络分配矢量NAV（Network Allocation Vector）避免竞争接入产生的冲突。在详细分析802.11 DCF协议后，绘制数据发送和接收的流程图、对802.11协议定义的帧进行了适当简化，仅保留RTS、CTS、ACK三种控制帧传送控制信息，与数据帧传送真正的数据。

本文中对系统的运行环境进行了介绍。TQ2440开发板安装Windows CE 6.0操作系统作为系统的运行环境，使用无线通信模块nRF24L01完成通信。在windows CE系统中，应用程序以打开文件的方式与通信模块的驱动程序进行通信，使用WriteFile和ReadFile发送和接收数据。最终程序实现开发板之间的通信。

毕业论文关键词  无线自组织网络  MAC  802.11

毕业设计说明书（论文）外文摘要

Title Design and Realize the MAC layer protocol

for Ad hoc Network

Abstract

Wireless Ad hoc network is a communication network which consists a group of transceived nodes. Unlikely GSM, it doesn’t depend on any network infrastructure, like base station. The nodes can communicate with each other. When two nodes locating out the range of each other, they can realize multi-hops communication via a series of relayed nodes. These relayed nodes are terminals as well as routers. As shared channel, multi-hops communication promotes the contention and collision, which leads to the descent of the performance of network.

IEEE 802.11 DCF is a kind of media access control protocols for wireless ad hoc network. It is a kind of competitive access protocol, and backoff is a concrete way to resolve contention in wireless ad hoc network. Besides backoff, 802.11 DCF also employ NAV(Network Allocation Vector) to avoid collisions. After a long-time analysis of the protocol, I drawed the flow chart for receiving data and sending data, and simplified the format of the frames. Just some control frames (RTS, CTS and ACK) and data frame are retained, and they are properly simplified as well. 

The run-time environment is also mentioned in the dissertation. TQ2440 with Windows CE 6.0 is the basic environment for the software. It communicates by wireless communication module nRF24L01. In windows CE 6.0, application could use the driver of nRF24L01 just like working on usual files, sending data by WriteFile, receiving data by ReadFile. At last, we make two boards communicate.

Keywords wireless ad hoc network MAC 802.11

目录

1 绪论1

1.1 研究背景及意义1

1.2 主要的工作3

2 无线自组织网络MAC层主要研究的内容3

2.1无线链路通信特点3

2.2隐藏终端问题4

2.3 暴露终端问题6

2.4 接入协议7

2.5 802.11 冲突缓解8

2.5.1物理载波侦听与二进制指数回退8  

2.5.2 虚拟载波侦听8

3平台与接口9

  3.1 运行平台9    

  3.2 接口介绍11

      3.2.1 接口函数11

      3.2.2 事件对象14

4 系统设计15 (责任编辑：qin)