Ad Hoc Network英文简介.ppt

Ad Hoc Network 1、INTRODUCTION The mobile communication network we often mention generally has a center. It is running based on the pre-established network facilities 。 We know that the communication range of the satellite communication system is the most widely used to provide communication services for users in every corner of the world. In this system, satellite plays a similar function with the base station. But the cost of satellite communications system is high, the propagation delay（传输延时） is long and the bandwidth is limited。 The mobile communication system requires the support of the wired network communications infrastructure(基础设施), such as base stations, switches, satellites. The establishment and operation of these facilities require a lot of manpower and material resources, so the cost is relatively high,and the building needs a long time. The Ad Hoc network hosts network by itself without base stations, therefore, the network has a low cost, while the time is short, it is only a few seconds or minutes. Ad Hoc network is a Multi-hop, no center, self-organizing wireless network，also known as Multi-hop Network（多跳网 ） Infrastructureless Network（无基础设施网 ） Self-organizing Network（自组织网） For home wireless Local Area Network setting up, I think we all know the most simple that two computers with wireless network card complete wireless interconnection. One of the computers connected to the Internet can share the bandwidth. As shown, a structure is completed to form based on Ad Hoc WLAN。 No fixed infrastructure in the entire Ad Hoc network, each node is mobile and can be in any way to maintain contact with other nodes. In this network, owing to the limited nature of the end wireless coverage range，two user terminals(终端) that can not directly communicate can make use of other nodes for packet forwarding. Each node is also a router, they are able to complete discovery and to maintain the function to the other