Simulation System for Performance Evaluation of Autonomous Distributed Wireless Ad Hoc Information Networks

随着大量无线收发芯片嵌入到日常生活中的每一个设备中，研究一种自主分布的无线自组织网络变得越来越重要。为了研究自主无线网络设计中不可缺少的频谱效率中继方案、路由问题和位置管理等基本问题，设计了一套灵活的自主无线网络性能评估仿真系统。通过该项目获得的主要研究成果总结如下：1。研究了自组织网络的频谱效率和终端功耗，并与蜂窝网络进行了比较。我们发现存在一个最优跳距保证最大数量的同时路由，并且功耗与蜂窝系统相当。修改了路由方案，使其适用于终端分布不均匀的情况。提出了一种用于自组织网络的分层路由协议，并通过计算机仿真对其性能进行了评价。它基于CBRP（基于集群的路由协议），利用位置和速度信息找到更健壮的路由。提出了一种基于城市范围无线多跳网络的目的地发现方案，并通过计算机仿真对其性能进行了评价。移动电台试图利用位置信息找到它的目的地，而位置信息是由分散的简单的固定电台收集和保存的。采用IEEE802实现了一个由笔记本电脑组成的实验性多跳网络。对11b无线局域网卡及其吞吐量进行了评估。通过降低发射机功率和引入多跳连接，由于空间频率复用，总吞吐量增加。

With a recent trend to embed huge number of wireless transceiver chips to every device and equipment in daily life, study of an autonomous distributed wireless ad hoc networking is getting more and more important. A flexible simulation system for the performance evaluation of such autonomous wireless networks has been implemented to study fundamental problems indispensable for its design, such as spectrally efficient relaying scheme, routing issue and location management. Major research results obtained through the project are summarized below.1. Spectral efficiency and terminal power consumption of ad hoc networks were studied and compared with those of cellular system. We found that an optimum hop distance exists assuring the maximum number of simultaneous routes, and power consumption is comparable to the cellular system.Routing scheme is modified so that it is applicable to the non-uniform terminal distribution case.2. A hierarchical routing protocol for ad hoc networks has been proposed and its performance has been evaluated by computer simulations. It is based on CBRP (Cluster Based Routing Protocol) and finds more robust routes by utilizing location and velocity information.3. A destination discovery scheme has been proposed assuming a city-wide wireless multi-hop network and its performance has been evaluated by computer simulations. A mobile station tries to find its destination using the location information, which is collected and kept by sparsely scattered simple fixed stations.4. An experimental multi-hop network consisting of notebook PC's is implemented using IEEE802. 11b wireless LAN cards and its throughput is evaluated. By reducing the transmitter power and introducing multi-hop connection, total throughput is found to increase owing to the spatial frequency reuse.