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和设备中，对自主分布式无线自组网的研究变得越来越重要。实现了一个灵活的仿真系统，用于评估这种自治无线网络的性能，以研究其设计所必需的基本问题，如频谱有效的中继方案、路由问题和位置管理。本课题取得的主要研究成果总结如下：1.研究了自组网的频谱效率和终端功率消耗，并与蜂窝系统的频谱效率和终端功耗进行了比较。研究发现，在保证最大同时路由数目的前提下，存在一个最优跳距，且功耗与蜂窝系统相当，并对路由方案进行了改进，使其适用于终端分布不均匀的情况。提出了一种适用于adhoc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估。该算法以基于簇的路由协议(CBRP)为基础，利用位置和速度信息寻找更健壮的路径。提出了一种基于全城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估。移动站试图使用由稀疏分散的简单固定站收集和保存的位置信息来找到其目的地。利用IEEE802实现了一个由笔记本电脑组成的实验多跳网络。11B无线LAN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，空间频率重用提高了总吞吐量。

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.