无线局域网现状研究

烟台南山学院学士论文I无线局域网现状研究摘要：网络是信息化的基础，网络设施的完善和网络技术的进步，对信息网络化起到积极的推动作用。通常,计算机网络的传输介质主要依赖铜缆或光缆，由此构成有线局域网(LAN)，这一组网模式一直沿用至今。随着Internet应用的迅猛发展，以及笔记本电脑、个人数据助理(PDA)等移动智能终端的日益增长,人们对无线局域网(WLAN)的需求也急剧增加。WLAN利用电磁波在空气中发送和接受数据,而无需线缆介质,其数据传输率通常能达到11Mbps。WLAN在很多应用领域具有独特的优势，可提供随时随地、自由高速接入Internet，让广大用户享受到更多便利、安全的网络服务。近年来,全球范围内无线局域网的数量急剧增加,成为网络发展的必然趋势。本文主要以无线局域网的现状为研究对象。首先把无线局域网的发展历程分为四个时代进行了了简要介绍，之后涉及了WLAN的各项技术标准，物理组成和拓扑结构，WLAN的安全技术，当今的市场状况，应用特色和未来发展。其中WLAN的物理组成和拓扑结构是WLAN的核心问题，它决定着WLAN的性能和发展。最后结合对市场调查资料的分析和当前应用的技术和状况，对WLAN的未来发展做了简单的预测和展望。关键词：IEEE802.11，无线接入点，网络拓扑结构，有线等效保密协议，虚拟专用网络，定位服务烟台南山学院学士论文IIStudyofWirelessLocalAreaNetworkStatusObstract：Networkisthebasisofinformatization,Thebetteringofthenetworkfacilitiesandnetworktechnologyplayanactiveroleinpromotinginformationg-based.Generally,thetransmissionmediumofthecomputernetworkreliesmainlyoncopperorfiberopticcable,whichconstituteawiredlocalareanetwork(LAN),andthenetworkmodelarestillinuse.WiththerapiddevelopmentofInternetapplications,aswellasthegrowingmobileintelligentterminalssuchaslaptopcomputers,personaldataassistant(PDA)andsoon,oneforwirelessLAN(WLAN)isalsoasharpincreaseindemand.WLANtakesadvantageofelectromagneticwavesintheairtosendandreceivedatawithouttheneedforcablemedium,thedatatransferratecanusuallyreachto11Mbps.WLANhasauniqueadvantiagesinmanyapplicationsareathatcanprovideanytime,anywhere,freehigh-speedaccesstoInternet,allowinguserstoenjoymoreconvenience,securityofnetworkservices.Inrecentyears,theincreasingdramaticallyoftheglobalnumberofwirelesslocalareanetworkbecomeaninevitabletrendofnetworkdevelopment.Inthepaper,itismainlyonthestatusofwirelessLANforthestudyobject..Firstofall,thecourseofdevelopmentofwirelesslocalareanetworkisdividedintofouragehadabriefintroduction.SencondlyitisinvolvedineachtechnicalstandardsWLAN,thephysicalcompositionandnetworktopology,WLANsecuritytechnology,today'smarketconditions,theapplicationcharacteristicsandfuturedevelopment.AndthephysicalcompositionandthenetworktopologyarethecoreissueofWLAN,andtheydeterminetheperformanceofWLANanddevelopment.Finally,basedonthemarketsurveydataanalysisandtheapplicationoftechnologyandthecurrentsituation,itmakesasimpleforecastandoutlookinthefuturedevelopmentoftheWLAN.KeyWords:IEEE802.11,WirelessAccessPoint,NetworkTopology,WiredEquivalentPrivacy,VisualPersonalNet,LocationBasedService烟台南山学院学士论文III目录1绪论···················································································11．1引言···············································································11．2概述···············································································12无线局域网的历史背景···························································22．1无线局域网的产生·····························································22．2无线局域网的发展·····························································23无线局域网的组成及拓扑结构··················································53．1WLAN的物理组成·····························································53．2无线局域网的拓扑结构·······················································63．2．1分布对等式拓扑（IBSS）···········································63．2．2基础结构集中式拓扑（BSS）······································73．2．3ESS网络拓扑···························································83．2．4中继（Relay）或桥接（Bridging）型网络拓扑·················94无线网络安全·····································································104．1WLAN的访问控制技术····················································104．2WLAN的数据加密技术·····················································115市场状况···········································································155．1全球市场的发展和竞争·····················································155．2中国的市场状况······························································16烟台南山学院学士论文IV6应用前景和未来发展····························································196．1应用特色·······································································196．2未来发展·······································································207结论·················································································21参考文献·············································································22致谢···················································································23烟台南山学院学士论文11绪论1．1引言信息技术的飞速发展，使得人们对网络通信的需求也随之不断提高，希望打破不同的地域或客观条件的制约，能够实现任何人在任何时候的任何地方于任何人进行任何方式的通信的目标。作为个人通信的一个重要的组成部分，无线局域网已经掀起了移动计算的新浪潮，在现实及未来的社会生活将得到广泛的应用。1．2概述无线局域网络(WirelessLocalAreaNetworks，WLAN)在局域网区域内以无线媒体或介质、利用射频(RadioFrequency，RF)的技术，取代旧式碍手碍脚的双绞铜线(Coaxial)所构成的局域网络，使得无线局域网络能利用简单的存取架构让用户透过它，达到“信息随身化、便利走天下”的理想境界。自从1977年第1个民用局域网系统ARCnet投入运行以来，局域网以其广泛的适用性和技术价格方面的优势，获得了成功和迅速的发展，已成为数据网络领域中基于宿主机的最流行的网络连接形式。进入90年代以来，随着个人数据通信的发展，功能强大的便携式数据终端以及多媒体终端的广泛应用，为了实现任何人在任何时间、任何地点均能实现数据通信的目标，要求传统的计算机网络由有线向无线，由固定向移动，由单一业务向多媒体发展，更进一步推动了WLAN的发展。烟台南山学院学士论文22无线局域网的历史背景无线局域网主要是无线计算机通信网络。无线局域网的历史，也就是无线计算机网络通信的历史。无线通信的历史非常悠久，但无限计算机通信的历史并不长，其优越性是近十几年才发挥出来。2．1无线局域网的产生最早出现的无线局域网可认为是夏威夷大学于1971年开发出的、基于封包式技术的AlohaNet，它采用无线电台替代电缆线的原因是为了克服由于地理环境因素而造成的布线困难。夏威夷群岛由包括Oahu，Maui，Hawaii等在内的几个岛屿组成。夏威夷大学共有10个校地，主校地位于Oahu岛，其他校地分别散布在不同的岛