电气通信 外文翻译 外文文献 英文文献 Wi-Fi的应用及其发展

电气通信 外文翻译 外文文献 英文文献 Wi-Fi的应用及其发展 外文资料翻译译文之二 Wi-Fi的应用及其发展 1 WI-FI组建 方法 快递客服问题件处理详细方法山木方法pdf计算方法pdf华与华方法下载八字理论方法下载 一般架设无线网络的基本配备就是无线网卡及一台AP，如此便能以无线的模式，配合既有的有线架构来分享网络资源，架设费用和复杂程度远远低于传统的有线网络。如果只是几台电脑的对等网，也可不要AP，只需要每台电脑配备无线网卡。AP为AccessPoint简称，一般翻译为“无线访问节点”，或“桥接器”。它主要在媒体存取控制层MAC中扮演无线工作站及有线局域网络的桥梁。有了AP，就像一般有线网络的Hub一般，无线工作站可以快速且轻易地与网络相连。特别是对于宽带的使用，Wi-Fi更显优势，有线宽带网络(ADSL、小区LAN等)到户后，连接到一个AP，然后在电脑中安装一块无线网卡即可。普通的家庭有一个AP已经足够，甚至用户的邻里得到授权后，则无需增加端口，也能以共享的方式上网。 2 WI-FI未来发展 这两年内，无线AP的数量呈迅猛的增长，无线网络的方便与高效使其能够得到迅速的普及。除了在目前的一些公共地方有AP之外，国外已经有先例以无线 标准 excel标准偏差excel标准偏差函数exl标准差函数国标检验抽样标准表免费下载红头文件格式标准下载 来建设城域网，因此，Wi-Fi的无线地位将会日益牢固。 Wi-Fi是目前无线接入的主流标准，但是，Wi-Fi会走多远呢,在Intel的强力支持下，Wi-Fi已经有了接班人。它就是全面兼容现有Wi-Fi的WiMAX，对比于Wi-Fi的802.11X标准，WiMAX就是802.16x。与前者相比，WiMAX具有更远的传输距离、更宽的频段选择以及更高的接入速度等等，预计会在未来几年间成为无线网络的一个主流标准，Intel计划将来采用该标准来建设无线广域网络。这相比于现时的无线局域网或城域网，是质的变革，而且现有设备仍能得到支持，保护人们的每一分钱投资。 总而言之，家庭和小型办公网络用户对移动连接的需求是无线局域网市场增长的动力，虽然到目前为止，美国、日本等发达国家仍然是目前Wi-Fi用户最多的地区，但随着电子商务和移动办公的进一步普及，廉价的Wi-Fi，必将成为那些随时需要进行网络连接用户的必然之选。 最近，业界纷纷传出WI-FI已出现生存危机的消息。据国外媒体报道，日前很多企业仍然在WI-FI这方面投入巨资，但从中赢利的企业几乎没有。据悉很多企业因WI-FI而破产，前不久R Wireless公司也放弃了该项业务。那么WI-FI的盈利情况是否真的出现危机了, 不可否认，WI-FI技术的商用目前碰到了许多困难。一方面是受制于WI-FI技术自身的限制，比如其漫游性、安全性和如何计费等都还没有得到妥善的解决。另一方面，由于WI-FI的赢利模式不明确，如果将WI-FI作为单一网络来经营，商业用户的不足会使网络建设的投资收益比较低，因此也影响了电信运营商的积极性。但从WI-FI技术定位看，我认为，对于电信运营商而言，WI-FI技术的定 位主要是作为高速有线接入技术的补充，将来逐渐也会成为蜂窝移动通信的补充。 虽然WI-FI技术的商用在目前碰到了一些困难，但这种先进的技术也不可能包办所有功能的通信系统。可以说只有各种接入手段相互补充使用才能带来经济性、可靠性和有效性。因而，它可以在特定的区域和范围内发挥对3G的重要补充作用，WI-FI技术与3G技术相结合将具有广阔的发展前景。 3 Wi-Fi二代标准 据国外媒体报道，下一代Wi-Fi标准802.11n的两大主要阵营日前决定摒弃前嫌，共同向美国电气电子工程师学会(IEEE)提交一份统一标准提案。 两大阵营TGn Sync和WWiSE，以及第三方组织MITMOT上月底表示，它们将整合各自的提案，形成一个统一的草案后于今年九月提交IEEE。最终的版本将于今年11月提交。下一代Wi-Fi网络的传输速率可以达到540Mbps，而TGn Sync和WWiSE是这一新标准最强有力的竞争者。过去近一年的时间里，TGn Sync和WWiSE一直坚持各自的802.11n标准，而且都获得了无线厂商的强力支持。 WWiSE获得了德州仪器、Broadcom、 Conexant、 STMicro、 Airgo和Bermai的支持，而此前曾提交自有标准的摩托罗拉也加入了这一阵营;TGn Sync的支持者则包括英特尔、Atheros、Agere、英飞凌、思科、高通、北电网络、三菱、索尼、松下、飞利浦、三星、三洋和东芝。 今年3月，TGn Sync阵营在IEEE工作组的投票中取得领先，但并没有获得足以使WWiSE出局的多数票。随后在5月份的一次投票中，TGn Sync仍然没有建立起明显的优势。为了不至于使802.11n标准的制定陷入僵局，TGn Sync和WWiSE均意识到合作比对抗更有意义。事实上，TGn Sync和WWiSE的标准提案差异并不大，如果两大阵营下月能提交联合标准草案，这一标准几乎肯定会被IEEE 802.11n工作组批准。如果一切顺利，IEEE 802.11n工作组将于明年1月通过802.11n标准。 4 高速有线接入技术的补充 目前，有线接入技术主要包括以太网、xDSL等。WI-FI技术作为高速有线接入技术的补充，具有为可移动性、价格低廉的优点，WI-FI技术广泛应用于有线接入需无线延伸的领域，如临时会场等。由于数据速率、覆盖范围和可靠性的差异，WI-FI技术在宽带应用上将作为高速有线接入技术的补充。而关键技术无疑决定着WI-FI的补充力度。现在OFDM、MIMO(多入多出)、智能天线和软件无线电等，都开始应用到无线局域网中以提升WI-FI性能，比如说802.11n计划采用MIMO与OFDM相结合，使数据速率成倍提高。另外，天线及传输技术的改进使得无线局域网的传输距离大大增加，可以达到几公里。 5 蜂窝移动通信的补充 WI-FI技术的次要定位——蜂窝移动通信的补充。蜂窝移动通信可以提供广覆盖、高移动性和中低等数据传输速率，它可以利用WI-FI高速数据传输的特点弥补自己数据传输速率受限的不足。而WI-FI不仅可利用蜂窝移动通信网络完善的鉴权与计费机制，而且可结合蜂窝移动通信网络广覆盖的特点进行多接入切换 功能。这样就可实现WI-FI与蜂窝移动通信的融合，使蜂窝移动通信的运营锦上添花，进一步扩大其业务量。 Wi-Fi是现有通信系统的补充，可看作是3G的一种补充。 无线接入技术则主要包括IEEE的802(11、802(15、802(16和802(20标准，分别指WLAN、无线个域网WPAN:蓝牙与uwb 、无线城域网WMAN:WIMAX 和宽带移动接入WBMA 等。一般地说WPAN提供超近距离的无线高数据传输速率连接;WMAN提供城域覆盖和高数据传输速率;WBMA提供广覆盖、高移动性和高数据传输速率;WI-FI则可以提供热点覆盖、低移动性和高数据传输速率。 对于电信运营商来说，WI-FI技术的定位主要是作为高速有线接入技术的补充，逐渐也会成为蜂窝移动通信的补充。当然WI-FI与蜂窝移动通信也存在少量竞争。一方面，用于WI-FI的IP话音终端已经进入市场，这对蜂窝移动通信有一部分替代作用。另一方面，随着蜂窝移动通信技术的发展，热点地区的WI-FI公共应用也可能被蜂窝移动通信系统部分取代。但是总的来说，他们是共存的关系，比如一些特殊场合的高速数据传输必须借助于WI-FI，象波音公司提出的飞机内部无线局域网;而在另外一些场合使用WI-FI可以较为经济，象实现高速列车内部的无线局域网时。 此外，从当前WI-FI技术的应用看，其中热点公共接入在运营商的推动下发展较快，但用户数少并缺乏有效的盈利模式，使WI-FI呈现虚热现象。所以，WI-FI虽然是通信业中发展的新亮点，但是主要应定位于现有通信系统的补充。如果炒作过热，面对相对狭小的市场可能出现投资过度和资源闲置的状况。据报道，在美国T-Mobile移动通讯公司经营的遍布2000多家星巴克咖啡厅的“热点”网络，平均每天只有不到两个人使用，而运营商为此每个月就要花费数百美元。 另外目前公共接入服务的应用，除了上网、接收email等既有应用之外，并未出现对使用者而言具有独占性、迫切性、必要性之应用服务，可使消费者产生另一种新的使用需求，这也是它难以大量吸引用户族群的原因。百年来通信发展的历史证明，使用一种包办所有功能的通信系统是不可取的，各种接入手段的混合使用才能带来经济性、可靠性和有效性的同时提高。毫无疑问，第三代蜂窝移动通信(3G)技术是一个比较完美的系统，它有较高的技术先进性、较强的业务能力和广泛的应用。但是WI-FI可以在特定的区域和范围内发挥对3G的重要补充作用，WI-FI技术与3G技术相结合会有广阔的发展前景。 6 WI-FI技术简述 一个Wi-Fi联接点网络成员和结构。 站点，网络最基本的组成部分。 基本服务单元。网络最基本的服务单元。最简单的服务单元可以只由两个站点组成。站点可以动态的联结到基本服务单元中。 分配系统。分配系统用于连接不同的基本服务单元。分配系统使用的媒介逻辑上和基本服务单元使用的媒介是截然分开的，尽管它们物理上可能会是同一个媒介，例如同一个无线频段。 接入点。接入点即有普通站点的身份，又有接入到分配系统的功能。 扩展服务单元。由分配系统和基本服务单元组合而成。这种组合是逻辑上，并非物理上的--不同的基本服务单元物有可能在地理位置相去甚远。分配系统也可以使用各种各样的技术。 关口，也是一个逻辑成分。用于将无线局域网和有线局域网或其它网络联系起来。 这儿有3种媒介，站点使用的无线的媒介，分配系统使用的媒介，以及和无线局域网集成一起的其它局域网使用的媒介。物理上它们可能互相重叠。 IEEE802.11只负责在站点使用的无线的媒介上的寻址。分配系统和其它局域网的寻址不属无线局域网的范围。 IEEE802.11没有具体定义分配系统，只是定义了分配系统应该提供的服务。整个无线局域网定义了9种服务， , 分配，集成, 再联 5种服务属于分配系统的任务，分别为，联接, 结束联接 接。 4种服务属于站点的任务，分别为，鉴权, 结束鉴权, 隐私, MAC数据传输。 Wi-Fi是一种无线传输的 规范 编程规范下载gsp规范下载钢格栅规范下载警徽规范下载建设厅规范下载 ，一般的，带有这个标志的产品表明了你可以利用它们方便地组建一个无线局域网。而无线局域网又有什么好处呢,很明显——无须布线和使用相对自由。 在中国大陆2006年截至,共有商业架设无线热点80000个左右，并有一些网站提供免费和收费的WI-FI无线热点查寻功能 比如:www.Wi-Fi01.com 提供WI-FI无线热点的地图搜索查询功能 。 但是，目前国内对于WI-FI的态度是不予支持的。也就是说国内基本上不推进WI-FI的，尽管现在国内的一些地方还是存在WI-FI网络。 现在的一些移动设备，因为国外在推行WI-FI网络，所以一般都带有WI-FI连接模块。而因为国内的原因，所以一些设备的国内版本就将WI-FI模块去掉了。 7 WI-FI在中国发展——北京 北京无线城市一期建设已经进入尾声，由中电华通负责奥运场馆周边以及市内覆盖建设,主要提供奥运场馆外的游客上网等服务。 北京无线城市建设,有北京市政府大力支持和原信息产业部认可，一期将完成1000个基站的建设。中电华通目前项目已经完成数百个Wi-Fi Mesh和数十个WiMAX基站的布置。 7.1 无线速率可达1Mbps 上海嘉定是我国内地首个由政府签约的无线城市计划，项目建设200,300个Wi-Fi基站。北京的规模更大，共有三期 规划 污水管网监理规划下载职业规划大学生职业规划个人职业规划职业规划论文 涉及全市城乡，无线宽带不提供语音服务，与3G为互补关系。 目前，中关村、金融街、CBD等地区已经有无线宽带的覆盖，用户有Wi-Fi功能的手机或笔记本可以稳定使用1Mbps速率。该网络目前处于调试阶段，并未做宣传推广，中电华通统计,仅在金融街每天的在线人数达1000,2000人. 中电华通力争在奥运前完成环线(二环、三环)的全部覆盖。该公司仍在探索运营和收费模式，完善网络安全设置,未来进入正式运营对个人用户可能会有速率和资费的设定。 7.2 采用WiMAX+Wi-Fi技术 北京的城市地形复杂且圈地竞争激烈,对于中电华通这样的运营商，光纤的铺设成本高昂，而WiMAX可以轻而易举的完成大的区域覆盖，回传数据代替光纤。 由于WiMAX的芯片和笔记本等未能规模商用,因此该技术仅作为骨干传输，而Wi-Fi作为“世界唯一的通用标准”，终端种类多且价格低廉,几乎所有笔记本都支持,，建设基站后可迅速投入商用。中电华通一般将Wi-Fi基站置于路边灯杆，这也是全球无线城市建设中解决站址问题的上佳 方案 气瓶 现场处置方案 .pdf气瓶 现场处置方案 .doc见习基地管理方案.doc关于群访事件的化解方案建筑工地扬尘治理专项方案下载 。 Wi-Fi Mesh是一种新型公共无线局域网和城域网解决方案，其网络结构类似于渔网，从一个点到另一个点有很多路可以走，这样即使有个别站点故障仍然可以保持较好的覆盖。Wi-Fi技术在几年间不断进步，Wi-Fi Mesh的特点是:“自动发现，自动组织，自动均衡，自动修复”。 7.3 无线北京 渐行渐近 春树街道办周围较早建设有Wi-Fi Mesh网，无线宽带除 中电华通在宣武区 了互联网接入，还有智能交通、视频监控等多种应用。 宣武区信息办的网络状态稳定，信号好，居民反馈良好，信息办要求中电华通提供居民上网、数字家园、应急通信三个方面的业务。 在网络建设中，频率问题、环保问题、站址问题等方面面的障碍均基本解决。无线宽带上网期待多年，北京无线城市在一期工程后还等待更大规模的建设。 8 Wi-Fi的认证 目前 Wi-Fi联盟所公布的认证种类有: * WPA/WPA2:WPA/WPA2是基于IEEE 802.11a、802.11b、802.11g的单模、双模或双频的产品所建立的测试程序。内容包含通讯协定的验证、无线网络安全性机制的验证，以及网络传输表现与相容性测试。 * WMM(Wi-Fi MultiMedia):当影音多媒体透过无线网络的传递时，要如何验证其带宽保证的机制是否正常运作在不同的无线网络装置及不同的安全性设定上是WMM测试的目的。 * WMM Power Save:在影音多媒体透过无线网络的传递时，如何透过管理无线网络装置的待命时间来延长电池寿命，并且不影响其功能性，可以透过WMM Power Save的测试来验证。 * WPS(Wi-Fi Protected Setup):这是一个2007年年初才发布的认证，目的是让消费者可以透过更简单的方式来设定无线网络装置，并且保证有一定的安全性。目前WPS允许透过Pin Input Config(PIN)、 Push Button Config(PBC)、USB Flash Drive Config(UFD)以及Near Field Communication Contactless Token Config(NFC)的方式来设定无线网络装置。 * ASD(Application Specific Device):这是针对除了无线网络存取点(Access Point)及站台(Station)之外其他有特殊应用的无线网络装置，例如DVD播放器、投影机、打印机等等。 * CWG(Converged Wireless Group):主要是针对 Wi-Fi mobile converged devices 的 RF 部分测量的测试程序。 外文资料原文之二 Wi-Fi application and its development 1 Wi-Fi networks method General set up wireless network basic is equipped with wireless network card and a AP, so that they can be in a wireless mode, with the existing cable structure to share cyber source, installation cost and complexity is much lower than the traditional wired networks. If only a few computer network, also can not AP, only need to each computer equipped with a wireless network card. AP AccessPoint, generally translated as " wireless access node", or" bridge". It is mainly in the media access control layer MAC plays wireless workstation and wired LAN bridge. With AP, like Hub general cable network, wireless station can be quickly and easily connected with network. Especially for the use of broad band, Wi-Fi has more advantages, wired broadband network ( ADSL, district LAN ) door hind, connected to a AP, then in the computer to install a wireless network card. Ordinary family has a AP is enough, even a user's neighborhood is authorized, without increasing the port, but also able to share the internet. 2 WI-FI development in the future These two years, the number of wireless AP was the rapid growth of wireless network, can make it convenient and efficient fast popularization. Except in some of the current public place has AP, foreign countries have a precedent to wireless standard to the construction of metropolitan area network, therefore, Wi-Fi wireless position will grow strong. Wi-Fi is currently the mainstream standard of wireless access, however, Wi-Fi will go far? In Intel 's strong support, the Wi-Fi has a successor. It is fully compatible with existing Wi-Fi WiMAX, in contrast to the Wi-Fi 802.11X standard, WiMAX is 802.16x. Compared with the former, WiMAX has farther transmission distance, wider frequency band and high access speed and so on, is expected to be in the next few years to become a mainstream wireless network standard, using the standard Intel planning for the future construction of a wireless wide area network. This compared to the current wireless LAN or metropolitan area network, is a qualitative change, and the existing equipment can still be supported, protect people every penny investment. To make a long story short, home and small office network users demand for mobile connectivity wireless LAN market growth, although so far, the United States, Japan and other developed countries is still the current Wi-Fi users most area, but along with the electronic commerce and mobile office for further popularization, cheap Wi-Fi, will become those who always require a network connection the user's inevitable choice. Recently, the industry have been WI-FI has appeared to survive the crisis. According to foreign media coverage, recently many enterprises are still in WI-FI which invested heavily, but almost no profit from business. It is reported a lot of enterprises because of WI-FI bankruptcy, shortly before R Wireless also gave up the business. So WI-FI 's earnings really crisis? Admittedly, WI-FI technology business at present many difficulties. One is subject to WI-FI technical limitations, such as its roaming nature, safety and how accounting have not been properly solved. On the other hand, because of the profit pattern of WI-FI is not clear, if WI-FI as a single network management, business users are insufficient will cause the network construction investment income is relatively low, thus also affected the telecommunication operator enthusiasm. But from the WI-FI positioning technology, I think, for telecom operators, WI-FI technology is mainly as a high-speed cable access techniques complement, gradually will become the future cellular mobile communication complement. Although commercially available in the current WI-FI technology encountered some difficulties, but this advanced technology can not be arranged all the functions of communication system. It can be said that only a variety of access means mutual supplement use can bring economic, reliability and validity. Therefore, it can be in a particular region and range play on important role of complement 3G, WI-FI combined with 3G technique will have wide development prospect. 3 Wi-Fi two standard According to foreign media reports, the next generation of Wi-Fi standard 802.11n two main factions recently decided to put aside their differences, common to the United States Institute of electrical and Electronics Engineers ( IEEE ) submitted a unified standard proposal. Two camps TGn Sync and WWiSE, as well as the third party MITMOT end of said, they will integrate their proposal, form a unified bill submitted in September, IEEE. The final version will be submitted in November. The next generation of Wi-Fi network transmission rate can reach 540Mbps, while TGn Sync and WWiSE is one of the most powerful competitor new standard. Last year, TGn Sync and WWiSE has always adhered to the respective 802.11n standard, and have obtained the wireless manufacturers strong support. WWiSE won the Dezhou instrument, Broadcom, Conexant, STMicro, Airgo and Bermai support, previously submitted its own standard Motorola joined the camp; TGn Sync supporters include Intel, Atheros, Agere, Infineon, Cisco, Nortel Networks, high-pass, Mitsubishi, Sony, Panasonic, Philips, Samsung, Sanyo and toshiba. In March this year, the TGn Sync camp in IEEE working group of the vote in the lead, but did not get sufficient to enable the WWiSE out of the majority of votes. Then in May a vote, TGn Sync still did not establish clear advantage. So as not to make 802.11n standards come to a deadlock, TGn Sync and WWiSE were aware of cooperation more meaningful than confrontation. In fact, TGn Sync and WWiSE proposed standard difference is not big, if two camps next month to submit joint draft standard, this standard will almost certainly be approved IEEE 802.11n working group. If all goes well, the IEEE 802.11n working group will be in January next year by 802.11n standard. 4 High speed cable access technology supplement At present, the cable access techniques mainly include Ethernet, xDSL etc.. The WI-FI technology as a high-speed cable access technology supplement, with mobility, low price advantages, WI-FI technology is widely used in cable access wireless extension of fields, such as a temporary venue. Because the data rate, coverage and reliability of difference, WI-FI technology in broadband application will function as a high speed cable access technology supplement. And the key technology is deciding the WI-FI added strength. Now OFDM, MIMO ( MIMO ), smart antenna and software radio, are applied to the wireless local area network in order to improve WI-FI performance, for example 802.11n program using MIMO combined with OFDM, so that the data rate is doubled. In addition, antenna and transmission technology the improvement makes the wireless LAN transmission distance increases greatly, can reach several kilometers. 5 Cellular mobile communication complement WI-FI technology -- secondary localization of cellular mobile communication complement. Cellular mobile communication can provide wide coverage, high mobility and low data transmission rate, it can use WI-FI high speed data transmission characteristics to make up for their lack of data transmission rate limited. WI-FI not only can make use of cellular mobile communication network to improve the authentication and accounting mechanisms, but also can be combined with cellular mobile communication network coverage features are multiple access switching function. This can be achieved WI-FI and cellular mobile communication integration, so that the cellular mobile communication operation the icing on the cake, to further expand its operations. Wi-Fi is the existing communication system supplement, can be seen as a complement to 3G. Wireless access technology including IEEE 802.11, 802.15, 802.16 and 802.20, respectively, WLAN WPAN WPAN: UWB, Bluetooth and wireless metropolitan area network and WMAN: WIMAX and broadband mobile access and WBMA. Generally WPAN provides super close distance wireless high rate data transmission connection; WMAN metropolitan area coverage and high data transmission rate; WBMA provides wide coverage, high mobility and high data transmission rate; WI-FI can provide hot spot coverage, low mobility and high data transmission rate. For telecom operators, WI-FI technology is mainly as a high-speed cable access techniques complement, gradually will also become the complement of cellular mobile communication. Of course, WI-FI and cellular mobile communication is the presence of a small amount of competition. On one hand, used for WI-FI IP voice terminal has entered the market, the mobile communication has a partial substitution effect. On the other hand, along with the cellular mobile communication technology development, hot spots of WI-FI common application may also be a cellular mobile communication system to replace part of. But in general, they are coexistence, such as some special occasions of high speed data transmission by WI-FI, like Boeing proposed aircraft internal wireless local area network; and in some other occasions to use WI-FI can be more economic, as high speed trains within wireless lan. In addition, from the current application of WI-FI technology, which focuses on public access operators under the impetus of development is rapidder, but the user quantity and the lack of an effective profit models, to make WI-FI show virtual thermal phenomena. So, although WI-FI is in communication industry new development, but should be mainly located in the existing communication system complement. If overheated speculation, in the face of relatively narrow market may lead to overinvestment and resources idle condition. According to the report, in the United States T-Mobile mobile communications company to operate throughout the more than 2000 Starbucks cafe "hot spots" network, a daily average of less than two individuals, and a carrier therefor it can cost hundreds of dollars each month. In addition the public access service application, in addition to the Internet, receives the email is applied, did not appear to the user has exclusive sex, pressing sex, necessity of application service, can make consumer generates another new needs, it is difficult to attract large number of user groups causes. Hundred years of communication development history has proved, using a arranged all the features of the communication system is not desirable, various means of access of mixed use can bring economic, reliability and validity of the improved at the same time. No doubt, the third generation mobile communication ( 3G ) technique is a relatively perfect system, it has high advanced technology, strong operational capacity and wide application. But WI-FI can be in a particular region and range play on important role of complement 3G, WI-FI combined with 3G technique will have wide development prospect. 6 WI-FI technology introduction A Wi-Fi connection network members and structures The site ( Station ), the network is the most basic component. The basic service unit ( the Basic Service Set, BSS ). Network basic service unit. The most simple service unit only from two sites. The site can be dynamically linked ( Associate ) to the basic service unit. Distribution system ( Distribution System, DS ). Distribution system for connecting the different basic service unit. Distribution system using the medium ( Medium ) logic and basic service unit using the medium is completely separate, although they may be physical with a medium, such as a radio frequency band. Access point ( Acess Point, AP ). The access point is a common site of identity, and access to the distribution function of the system. Extended services unit ( Extended Service Set, ESS ). The distribution system and the basic service unit assembly. This combination is logical, not physically different basic service unit for possible in the location far away from the. Distribution system can also use a variety of techniques. Gateway ( Portal ), is also a logical components. For wireless local area network and the wired local area network or other network linking. There are 3 kinds of media, the site using the wireless medium, distribution system using the media, as well as the wireless local area network and integrated with other local area network using the medium. Physically they may overlap each other. IEEE802.11 is only responsible for the site using the wireless medium . The address ( Addressing ). Distribution system and other local area network address does not belong to the range of wireless local area network. IEEE802.11 has no specific definition of distribution system, but defines a distribution system should provide services ( Service ). The wireless local area network WLAN defines 9 kinds of services, 5 service belongs to the distribution system tasks, respectively, coupling (Association ), end connection (Diassociation), distribution ( Distribution ), integration ( Integration ), coupled with ( Reassociation ). 4 service belongs to the site tasks, respectively, authentication ( Authentication ), end authentication (Deauthentication), privacy ( Privacy ), MAC data transmission ( MSDU delivery ). Wi-Fi is a wireless transmission to the specification, in general, with the logo on the products that you can use them to easily set up a wireless lan. But the wireless local area network and what benefits? Obviously -- without wiring and using the relative freedom. In mainland China ended in 2006, a total of business set up wireless hotspot about 80000, and there are a number of websites offering free and charge WI-FI wireless search function For example: www.Wi-Fi01.com WI-FI wireless hotspot map search query function. However, currently the WI-FI attitude is not supported. That is to say the domestic basically don't push WI-FI, although is now home to some place or the presence of WI-FI network. Now the number of mobile devices, because foreign in the implementation of WI-FI network, so in general with a WI-FI connection module. But because domestic reasons, so some equipment for the domestic version will be WI-FI module removed. 7 WI-FI development in China -- Beijing Wireless Beijing city the first phase of construction has entered the stage, by the CLP for Olympic venues surrounding and inner-city cover construction, provide the main Olympic venues and foreign tourists Internet services. Beijing wireless city construction, Beijing City Hall support energetically and the former Ministry of information industry recognition, a period will be completed in 1000 the construction of base stations. CLP, the project has completed hundreds of Wi-Fi Mesh and dozens of WiMAX station layout. 7.1 Wireless speed can reach 1Mbps Shanghai Jiading is China's first by the government signed the wireless city plan, project 200 to 300 Wi-Fi base station. Beijing is larger, a total of three involved in the city's urban and rural planning, wireless broadband does not provide the voice service, and 3G as a complementary relationship. At present, Zhongguancun, Financial Street, CBD and other regions have wireless broadband coverage, users have Wi-Fi function of the mobile phone or laptop can be stabilized using 1Mbps rate. The network is currently in the testing phase, did not make the promotion, CLP, statistics, only in the Financial Street daily online number amounts to 1000 ~ 2000 people. CLP, strive to complete the link before the Olympic Games ( men, Sanhuan) full coverage. The company is still in the exploratory operation and charging mode, perfect network security settings, coming into the formal operation of individual users may rate and price setting. 7.2 Using WiMAX+Wi-Fi Technology Beijing city complex terrain and the fierce competition, the CLP, such operators, optical fiber laying cost is high; and WiMAX can be an easy job to completion of large area coverage, return data instead of optical fiber. Because the WiMAX chip and the notebook to scale commercial, so the technique is only used as a backbone transmission; and Wi-Fi as "the world's only standard", the terminal variety and low prices, almost all notebook support, construction of base station can be rapidly launch business. CLP, general Wi-Fi base station in the road lamp pole, which is global wireless city construction to solve the problem the best scheme of site. Wi-Fi Mesh is a new type of public wireless local area network and metropolitan area network solution, its network structure is similar to a fishing net, from one point to another point there are many paths, so that even if the individual site failure can still maintain good coverage . Wi-Fi technology in several years of continuous progress, the characteristic is: Wi-Fi Mesh" automatic discovery, automatic, automatic balancing, auto repair". 7.3 Wireless Beijing Jianxingjianjin CLP, in Xuanwu District Street office building now around earlier Wi-Fi Mesh network, wireless broadband Internet access and in addition, intelligent traffic, video surveillance and other applications. Xuanwu District information office network state stability, signal is good, residential good feedback, information office CLP provides residents Internet access, digital home, emergency communication in three aspects of the business. In the network construction, frequency, environmental issues, such as aspects of the disorder are location problem is solved basically. Wireless broadband Internet look years, Beijing wireless city in the first phase of the project is awaiting more large-scale construction. 8 Wi-Fi certification The Wi-Fi Alliance announced certification types: * WPA / WPA2: WPA / WPA2 is based on IEEE 802.11a, 802.11b, 802.11g mode, dual or dual-frequency products established by testing program. Content includes protocol validation, wireless network security mechanisms of authentication, and the network transmission performance and compatibility test. * WMM ( Wi-Fi MultiMedia ): when the audio and video multimedia wireless network transmission, to verify its bandwidth guaranteed mechanism whether normal operation in different wireless network device and different security settings on the WMM test purpose. * WMM Power Save: in multimedia wireless network transmission, how to manage a wireless network device of standby time to extend battery life, and does not affect the functionality, can be through the WMM Power Save testing to verify. * WPS ( Wi-Fi Protected Setup ): This is a 2007 the beginning of the year to release the certification, the purpose is to let consumer can use simpler way to set up a wireless network device, and ensure a certain degree of safety. The current through the Pin Input WPS allows Config (PIN), Push Button Config ( PBC ), USB Flash Drive Config ( UFD ) and Near Field Communication Contactless Token Config ( NFC ) way to set the wireless network device. * ASD ( Application Specific Device ): This is the wireless network access points ( except Access Point ) platform ( Station ) and other special applications of the wireless network device, such as a DVD player, projector, printer etc.. * CWG ( Converged Wireless Group ): Wi-Fi mobile converged devices is mainly directed against the RF component measurement test procedure.