The Wlan

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A wireless LAN or WLAN is a wireless local area network, which is the linking of two or more computers without using wires. It is the same as LAN, but has a wireless interface. WLAN utilizes spread-spectrum technology based on radio waves to enable communication between devices in a limited area, also known as the basic service set. This gives users the mobility to move around within a broad coverage area and still be connected to the network. Wireless Local Area networks (WLANs) have been employed to add mobility features to office and campus networks since the late 1980s. This article presents a discussion of the current state of WLAN technology and some of the products available. Physically, there are two ways to implement wireless LANs: infrared and radio. Since radio is currently the most popular choice, we will restrict this discussion to radio wireless LANs. WLANs are a distinct category of products and technology that must be differentiated from Metropolitan Area Networks (MANs) and Wide Area Networks (WANs). Examples of wireless MANs are Ricochet, Ardis, and RAM Mobile Data which provide city-wide coverage for low bit-rate data services. The most visible wireless WAN system is the cellular telephone system which can be used for data services just as telephone land lines can be used with a modem for data services. However, the bandwidth limitations when using switched cellular technology are severe, and data connections generally are not tolerant of the extended drop-outs that can occur. Conversely, WLANs are generally accepted to be 1Mbps links or above (although a few drop into the 100's of Kbps), short range (100's of meters) technologies which do not need to support vehicular mobility (high speed handoffs) or wide area coverage. What they do provide is the wireless equivalent of a LAN for file sharing, remote database access, file server access, internet access, e-mail, and all the other applications which operate over LANs, only the user is no longer tethered to an RJ45 wall jack. Note also that there are a few applications of WLAN technology which operate over great distances (1-20 miles) but they are not generally regarded as WLANs, but as wireless bridges or point-to-point data links. This technology is becoming more and more popular, especially with the rapid emergence of small portable devices such as PDAs (personal digital assistants).

The notebook is connected to the wireless access point using a PCMCIA wireless card.

54 MBit WLAN PCI Card (802.11g)
WLAN, (Wireless Local Area Network), is a high-speed wireless technology for accessing the Internet or corporate intranet. Two or more WLAN-enabled devices such as Nokia 9500 Communicators or WLAN-enabled laptops can also make an independent connection between each other. The Wi-Fi Alliance has developed specifications for three common WLAN implementations - 802.11b, 802.11g, and 802.11a. Most WLAN networks today are based on these three standards. As a result, WiFi and WLAN are almost interchangeable terms. HISTORY

WLAN products were initially developed to support vertical market applications, i.e. sold as components of a specific solution to a specific problem where user and station mobility were required. You may be familiar with one or more of the following WLAN vertical applications: •Hertz rental car portable check-in terminals,

Wal-Mart inventory and pricing terminals, and
Hospital portable patient information terminals.
In each of these applications, the WLAN was deployed to support the specific application. The WLAN was not a part of the general purpose LAN infrastructure. More recently, particularly because of recent steps towards WLAN standardization, WLANs are being deployed to support general purpose LANs. IEEE 802.11 - A standard is born

Until the summer of 1997, there were no standards for wireless LAN products. Each vendor defined the protocols and signaling for their own products, and these proprietary products...
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