 History Wi-Fi was created in 1991 by NCR Corporation/ AT&T (later Lucent & Agere Systems) in Nieuwegein, the Netherlands. It was initially intended for cashier stations; the first wireless products were brought on the market under the name WaveLAN with speeds of 1 Mb to 2 Mb. Vic Hayes, who was the primary inventor of Wi-Fi and has been named the “Father of Wi-Fi,” was involved in designing standards such as IEEE 802.11b, 802.11a and 802.11g standards. In 2003, Vic retired from Agere Systems. Agere’s 802.11a/b/g all-in-one chipset (code named: WARP) never made it to market, and Agere Systems decided to quit the Wi-Fi market in late 2004. Origin and meaning of the term “Wi-Fi” Despite the similarity between the terms “Wi-Fi” and “Hi-Fi,” statements reportedly made by Phil Belanger of the Wi-Fi Alliance contradict the popular conclusion that “Wi-Fi” stands for “Wireless Fidelity.” According to Mr. Belanger, the Interbrand Corporation developed the brand “Wi-Fi” for the Wi-Fi Alliance to use to describe WLAN products that are based on the IEEE 802.11 standards. In Mr. Belanger’s words, “Wi-Fi and the yin yang style logo were invented by Interbrand. We (the founding members of the Wireless Ethernet Compatibility Alliance, now called the Wi-Fi Alliance) hired Interbrand to come up with the name and logo that we could use for our interoperability seal and marketing efforts. We needed something that was a little catchier than IEEE 802.11b Direct Sequence.” The Wi-Fi Alliance themselves invoked the term “Wireless Fidelity” with the marketing of a tag line, “The Standard for Wireless Fidelity,” but later removed the tag from their marketing. The Wi-Fi Alliance now seems to discourage propagation of the notion that
Wi-Fi: How it works The typical Wi-Fi setup contains one or more Access Points (APs) and one or more clients. An AP broadcasts its SSID (Service Set Identifier, “Network name”) via packets that are called beacons, which are broadcast every 100 ms. The beacons are transmitted at 1 Mb, and are of relatively short duration and therefore do not have a significant influence on performance. Since 1 Mb is the lowest rate of Wi-Fi it assures that the client who receives the beacon can communicate at least 1 Mb. Based on the settings (e.g. the SSID), the client may decide whether to connect to an AP. Also the firmware running on the client Wi-Fi card is of influence. The Wi-Fi standard leaves connection criteria and roaming totally open to the client. This is a strength of Wi-Fi, but also means that one wireless adapter may perform substantially better than the other. Since Wi-Fi transmits in the air, it has the same properties as a non-switched Ethernet network. Even collisions can therefore appear like in non-switched Ethernet LAN’s. Channels Except for 802.11a, which operates at 5 GHz, Wi-Fi uses the spectrum near 2.4 GHz, which standardized and unlicensed by international agreement, although the exact frequency allocations vary slightly in different parts of the world, as does maximum permitted power. However, channel numbers are standardized by frequency throughout the world, so authorized frequencies can be identified by channel members. With the required spacers, only 3 channels (1,6 and 11) can be used simultaneously without interference.
Wireless Access Point (WAP) A wireless access point (AP) connects a group of wireless stations to an adjacent wired local area network (LAN). An access point is similar to an Ethernet hub, but instead of relaying LAN data only to other LAN stations, an access point can relay wireless data to all other compatible wireless devises to communicate with any other device on the LAN. Wireless Routers A wireless router integrates a wireless access point with an Ethernet switch and an Ethernet router. The integrated switch connects the integrated access point and the integrated Ethernet router internally, and allows for external wired Ethernet LAN devices to be connected as well as a (usually) single WAN device such as a cable modem or DSL modem. A wireless router advantageously allows all three devices (mainly the access point and router) to be configured through one central configuration utility, usually through an integrated web server. However one disadvantage is that one may not decouple the access point so that it may be used elsewhere. Wireless Ethernet Bridge A wireless Ethernet bridge connects a wired network to a wireless network. This is different from an access point in the sense that an access point connects wireless devices to a wired network at the data-link layer. Two wireless bridges may be used to connect two wired networks over a wireless link, useful in situations where a wired connection may be unavailable, such as between two separate homes. Range Extender A wireless range extender (or wireless repeater) can increase the range of an existing wireless network by being strategically placed in locations where a wireless signal is sufficiently strong and near by locations that have poor to no signal strength. Advantages of Wi-Fi Allows LAN’s to be deployed without cabling, typically reducing the costs of network deployment and expansion. Spaces where cables cannot be run, such as outdoor areas and historical buildings, can host wireless LAN’s. Wi-Fi products are widely available in the market. Different brands of access points and client network interfaces areinteroperable at a basic level of service. Products designated as Wi-Fi CERTIFIED by the Wi-Fi Alliance are interoperable. Wi-Fi networks support roaming, in which a mobile client station such as a laptop computer can move from one access point to another as the user moves around a building or area.Wi-Fi is a global set of standards. Unlike cellular carriers, the same Wi-Fi client works in different countries around the world. Widely available in more than 250,000 public hot spots and millions of homes and corporate and university campuses worldwide. Commercial Wi-Fi Commercial Wi-Fi services are available in places such as Internet cafes, coffee houses, hotels and airports around the world (commonly called Wi-Fi cafes). In the U.S.:
Taken from Wikipedia, The Free Encyclopedia, at http://en.wikipedia.org/wiki/WiFi and http://en.wikipedia.org/wiki/Wireless_mesh_network
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