Early Microwave Tower Microwaves were first used to transmit across long distances that were difficult to wire as long as line-of-sight was possible. This tower was installed in 1969 in Boulder Junction, Colorado. (Image courtesy of AT&T.)

wireless LAN

A local area network that transmits over the air typically in an unlicensed frequency such as the 2.4GHz band. A wireless LAN does not require lining up devices for line of sight transmission like IrDA. Wireless access points (base stations) are connected to an Ethernet hub or server and transmit a radio frequency over an area of several hundred to a thousand feet which can penetrate walls and other non-metal barriers. Roaming users can be handed off from one access point to another like a cellular phone system. Laptops use wireless modems that plug into an existing Ethernet port or that are self contained on PC cards, while stand-alone desktops and servers use plug-in cards (ISA, PCI, etc.).

There have been numerous proprietary products on the market for home and office, but Proxim\’s OpenAir and the IEEE 802.11 are two major standards for which numerous products are available. Bluetooth and HomeRF are home and small office technologies that are expected to proliferate in the 2000-2002 time frame. Such systems have a more limited range and do not support roaming. Small wireless LANs are sometimes called “personal area networks” (PANs) since one of their primary uses is to serve an individual connecting a laptop or PDA to a desktop machine. See 802.11, WPAN, Bluetooth, HomeRF, HIPERLAN and IrDA.

Wireless LAN Wireless LANs function like cellphone systems. Each access point is a base station that transmits over a radius of several hundred feet. In systems designed for office use, users can seamlessly roam between access points without dropping the connection.

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