Wireless LANs

The booming wireless LAN market has its roots in two grants of unlicensed and unregulated spectrum by the FCC and development of standards adhered to by 140 manufacturers.

Connecting a computer to a wireless network has never been easier, and the most common standard for wireless networking, the Institute of Electrical and Electronics Engineers Inc.'s 802.11b, offers 11M bit/sec. connectivity—a data rate equal to that of wired Ethernet LANs.

A range of products that comply with Wi-Fi, which is what the 140-member Wireless Ethernet Compatibility Alliance in Mountain View, Calif., calls 802.11b, are now readily available.



You can create a wireless network with just two computers, each equipped with a Wi-Fi card, in what's called an ad hoc configuration. For more computers, you'll likely need to get a wireless access point—a radio receiver/ transmitter and antenna that hooks up to a wired network, router or hub. This is called an infrastructure configuration. Access points are available in many different forms, some combined with cable or Digital Subscriber Line modems, routers and firewalls.

Wi-Fi is rapidly becoming a standard feature in new notebook computers. Wireless Internet connections are available in a number of public spaces, including airports, hotels and coffee shops. Competition has driven down the cost of wireless LAN (WLAN) gear; an access point and one PC card can cost less than $300.

Access points can be mounted indoors in office ceilings. They can be mounted outdoors on poles, masts or existing towers in weatherized shelters. Device antennas are either built into cases or, if they use a card, sport a knobby antenna up to 1 in. long sticking out from the card. WLANs support raw data throughput of 2M to 54M bit/sec. They have a range of several hundred feet, although some systems can cover a mile radius outdoors with tower-mounted antennas.

A WLAN's range can be extended by adding access points, with users roaming among them as they do in a cellular system. Air France Groupe has installed 160 outdoor access points at its Charles de Gaulle International Airport hub in Paris to support bag-matching operations.

Price drops in WLAN hardware, plus the labor costs of installing wired LAN cabling, have made the costs of wired and wireless LANs roughly comparable. WLANs win the race against their wired cousins on convenience—add an access point to a network, and you can serve a whole new area of a building and multiple users in a few hours.

The proliferation of WLANs has also led to the development of an "always-connected" culture, in which a growing number of users expect to be able to access information wherever they're in an office.

The unwired conference room has been replaced with the WLAN conference room or auditorium with some unsettling results: If you're making a presentation, it had better be good, or you might see bored listeners checking their e-mail.

Frequency Hopper

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