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Surge in popularity spawns new ideas for wireless LANs.

Wireless LANs are breaking out of their slump and starting to enjoy the popularity long expected of them.

No longer hampered by slow speeds and lack of standards, wireless LANs are finding more widespread use in facilities that are difficult to wire, such as factory floors and old office buildings, and in LAN environments where moves, adds and changes are common. Wireless LANs are also benefiting from the growth of "nomadic computing" and the need to provide temporary links for ad hoc work groups.

Business Research Group of Newton, Mass., estimates U.S. users will spend $65 million on wireless LANs in 1994--nearly double 1993's rate. BRG projects similar growth in 1995, with sales reaching $100 million.

Wireless LANs typically employ a hub-based configuration. The nodes, which may be stationary desktop or roving notebook computers, use a wireless adapter with radio circuitry and an antenna to communicate with the hub. The hub, or access point, also has an antenna and usually an attachment for connecting with wired LANs.

Most wireless LANs use unlicensed radio bands starting at 902 MHz and 2.4 and 5.8 GHz and employ spread-spectrum techniques--where the transceiver sends and receives the signal over a range of frequencies--to reduce interference. (See COMMUNICATIONS NEWS, July 1994, page 51.)

In the wireless LAN standard being developed by the IEEE 802.11 committee, data will be transmitted at 2 Mb/s with a frequency-hopping spread-spectrum system.

The IEEE specification was originally developed by Proxim, Inc., which has incorporated the technology into its new RangeLAN2 wireless network adapters. Currently the adapters operate at 1.6 Mb/s, but the Mountain View, Calif., firm is tuning its product to reach 2 Mb/s.

Market leader AT&T Global Information Solutions uses direct sequence spread-spectrum techniques with its WaveLAN products, claiming this gives even better protection against interference and eavesdroppers. This approach divides the band into a small number of wide frequency channels, so it offers greater bandwidth. WaveLAN runs at 2 Mb/s, with a range of 10 to 180 meters, depending on the environment.

Access to existing wired LANs is provided by WavePOINT, a compact processor with wired and wireless LAN interface cards and an omnidirectional antenna.

Solectek Corp. uses At&T's spread-spectrum technology in its AirLAN/Bridge to connect Ethernet LANs up to three miles apart with a throughput of 2 Mb/s. The San Diego, Calif., firm also offers AirLAN wireless adapters and a wireless Ethernet hub.

Motorola's Altair Plus II is the third generation of its wireless LAN family, offering a throughput of 5.7 Mb/s with SNMP management. Its Control Module attaches directly to an existing Ethernet, or may be connected to a file server or used to create an independent LAN. Each module can operate with 50 user modules in a work area of up to 50,000 square feet. Network managers can expand the range by using multiple command modules with non-overlapping frequencies.

Each user module, in turn, can support as many as eight devices. Since the Altair modules attach directly to an existing Ethernet adapter, you can connect anything that supports Ethernet, including Macintoshes, network printers and other peripherals.

For linking buildings, the Arlington Heights, Ill., firm offers VistaPoint modules that provide wireless point-to-point connections of up to 3,940 feet with most of the same management features as the Altair Plus II.

IBM is among the latest to enter the wireless LAN market, with a range of network products operating initially with NetWare and OS/2 LAN Server. IBM's Wireless LAN includes a PCMCIA client adapter and an ISA/Micro Channel PC card for use in a base station. All communications are channeled through the base station, which can attach to Ethernet or token-ring wired LANs.

Reportedly, the LAN can extend up to 100 yards from the base station inside an office building and over twice that range outside. It operates in the 2.4-GHz range with a throughput of 1 Mb/s, using spread-spectrum transmission. Features include four-fold data compression, encryption and SNMP management.

Fellow newcomer Xircom, Inc., of Calabasas, Calif., is targeting nomadic PC users with its Netware Cordless LANs. Its Netwave PCMCIA and parallel port adapters provide connections to wired Ethernet and token-ring LANs through an Access Point, using spread-spectrum transmissions in the 2.4-GHz range. Netwave has a data rate of 1 Mb/s and a range of 50 meters between nodes.

Data communications consultant Morris Edwards serves as program chairman of the Network Computing Solutions Conference and Exposition (NetCom), to be held in Charlotte, N.C., Oct. 12-13 and in Ft. Lauderdale, Fla., March 1-2, 1995.
COPYRIGHT 1994 Nelson Publishing
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Copyright 1994 Gale, Cengage Learning. All rights reserved.

 
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Author:Edwards, Morris
Publication:Communications News
Date:Aug 1, 1994
Words:770
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