802.11a: Faster Wireless

Introduction
802.11a is  higher speed (54Mbps) variant of the 802.11b technology now commonly used in many unlicensed spectrum (local range) wireless networks.  This article details the pros and cons of the new standard, and looks at what's ahead.

Pros:
Faster
Little or no interference with 2.4 GHz devices, due to its use of the 5GHz spectrum.

Cons:
shorter range
802.11a is not compatible with either 802.11b or the other IEEE 54Mbps/sec "standard," dubbed 802.11g.

A May 18, 2002 posting by "flatulus" (heh) at Slashdot provides some useful technical information on current implementations. Most notably, the vast majority of current implementations of 802.11a are based on a chipset by Atheros. (Other chipset providers are Resonext and Intersil.)

The 54 Mbit/sec (or 72 Mbit/sec “turbo”) mode of 802.11a is extremely range limited. At 100 ft, notes flatulus, 802.11a drops back to a speed which is very close to 802.11b.

Note also that, although 802.11a is not compatible with either 802.11b or 802.11g, Intel, Agere and other manufacturers offer dual-card base stations which can hold both 802.11a and 802.11b cards, in order to support both standards. (Read more at ZDNet UK....)

Wireless Access Points based on the Altheros chipset include:

• Linksys WAP54A wireless access point

PCI Cards based on Altheros 802.11a chipset:

• Proxim 802.11a Mini PCI card

PC Cards based on Althereos chipset:

• Linksys WPC54A

802.11a products are also available from D-Link, Intel and SMC. According to reports, the current Intel product is limited to 54Mbps/sec rates.

According to a June 17, 2002 report at thinksecret.com, Apple Computer Inc. has made the internal decision to adopt the IEEE 802.11g wireless networking standard in future versions of its AirPort technology. Noticeably absent from this rumoured AirPort update is support for 802.11a.

For Further Reading:

• For more information, see part 2 of our wireless networking feature.
• See also: 802.11b's Dirty Little Secret