Martin Courtney

It may be too early to predict the demise of the 802.11a wireless LAN (WLAN) standard, given its small but potentially lucrative base of customers across the UK, who may want to expand or upgrade their networks at some point.

But if 802.11a is, like Betamax video, to gradually disappear from view, how will history judge a standard that was originally touted as the natural successor to the slower 802.11b specification?

Ironically, one of the factors lauded as a major advantage of 802.11a, namely its use of the 5GHz spectrum, may also turn out to be its Achilles heel. The 2.4GHz waveband used by 802.11b was famously described as a dumping ground for any form of wireless radio equipment that did not attract a wireless licence fee. Many in the networking industry predicted that 802.11b WLAN traffic would slow to a halt under the weight of multiple devices saturating the available spectrum.

This forecast has actually turned out to be true within convention centres and trade halls such as Cebit, where unusually high numbers of 802.11b users often gather. But, so far at least, it has not proved such a problem within carefully planned corporate WLANs, where IT managers have conducted site surveys and installed sufficient numbers of wireless access points.

We were told that companies wanting to avoid congestion problems within the 802.11b frequency should turn to the 5GHz spectrum. In contrast to 2.4GHz, the 5GHz spectrum was clean, interference-free and had bags of capacity to handle any amount of data that the future would throw at it.

The reason why so few organisations have bought into 802.11a so far is simple, however - laws controlling the use of the 5GHz spectrum varied widely from country to country.

In some European countries, including the UK at one time, you had to buy a licence if you wanted to use equipment that transmitted in the 5GHz waveband. By the time the UK dropped that requirement, 802.11g equipment - just as fast as 802.11a but backwards compatible with 802.11b hardware - had already started to appear on the market, providing corporate customers with a better alternative.

In fact, it could be argued that the low uptake of 802.11a kit is largely due to the fact that US vendors failed to modify their 802.11a products to comply with local legislation. Or in some cases even failed to see that there were licensing issues to be resolved.

It has not yet been decided whether the proposed 108Mbit/s 802.11n will use 5GHz or 2.4GHz, but the fate of 802.11a will depend on the choice.

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