Wireless frequency meltdown predicted

The Radiocommunications Agency (RA) has warned that the 2.4Ghz band could become so populated in some areas that all wireless devices that use the frequency would crash.

The 2.4Ghz band is designated for use by industrial, military and scientific applications. The Bluetooth standard, and systems such as SpectraLink - which uses the 802.11 standard and was last week installed in Guys and St Thomas' hospitals in London - use spread spectrum technology to vary the frequency of transmissions. This gives developers more bandwidth to accommodate devices.

But a senior engineer at the RA said the technology, developed in the 1940s by the military because it was undetectable, is flawed.

"Its Achilles heel is co-existence with similar systems. Graceful degradation of signal occurs as the number of devices using the band in a local area increases," she said.

This means that instead of the last user finding themselves blocked when the channel is full, every signal that is operating degrades. "Once there are too many devices operating, they all cease to function. When one falls down, they all fall down," she warned.

The RA spokeswoman said that as more commercial applications utilise the band, 'hot spots' could occur in areas where many devices are collocated.

"The City of London could be such a hotspot. But the parameters of what might cause that are difficult to define, mostly because there's just not the volume of devices yet. The technologies can coexist, but it's the number of devices that could overwhelm the band," she said.

Martin Brampton, research director at Bloor Research, said that the RA should license the 2.4Ghz band, and called for urgent research. "If this issue isn't thought through now, the whole thing's liable to fall apart and none of these standards will prove reliable for users," he said.

The RA is so concerned about the dangers, it is re-evaluating the use of the 2.4Ghz band and is putting forward proposals to the government.

"It's turning out to be more complicated work than we originally imagined. There's a lot of users out there," a spokeswoman said.

John Seymour, product manager at Bluetooth vendor Red-M, admitted that this was possible, although only "a worst-case scenario".

See also:

Microsoft puts Bluetooth on ice

Microsoft said that its next generation operating system, Windows XP will not initially support the next-generation wireless protocol, Bluetooth.  04 Apr 2001

Dispute over impact of Bluetooth

The Radiocommunications Agency has cast doubt on a report which claims that Bluetooth will not significantly affect other devices that use a key unlicensed radio band.  24 Jan 2001

The promise of Bluetooth

The first Bluetooth product has arrived in the shape of a wireless headset for mobile phones, but the real promise of the technology would appear to be in providing users with 'always-on' access to the internet.  11 Jan 2001

The promise of Bluetooth

The first Bluetooth product has arrived in the shape of a wireless headset for mobile phones, but the real promise of the technology would appear to be in providing users with 'always-on' access to the internet.  11 Jan 2001

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