Sirius Spectral Problems for 802.11b

By Ed Sutherland

March 19, 2002

A storm is brewing between satellite radio providers and devices in the unlicensed 2.4 GHz band (802.11b). Watch it develop here!

A proposal before the Federal Communications Commission (FCC) could squelch red-hot wireless devices operating on the 2.4 GHz frequency. The call by a satellite radio company to silence Wi-Fi, Bluetooth and other popular mobile technology has a wireless trade group girding for a "battle royale."

Robert Primosch, a lawyer for the Wireless Communications Association (WCA), says a petition by Sirius Satellite Radio Inc., asking that emissions from devices on the 2.4 GHz frequency be sharply curtailed, "is being taken seriously" by the FCC. Primosch says the FCC will likely call for public comment on the petition later this year.

The New York-based Sirius, set to launch nationally later this year, told federal regulators that out-of-band emissions from countless devices using the unlicensed 2.4 GHz frequency could hurt the satellite industry's $3 billion investment in technology.

Weakening W-Fi
Satellite radio services use the licensed 2.32 to 2.34GHz frequency. The unlicensed wireless services occupy the nearby 2.4 - 2.483 GHz band. Sirius contends that the FCC should reduce the power of unlicensed devices by a third -to 'just enough' to transmit their 2.4 GHz signal.

As 2.4 GHz devices, in the form of 802.11b or Bluetooth, find their way into PDAs, laptops, and cell phones, Sirius believes stray signals from one of the unlicensed wireless devices could interfere with in-car receivers, causing poor reception and incurring the wrath of a lot of angry customers.

Primosch told a recent gathering of wireless Internet service providers that a "battle royale" between licensed and unlicensed operators is inevitable, but providers could affect the FCC's ultimate decision during the upcoming public comment period.

"The situation needs to be monitored carefully," Primosch says.

The petition by Sirius points to past decisions of the FCC to curtail emissions interfering with digital satellite service and broadcast television.

Deja Vu All Over Again?
The dispute between satellite radio and unlicensed wireless services is a near-mirror image of a flare-up between the satellite broadcasters and licensed wireless carriers that seems headed for resolution.

Although their signals originate from space, the strengh of satellite radio broadcasts erodes in urban areas with buildings that obstruct transmissions. To remedy the situation, satellite radio services XM and Sirius received temporary approval to build repeaters that boost the original signal's strength.

Cell phone networks complained that the high-powered repeaters would interfere with new next-generation services. Carriers asked the FCC to drop the repeaters' signal strength from 40 kilowatts to two killowatts.

But with XM already having 778 repeaters and Sirius 104, and both satellite radio services underway, insiders expect the FCC to make the temporary approval to use repeaters permanent.

If residents of the unlicensed spectrum get their wings clipped, 802.11b's headache could be a boon for people like David Gurevich. Gurevich's company, UltraDevices, uses 802.11a technology to bring wireless broadband service to people not served by DSL or cable modems. Unlike Bluetooth and Wi-Fi, 802.11a operates between 5 and 6GHz, posing fewer potential interference problems.

The satellite radio threat to 2.4GHz devices may turn out to have a silver lining. Sirius' objections to unlicensed 2.4GHz services may actually accelerate the inevitable move toward a roomier 5GHz frequency and faster 802.11a technology. Already, companies such as Atheros are charging into 802.11a and multiple standard chipsets.



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