Will Wi-Fi overwhelm satellite radio?
Published: 08 Apr 2002 14:56 BST
New satellite radio services in the US that transmit music and talk to cars and homes are looking askance at the blossoming 802.11b market, claiming that interference from wireless networks may hurt their commercial prospects.
The two wireless industries broadcast their signals on radio waves separated by only a small buffer. So far, that buffer has kept the millions of Wi-Fi networks from interfering with radio broadcasts by Sirius Satellite Radio or XM Satellite Radio.
But the radio companies don't think the relative calm will last, so they are asking the US Federal Communications Commission to step in. Within a few years, they say, interference from the huge number of people using Wi-Fi's signal will bleed through that buffer and snarl their signals, blasting listeners with the kind of hissing, pops and humming that overwhelms a radio receiver placed too close to a mobile phone.
Although there are no plans to run similar satellite radio services in Europe, any changes to the 802.11b standard will increase the cost of wireless network cards and may even force a recall of existing systems.
"The objective is to get it so people can use (Wi-Fi) and listen to satellite radio at the same time. What we're trying to do is head off a future problem," said Sirius Satellite Radio co-founder Robert Briskman.
Radio waves from different services have to coexist in the air, and while putting them on different frequencies keeps them separate it is impossible to completely eliminate spurious transmissions on adjacent frequencies from those allocated to a transmitter. All transmitters have filters to reduce these to tolerable levels, but the argument revolves around whether the current 802.11b specification is tight enough, especially when the predicted increase in use happens.
Sirius and XM have asked the FCC to consider imposing more regulations on Wi-Fi makers, including forcing them to put greater controls than already exist in the standard. The FCC is not required to act upon their request.
"There is no problem right now. As (Wi-Fi) proliferates, there could be one -- and a serious one -- and we're trying to head that off," said Briskman, adding that the companies have developed a filter that Wi-Fi makers could use to control their signals.
"No basis" for concern
But Wi-Fi proponents, including gear makers and network operators, don't believe there will ever be an interference problem, so they shouldn't have to face more regulations or add something to their equipment that could increase the cost.
"There are surveys that show you can pick up (Wi-Fi) access points continuously through some major urban areas, and we're not causing any problems," said Jim Zyren, director of strategic marketing for Intersil, which makes most of the world's Wi-Fi chips. "There's no basis for their request."
People who are setting up the networks are even more vehement.
"It's just absurd," said David Sifry, chief technology officer for Sputnik, a Wi-Fi network now in the building stages. He says the request is equivalent to asking them to "break the laws of physics" since it would require them to keep the stray emissions at a level equal to the amount of radiation emitted when water evaporates in sunlight. "It's that level of insanity you can't legislate."
The number of Wi-Fi networks, an inexpensive and increasingly popular form of wireless networking, is expected to double in the next 18 months.
Short for "wireless fidelity", Wi-Fi is predicated on the technical standard 802.11, which requires the installation of a small radio tower connected to the Internet via a high-speed phone line or digital subscriber line connection. The radio, about the size of a can of beer, extends the wire line and connects with any mobile devices equipped with mini-radios in PC cards.
Setting up a network is relatively inexpensive, costing £200 to £700 to set up a system that allows wireless access in a 300-foot radius. It's already in about 1.4 million US homes and is catching on in restaurants, hotels, airports, workplaces and conference centres. By 2005, analysts believe, Wi-Fi will exist in about 27 million homes and 28 million offices with these networks.
In the airwaves, the lower end of US satellite radio transmissions travel at 2,345MHz, while the upper range of the 802.11b Wi-Fi standard operates at 2,400MHz. A blank buffer sits in between the transmissions.
Who would pay?
The satellite radio stations insist they are not trying to end the Wi-Fi industry; they're just trying to reach a peaceful coexistence. But the makers of Wi-Fi chips and equipment would likely have to bear the brunt of the cost if federal regulations were imposed.
Adding new equipment and materials into the manufacturing process could add about 30 percent to the cost, according to Intersil's Zyren.
Added Andrew Weinreich, chairman of Joltage, which also sells Wi-Fi Internet access: "The fix is just as easy on their side -- their antennas can better distinguish their signal."
In a few years, just when satellite radio stations are anticipating an interference problem, the issue might be moot, because Wi-Fi has been evolving -- and moving into a different radio spectrum.
The majority of Wi-Fi networks use the 802.11b standard. But there is another kind of Wi-Fi network that uses the 802.11a standard, which operates in a different radio spectrum and, thus, wouldn't be an issue for the satellite radio stations. If 802.11a becomes the more popular standard, which is likely since it is considered safer and faster than 802.11b, the problem simply goes away.
The first generations of 802.11a chips, from companies such as Proxim, are just now hitting store shelves.
And there is a chance the FCC may choose to act even if it doesn't have to. The commission has a history of treating the satellite radio companies kindly, said Robert A. Saunders, an analyst with consulting firm Eastern Management Group. In a dead heat, Wi-Fi might lose out, he said.
"The FCC has taken a very protective approach -- make sure they have enough room to breathe," Saunders said. "It treats XM and Sirius like babies, hatched this industry, carved out spectrum, made sure there were two companies so there was competition. They will act to make sure their spectrum remains pretty clean."
ZDNet UK's Rupert Goodwins contributed to this report.
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