Getting Around Antenna Limits

By Adam Stone

July 28, 2004

The FCC's Part 15 rule says you can't mix and match Wi-Fi equipment and antennas willy-nilly. Despite this little known and unenforced fact, some vendors are turning the rule in their favor.

When is a constraint not a constraint? When money -- and marketing -- will solve the problem.

The problem in this case is the FCC's Part 15 rule, which tries to control manufacturers of wireless antennas and other equipment. Specifically, Part 15 says that you cannot mix and match antennas with Wi-Fi gateways. Only antennas that were certified with a particular gateway can be used with that device. Meaning, you could buy a third party antenna -- but it was technically illegal to hook it to your access point. Not that anyone has every been in trouble for it.

In theory, this rule is bad news for equipment manufacturers looking to add more range to their Wi-Fi systems, insofar as it limits the possible combinations of equipment. In practice, though, recent examples suggest that manufacturers have found a way to bring to market a new generation of antennas while staying well within the bounds of Part 15.

Take for instance Linksys, a division of Cisco Systems , which recently released a number of new antenna products, including a pair of TNC Connector Antennas (HGA7T), a single SMA Connector Antenna (HGA7S) and Antenna Stands (AS1SMA and AS2TNC) for mounting the antennas to walls or ceilings. More important, Linksys made the rather exhaustive effort to have each of these new antennas approved for use with a range of existing devices, creating in effect a grid of cross-approved products.

This effort reportedly cost Linksys a few hundred thousand dollars in fees and associated expenses, although the company would not confirm this figure.

In spite of the added expense, Linksys espouses the party line generally held by device manufacturers in relation to Part 15. "We don't see it as a hindrance," said corporate spokesperson Karen Sohl. "We see it as a benefit for our customers. If we are getting approved through a body like the FCC, customers can feel safe that the products are going to work and that they are going to be safe for use."

There are other reasons for device makers to be grateful for Part 15, even if it does sometimes restrict their marketing options.

In the first place, the effort to discourage cross-pollination has helped speed public acceptance of Wi-Fi, by ensuring a certain level of reliability. "If you got five e-mails every time you pushed you garage door opener, it wouldn't have worked as well," said Iain Gillott of iGillott Research in Austin, Texas.

Moreover, most in the Wi-Fi community have simply come to accept Part 15 as the price of doing business -- and rightly so, said Gillott. The rules were in place long before Wi-Fi came on the scene, and Wi-Fi accepted the rules as the entrance fee for joining the unlicensed spectra.

"You can't go back to the FCC later on and say: We don't like these rules," he says.

Like them or not, it's clear that antenna manufacturers have decided to live with the Part 15 rules, even as growing public demand pushes the need for new antennas with higher gain. Network connectivity provider D-Link for instance expanded its wireless antenna offerings in July with 2.4GHz Omni-Directional (ANT24-0400) and 2.4GHz Directional (DWL-M60AT) antennas. Both can be used to select D-Link 802.11g and 802.11b products to expand the range of a home or small-business wireless network.

Some analysts say the release of such products is the natural outcome of evolutions within the Wi-Fi user community. In effect, the need for mix-and-match products is a logical business step in a market that demands increased performance levels.

"As implementation matures and performance issues become more and more important, the antenna functionality may need to change," said Philip Marshall, an analyst with the Yankee Group. As a user, "you may try to deploy this and it may work, but the RF environment may change and then your antenna capabilities may need to change. [As the vendor in this scenario] if you have a range of antennas and a range of gateways, you would want to mix and match to get the best solution out there."

That's essentially the case being put forward by Linksys as it moves to build momentum for its new interchangeable products.

"Most users are pretty happy with what they have, but maybe they have an environmental challenge. Maybe it's a four-story house, with an office in the attic or the basement, and the signal is not as strong in those places," Sohl said. Rather than lose those customers to another manufacturer, she suggested, it makes sense to encourage users to extend their Linksys systems with further Linksys products.

Analysts see sound business logic here. These manufacturers "are making the assumption that Part 15 is not going to change, and that the majority of people are going to continue using unlicensed 802.11 networks. And I would say that those are both pretty good bets," said Gillott.

All that being said, recent actions by the FCC suggest Part 15 maybe be evolving in a way that gives manufacturers more latitude.

FCC rule 04-165 issued July 12 broadened considerably the rules under which antennas and other wireless devices can be cross-approved for use with one another. Under this paradigm high-gain antennas of each major type can be tested. Once approved, the manufacturer can release the characteristics of those antennas, at which point other antennas that fall within those characteristics and are not of a higher gain could be easily approved.

This process could make it significantly less expensive for a manufacturer to create the sort of grid Linksys recently produced. But there's a possible downside. By making it easier to get antennas and devices cross-approved, the FCC also has made it easier for third parties to get antennas approved for use with their competitors' products.

Thanks to Wi-Fi Networking News for bringing the Part 15 antenna rules to our attention.



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