More tinkering on the way for wireless ISP spectrum

Wireless Internet service providers (WISPs) in the U.S. that face growing Wi-Fi interference are excited about a radio band that was set aside for them on Friday, but industry and government still need to thrash out some key details.

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Under rules that became effective Friday, the U.S. Federal Communications Commission (FCC) allows WISPs to use frequencies between 3650MHz and 3700MHz, a band that is already utilized by satellite Earth stations and radar stations on both coasts but largely unused in the middle of the country. There, many sparsely populated areas have not been reached by DSL (digital subscriber line) or cable Internet services and have turned to WISPs, generally small operators that can't afford to license spectrum.

The band is sizable, big enough for broadband services from two or more WISPs in any given area, according to industry participants.

Even though the rules are effective now, apart from a few minor details that need separate approval, WISPs can't use the spectrum yet because no devices have yet been approved for the use, according to a senior FCC official. In addition, the agency was due to receive petitions for reconsideration on Friday, in which industry and the public could ask for changes in the rules. Considering and implementing such changes typically takes months, the official said.

How the final rules shape up has implications for the radio environment a provider will face and what kind of equipment becomes available. Equipment vendors and service providers are looking for greater clarity from the FCC because they see a major opportunity at stake: If the rules are crafted the way some would like to see them, WISPs may be able to use the emerging WiMax wireless broadband technology and reap the benefits of volume economics.

The WiMax Forum, which will certify WiMax equipment for specific radio bands, has no plans on the table for certification testing in that spectrum, said Aditya Agrawal, co-chair of its Certification Working Group. But the band is nearby the 3.4GHz-to-3.6GHz spectrum that will be used by the first approved WiMax products, expected late this year. Certification in the 3650 band could be added later if there is enough demand, he said.

Most WISPs use unlicensed spectrum, especially the band around 2.4GHz that is also used by IEEE 802.11b and 802.11g Wi-Fi equipment. Many use Wi-Fi technology themselves, reaching their subscribers over long distances by using special outdoor antennas to extend range. But the phenomenal popularity of low-priced Wi-Fi access points among consumers has caused headaches.

"My WISP is located in [radio frequency] hell," Michael Anderson, co-owner of PDQLink Wireless, in North Aurora, Illinois, wrote in an e-mail interview. "I drove home from one of my towers a few weeks ago. ... the distance was less than eight miles. My laptop picked up over 404 access points." The radio waves produced by those home access points can go beyond the walls of the house and interfere with a WISP's longer range transmission, he said. Anderson also is chairman of Part-15.org, an group of WISPs.

Last Mile Wireless LLC serves more than 300 local residences and businesses in Preston, Idaho, where DSL and cable aren't available and dialup speeds are slow, according to TJ Burbank, a partner in the company. The operator's 2.4GHz long-range, directional Wi-Fi service runs into interference from another WISP's 2.4GHz network, and Burbank is looking forward to getting access to more unlicensed spectrum and being able to use WiMax.

"Unless we add additional broadcast locations on the other side of the valley ... we really can't add much more 2.4GHz stuff now," Burbank said. "We would love to own a piece of spectrum, but if it's going to be US$50,000 a year or something, we'd be more willing to deal with the interference," he added.

In response to requests from WISPs, the FCC proposed allowing new uses of the 3650MHz-to-3700MHz band, with restrictions to prevent interference with the satellite Earth stations. The rules for the band call for "non-exclusive" licensing, under which service providers would not have to buy a license but would have to register their base stations with the FCC and show that they were not interfering with an existing user. Among the rules is a requirement for "contention-based" methods for preventing interference among multiple users. The FCC left it to industry to determine how it would meet the contention requirement.

Contention in wireless networks generally means the way two transmitters negotiate when they are using the same channel at the same time, said Mitch Vine, director of strategic marketing at wireless broadband equipment vendor Redline Communications Inc. Basically, a transmitting station "listens" for someone already transmitting in that channel, and if it detects someone, it holds off. If this is what the FCC is demanding in the 3650 band, WiMax would not comply, Vine said. In its current form, WiMax instead puts senders in different time slots where they have a given frequency to themselves, he said.

Vendors and service providers said it's not clear what the FCC means by a contention-based system. They don't all agree on how hard it will be to resolve the issue.

"The industry could come up with something, but it's going to take time. It's not a trivial thing to do," Vine said.

At least two vendors have something to say about the contention requirement.

"We'd like to see that either clarified or removed so that the 3650 band becomes open to any technology, including WiMax," said Alan Menezes, vice president of marketing at Aperto Networks Inc., a wireless broadband vendor readying products for WiMax certification.

Intel Corp., a strong backer of WiMax, sees the contention issue causing delays and wants that stipulation removed, said Peter Pitsch, communications policy director. The WiMax Forum's petition also asked the FCC to remove the contention requirement, said Margaret LaBrecque, who heads the organization's regulatory arm.

An executive at one WISP is more optimistic.

"I think people will get through that issue," said Jeff Thompson, founder, chief operating officer and president at TowerStream Corp., which offers fixed wireless services in several U.S. cities including Chicago, New York and Boston.

In addition to confusion over the contention requirement, the requirements for use of the spectrum puts service providers in a bind, according to Paul Sinderbrand, an attorney at Wilkinson Barker Knauer LLP, in Washington, D.C., who represents the Wireless Communications Association (WCA), a group of WISPs, wireless vendors and consultants. Those who sign up to use the band are required to make sure they won't interfere with someone already using it in that area. But because there is no established mechanism for enforcing the spectrum rules, at the moment the FCC can offer users no recourse if a later user interferes with their use of the band, Sinderbrand said.

"There's this sort of Damocles sword hanging over anyone who deploys, at least until the commission clarifies," Sinderbrand said. In its petition Friday, the WCA recommended that the FCC divide the spectrum into two 25MHz blocks, one of which would have traditional licenses while the other remains under non-exclusive licensing, he said.

Intel originally advocated licensing the band everywhere, but now it says the FCC should issue licenses in the 50 largest metropolitan areas and leave the frequencies unlicensed everywhere else. Faced with the prospect of many other operators going after potential customers in a dense urban area, service providers won't invest in building a network, Pitsch said.

TowerStream's Thompson and Part-15.org's Anderson think that just requiring users to register their base stations will create a better environment than the crowded 2.4GHz band. Though the FCC cannot guarantee that operators won't interfere with each other, the rules set up a framework where interference issues can be worked out, Anderson said.

The WCA's Sinderbrand and others are hopeful that despite the uncertainties, the rules will turn out well.

"I think what you're going to see, when this all washes out a year from now, is probably a pretty creative licensing approach from the commission," Sinderbrand said.