FCC PROPOSES ALLOWING UNLICENSED DEVICES TO OPERATE AT 3.6 GHz

FCC officials stressed that unlicensed use of the 3.6 GHz band could complement existing uses at 2.4 GHz and 5.8 GHz for Wi-Fi operations. “The use of cognitive technologies, coupled with other safeguards, will afford protection to the licensed satellite earth station services in this band and thus allow the band to be effectively shared,” Thomas said. The FCC in 2002 had opened an inquiry into making spectrum available for unlicensed devices, including using the “white spaces,” or unused parts, of TV broadcast bands, as well as 3650-3700 MHz. Among other issues, the NPRM considers reinstating a primary allocation for fixed satellite service (FSS) in this spectrum.

The band appears to be “ideally suited” to providing new and advanced wireless services on unlicensed devices, particularly in rural areas, said OET’s Gary Thayer. FSS downlink earth stations -- mostly on the East and West Coasts -- now use the 3650 MHz band, he said. “As a result, a large percentage of the country’s geographic area encompassing much of rural America has unoccupied spectrum available in this band for other uses,” he said.

“We tentatively conclude that we should allow unlicensed operations with smart radio techniques with fixed satellite services in these bands,” FCC Chmn. Powell said. “To ensure that we have the ability to move forward on whatever approaches will best achieve our goals regarding enhanced services, we welcome consideration of alternative proposals and approaches that could potentially allow the use of both unlicensed and licensed terrestrial services.”

Under the proposal, higher power levels would be allowed at 3650 MHz, but with a caveat that smart or cognitive technology be used to prevent interference to licensed FSS earth stations in the band. Under Part 15 rules, unlicensed devices must modify or halt operations if they interfere with licensed users. “The ability to cover larger areas as a result of allowing higher power operations could be especially critical for fostering economic viability of systems in sparsely populated areas,” Thayer said. The NPRM seeks comment on other alternatives that would allow licensed terrestrial services and unlicensed operations by segmenting the band between these users. If authorized, licensed terrestrial services could use cognitive technologies such as those proposed for unlicensed applications to avoid interference to FSS incumbents, he said.

To safeguard FSS systems, the proposal would: (1) Subject fixed unlicensed devices to a professional installation requirement and would bar them from being located in a defined protection zone surrounding each FSS earth station. (2) Require non-fixed, unlicensed devices to follow “listen-before-talk” requirements to detect the presence of any FSS earth station in the area. These devices would then have to decide whether to transmit and make potential adjustments to the transmit power. (3) Require unlicensed devices to emit a standardized ID signal that would “possibly provide contact information, as well as location,” the FCC said. “That signal would allow easy identification of possible sources if interference arises.”

The Satellite Industry Assn. (SIA) recently told the FCC it was “extremely concerned” about the potential for interference posed by unlicensed use of the 3650-3700 MHz band. SIA said that while existing use of the band is concentrated along both coasts, new earth stations aren’t necessarily geographically limited. It also cautioned that interference mitigation techniques such as adaptive frequency hopping may not work to protect earth stations.

The 3650-3700 MHz band has been sought by wireless ISPs (WISPs) for both backbone traffic and end-user broadband access. “Not too far down the road, we may need to examine more spectrum below 1 GHz and also higher power levels -- maybe even a band dedicated specifically for outdoor use, to give WISPs the spectrum tools they need to compete effectively on a large scale with cable and DSL,” Comr. Copps said: “I would look to the satellite industry to help us create a way to allow unlicensed operation without unacceptable interference.” That industry could help the Commission figure out how cognitive technology protections could be perfected and to identify the right power levels, he said.

Comr. Adelstein noted that at an FCC WISP forum last year, these providers called for more spectrum and higher power levels to serve sparsely populated areas. A “balance” has to be struck between new services that can be offered in the band and incumbents, he said. “We're considering reinstating a primary allocation for FSS, which could also allow us to maximize use of this band as we go forward,” he said. FCC rules grandfather about 65 FSS operations with a primary allocation, Thomas said. The question teed up in the NPRM is whether an additional 30 earth stations and any others that would go into operation in the band should be granted primary allocation as well, Thomas said.

An interesting aspect of 3.6 GHz for unlicensed use is that it sits in the middle of 2.4 GHz and 5.8 GHz, where Part 15 operations are allowed, Thomas said during a media briefing after the meeting. This makes it possible for manufacturers to build a single device that could operate on all 3 bands, generating additional bandwidth, he said.

The original NOI adopted in Dec. 2002 had considered use of the white spaces in broadcast spectrum for unlicensed operations, in addition to the 50 MHz at 3.6 GHz. Last year, NAB and the Assn. for Maximum Service TV asked that the FCC not allow unlicensed devices entry into broadcast spectrum until the DTV transition is complete.

“What we decided to do is bifurcate them,” Thomas said of proposals on 3.6 GHz and broadcast spectrum: “We will be moving forward shortly with the other half.” Thomas said the spectrum proposals were divided because both are significant and “we wanted to allow full debate.” He said OET plans to present a separate NPRM covering the broadcast spectrum proposal “rather quickly.”