House Wants Answers on Receivers' Role in Spectrum Sharing

Eyes Closer Spectrum Quarters and Impact on Current, Future Users

The House Communications Subcommittee wants industry input on Thursday on how to allow spectrum users, like broadcasters, wireless companies and the government, to occupy increasingly close quarters without "stepping on each other's toes."

That is according to a majority staff memo on a Nov. 29 hearing in the subcommittee on "The Role of Receivers in a Spectrum-Scarce World."

The issue is growing in importance given a number of FCC initiatives to boost spectrum efficiency and use, including allowing unlicensed devices to share the so-called "white spaces" in the broadcast band, moving broadcasters to make room for wireless companies, the FCC's so far unsuccessful attempt to allow LightSquared to operate alongside GPS spectrum, and the FCC's recent move to loosen rules on terrestrial use of satellite spectrum.

"Good fences make good neighbors," say the staffers, "but how do you know how high to build your fence or what materials to use if you don't know who your neighbors might be in the future or precisely what they will be doing on their lot?"

They point out that the two main "fences" are guard bands on the spectrum side and filters and power limits on the transmitter/receiver side. Some of the questions that the subcommittee majority wants answered include:

"Can smart engineering and forward-looking spectrum strategies account for the possibility of unanticipated technologies and uses in adjacent spectrum bands and help prevent today's decisions from limiting flexibility in the future? How do we promote such flexibility without unreasonably increasing the cost of services and devices," emphasizing the receiver side of the fence.

A spotlight was put on the receiver issue by the failure of LightSquared ultimately to secure an FCC waiver to use its satellite spectrum to create a wholesale, terrestrial mobile broadband network. The FCC initially granted the conditional waiver, but put that effort on hold -- and LightSquared into bankruptcy -- after it was determined that sensitive GPS receivers in an adjacent band were being interfered with because they were picking up in-band transmissions, meaning that LightSquared's transmissions were within its band, but the GPS receivers were picking them up anyway.

Government users are also being called on by the Obama administration to find ways to share more of their spectrum with commercial users.

More recently, Dish network has complained that the FCC's new proposal to loosen restrictions on terrestrial use of satellite spectrum Dish owns would "cripple" their plans for a wireless 4G network because of restrictions that protect an adjacent -- currently unoccupied -- band from interference. That issue is not directly addressed in the memo, but could be brought up in the hearing.

Scheduled to testify at the hearing are Brian Markwalter, senior vice president, Consumer Electronics Association; Ron Repasi, deputy chief, Office of Engineering and Technology, FCC; and Pierre de Vries, senior adjunct fellow, Silicon Flatirons Center, University of Colorado.