The FCC has sought input on whether it can take a dynamic approach to interference protections between wireless companies and TV broadcasters after the incentive auctions, or whether it must create minimum geographic separations.
Some broadcasters (notably Sinclair) and wireless companies have argued for minimum geographic separation if the FCC uses a variable band plan that will have broadcasters and wireless companies using the same or adjacent channels—proposals for such separations range from 100 kilometers to 500 kilometers.
But the FCC said those proposals came with "limited" technical analysis. "We are concerned that prescribing a pre-defined separation distance as proposed by some commenters may be spectrally inefficient and overly conservative," the FCC's Office of Engineering and Technology (OET) said in a public notice requesting comment.
OET wants more input on the potential for adjacent and co-channel interference under four different scenarios, and more to the point how on "an alternative methodology that could enable the Commission to accommodate market variation in a more spectrally efficient manner than that proposed by various commenters."
Those scenarios are:
(1) "DTV transmitter-into-wireless base station (uplink) interference," which the FCC says could require the largest separation given that the transmitter and receive antenna are high enough to have potential line-of-site interference path.
(2) "DTV transmitter-into-wireless user equipment (downlink) interference." Not as much separation needed since user equipment is typically at ground level or signals are already weakend by in-building propagation issues.
(3) "Wireless base station (downlink)-into-DTV receiver interference."
(4) "Wireless user equipment (uplink)-into-DTV receiver interference."
Comments are due by Feb. 28. The FCC said this week it plans to release a report and order for the incentive auction framework by spring.