The Dangers of Using White Space Spectrum
As a wireless designer I have been looking forward to using the TV White Spaces for various applications, but I fear this may have been a wait for nothing. The White Space spectrum saga has been long and has not yet met its promise, but it may soon be effectively killed by the FCC Voluntary Auction.
The process to allow unlicensed use of the White Space started in 2002 and only recently stabilized with the release of FCC 10-174 2nd Memorandum Opinion and Order on May 19, 2011. Recently, the FCC has launched a voluntary auction with the goal of consolidation much of the unused UHF TV spectrum (White Space) into larger blocks so it can ultimately be used by the cellular mobile business.
The following excerpt from FCC 12-118, NPRM Expanding the Economic and Innovation, Docket No. 12-268, “Opportunities of Spectrum Through Incentive Auctions” explains the FCC’s plan.
“Repacking will enable us to configure a portion of the UHF band into contiguous blocks of spectrum suitable for flexible use.”
One might wonder what “flexible use” means, however you need look no further than the next paragraph to see that the spectrum is intended for competitive auction.
“The forward auction will resemble prior competitive bidding systems that the Commission has utilized, but with important differences. Its interdependence with the reverse auction and the repacking..”
Further explanation is given in the auction FAQ with respect the Commission‘s expectations.
“ .. a broadcaster would formulate its price to return its UHF spectrum to the FCC for auction, in exchange for a share of auction proceeds plus an assigned frequency in the VHF spectrum.”
While the words in the speeches say comforting things, the numbers do not.
“Television white spaces will continue to be available for unlicensed use in the repacked television band, and we propose making two channels currently designated for wireless microphone use available for white space devices. In addition, we propose to make the guard-band spectrum in our proposed 600 MHz band plan available for unlicensed use, and propose to allow unlicensed operations in channel 37, with protections for incumbent radio astronomy and wireless medical telemetry operations. [i]” (Emphasis added).
I interpret these words as two channels with interference from microphones and one partially restricted by radio astronomy with the rest being up for auction, but I am open to hearing other interpretations. Regardless, we are talking about three TV channels or 18 MHz, an amount significantly smaller than the 900 MHz, 2.4 GHz or 5 GHz ISM bands, which are overcrowded.
So when the auctions end the VHF bands will be full with relocated UHF channels and the UHF bands will be defragmented and auctioned off, potentially leaving only 18 MHz of spectrum for a White Space radio to operate within. This kind of bandwidth is unlikely to spark the kind of broadband access and revolution that was envisioned when the process started in 2002. And sadly, makes the unlicensed White Space spectrum a risky place to locate your M2M or other wireless application.
[i] Gary M. Epstein, Americas Spectrum Management Conference, October 24, 2012