Failure to conduct engineering studies of potential co- and adjacent-channel interference stemming from a repack of TV spectrum and the repurposing of different amounts of spectrum in different markets — known as spectrum “variability” — threatens to derail FCC efforts to free up TV spectrum for the wireless industry and maximize auction proceeds.
Those are among most important conclusions of reply comments filed June 28 by NAB with the Federal Communications Commission.
The 10-page filing submitted by NAB spectrum point man Rick Kaplan draws on comments filed by wireless companies, including AT&T and Verizon, and even smartphone maker Research In Motion as well as the association's own spectrum expertise to make the case that the commission has not done the necessary work to understand the likely interference resulting from variable use of spectrum from market to market. Before proceeding with a spectrum auction and repack, the FCC must engage in what the comments describe as a rigorous "study of the effect of variability on interference between broadcasters and wireless operators."
Branding interference as “a threshold issue,” the NAB comments drew an analogy between the repack and the agency’s LightSquared proceeding. “If the Commission does not study and address it [interference], then the law will not allow the Commission to employ it [variability],” the comments said. A “rigorous look” at the interference issue “might well demonstrate that the costs of variability outweigh its perceived benefits.”
Drawing on comments filed by AT&T, NAB noted that the telecommunications giant said it has begun studying the issue of co-channel interference from TV transmissions to wireless base station receivers and as preliminarily found “that separation distances could significantly limit the ability to offer different amounts of spectrum at auction” on a market by market basis.
NAB quoted comments from Verizon pointing out that “[a]bsent natural barriers between markets, such as mountains that mitigate co-channel interference, geographic separation zones of 200km-400km would likely be required to mitigate interference from broadcaster transmitters into wireless base stations.”
NAB also urged the commission to adopt a nationwide spectrum-use plan as an alternative to market variability.
The association concluded that consideration of interference issues “can no longer be treated as an afterthought because, if left unaddressed, it threatens to at least delay the auction, if not undermine its effectiveness.”