FCC’s 'Preferred' Band Plan Panned

Doug Lung

More than 200 comments were filed by the Jan. 25, 2013 deadline regarding the FCC’s Notice of Proposed Rulemaking (FCC 12-268) on “Expanding the Economic and Innovative Opportunities of Spectrum Through Incentive Auctions.” Individuals concerned that they would lose reception of favorite low-power TV stations and LPTV station owners concerned they would lose their licenses both filed comments. Also commenting were wireless mic users and manufacturers who are concerned about losing spectrum for these mics and other low-power auxiliary devices.

Adding to that list were companies involved in the development of white space wireless devices and systems who also feared spectrum loss as well as interference from wireless microphone users. Wireless carriers weighed in with concerns about interference from broadcasters and possible limits on the amount of “low-band” spectrum each one could have. Broadcasters raised issues about potential interference from other broadcasters and loss of coverage.

By now you've likely seen reports on the comments from NAB and perhaps other broadcasters. I’ll be taking a broad look at these wide-ranging comments.

One common thread through the 100 or so comments I skimmed is that none of them expressly support what appeared to be the FCC’s preferred band plan; most actively opposed it. As shown in the FCC Incentive Auction Staff Summary, it starts at Channel 51 and expands downwardly, with the wireless downlink band starting at Channel 36 and expand downwardly. TV broadcasters would use the channels in between, except for guard bands and Channel 37 spectrum. (I reported on some of the problems the National Radio Astronomy Observatory sees with the FCC's plans for Channel 37 last week and additional comments supported leaving Channel 37 as is. More on this later.)

The problems with the split band are described in the detailed technical exhibit prepared by Virginia Tech Professors Reed and Tripathi included in AT&T’s comments. The professors demonstrate that placement of television stations in the duplex gap would create significant potential for both intermodulation interference and adjacent channel interference. They also point out that harmonic signals from the lower 600 MHz band would result in harmonics that could interfere with PCS and BRS/EBS mobile downlink spectrum.

The third strike against the FCC's “lead” plan is “the FCC’s design for uplink spectrum would likely result in co-channel interference from televisions stations operating in nearby geographic areas. For example, “under the FCC’s proposal, a television station operating in 'City 1' may end up using the same 600 MHz frequencies that a mobile provider is using for uplink in nearby 'City 2.' In that situation, the television station in City 1 could cause significant interference for base stations operating in City 2, thus degrading the performance of 600 MHz mobile networks in City 2.” These concerns are echoed in comments from other wireless carriers and equipment suppliers.

I've questioned the value of the TV UHF spectrum for wireless broadband and wasn't surprised to see the AT&T exhibit and other wireless carriers comments criticizing the “36 down” downlink band proposal because antennas would have to be significantly larger to work effectively at the lower frequency. The AT&T technical exhibit notes, “Larger antennas also make it more difficult to exploit technologies that increase throughput and efficiency, such as MIMO, which requires the use of two or more antennas with a certain minimal amount of separation.” Broadcasters’ comments also rejected the idea of splitting the UHF TV band into two segments.

With this opposition, I find it hard to believe the economists at the FCC driving the auctions will select the dual band approach even if they don't understand the practical problems with it. Many of the commenters see a possibility that the FCC will obtain more than 84 MHz (14 channels) in the auction, which would result in some available spectrum below Channel 37. Even with the acknowledged problems of this lower UHF spectrum, the comments from several wireless carriers indicate they are still interested in this spectrum for applications such a “supplemental downlink,” which would likely include video services.

While interest in TDD (time domain duplex) has been growing, and some commenters feel it should be accommodated, most wireless carriers use FDD (frequency domain duplex) which requires some separation between the uplink (handset to cell site) and downlink (cell site-to-handset) frequency bands. There is general agreement that the spectrum should be auctioned in paired 5 MHz blocks. This would leave some “white space” between the two bands and also in guard bands separating high power broadcast and wireless systems. There isn't much agreement on how the duplex gap and the guard bands should be used. Wireless microphone interests want to see their devices allowed in these bands and TV band white space proponents want their use to have priority. One commenter even suggests that lower power full service or Class A TV stations could be located in the duplex gap without creating the same problems that 1,000 kW TV stations would cause and thus open up more spectrum for auction.

I was surprised to see one of the commenters supporting UHF TV band broadcast spectrum for wireless microphones was The Boeing Company. “Boeing maintains facilities across the United States where meetings, announcements and other large functions rely on unlicensed wireless microphones that operate in the TV white spaces. Boeing, like many other companies, depends on the effectiveness and flexibility of unlicensed devices and supports the Commission’s proposals to protect and expand access to spectrum for unlicensed use.” Wireless microphone manufacturers, including Audio-Technica, ask the FCC to expand the eligibility for wireless microphone licenses under Part 74. Audio-Technica also suggested created a new subsection under UWB (ultra-wideband) rules tailored to wireless microphone operations and making more frequencies available for wireless microphone use under Part 90.

There seemed to be agreement among commenters that existing Channel 37 operations should not be displaced. GE Healthcare asserted, “the Commission should not force the involuntary relocation of WMTS operations on Channel 37, as the cost of doing so would far exceed the $300 million designated for that purpose in the Spectrum Act. Even before considering the potential costs of moving the Radio Astronomy Service, and assuming the Commission could locate new frequencies, relocating WMTS operations from Channel 37 would impose substantial financial costs on healthcare facilities patients, and device makers alike, including (i) equipment replacement costs; (ii) the transition and operational costs that manufacturers would incur to engineer, develop, manufacture, and market the new systems; (iii) system disposal, installation, testing, and training costs; (iv) increased operating and maintenance costs; (v) regulatory hurdles that manufacturers would face to bring new WMTS equipment to market (including the cost of obtaining regulatory approval); and (vi) transactional and third-party expenses, such as consulting and legal fees. Moreover, relocating WMTS systems from Channel 37 would give rise to onerous intangible costs, such as disruption of hospital operations and patient safety, that are more difficult to quantify, but likely to be even more significant than the financial burdens of migrating WMTS operations to a new spectrum band.

An ex parte notice signed by AT&T, Verizon Wireless, T-Mobile, the National Association of Broadcasters, Intel and Qualcomm showed there was almost universal agreement that a “Channel 51 down” band plan with a duplex gap was preferred, guard bands would likely have to be larger than the 6 MHz proposed by the FCC to protect the wireless service from interference, and that existing operations in TV Channel 37 should remain.

The comments from NAB and some broadcasters emphasized that the coverage of TV stations not participating in the auction had to be protected in the repacking. A common theme was that existing coverage had to be protected and that interference to the specific population currently enjoying interference free reception could not exceed the current 0.5 percent de-minimis level. Obviously, if each new interferer could create up to 0.5 percent new interference the total loss of existing service would be greater. Most commenters supportive of broadcasters said the aggregate interference should not exceed one percent, although some suggested the aggregate new interference should not exceed 0.5 percent.

I may have missed it, but in the comments I reviewed I didn't see any opposition to the broadcasters' request for protection in repacking. That may appear in the reply comments, which are not due until Feb. 19, 2013, but I see this as encouraging. Even the comments from New America Foundation, a group that hasn't been a friend of broadcasters in the past, doesn't raise the repacking interference issue. It states, “These very important public interest implications of a robust market for unlicensed white space devices, networks and services make it critical for the Commission to adopt priorities and policies for TV band repacking and relocation intended to optimize both broadcast TV and the aggregate utility of unlicensed access to white space spectrum.” It is surprising that after broadcasters feared white space devices on unused TV channels a few years ago, broadcasters and white space proponents now share a common goal in preserving spectrum for broadcasting and for the “white space” necessary to keep TV stations from interfering with each other.

Comments from two companies provided insight into how difficult, time-consuming and expensive it would be to repack a large number of broadcasters. Sprint Nextel had recent experience with that during the 2 GHz location. Harris Corporation, a major manufacturer of equipment for radio and TV, explained the equipment and labor necessary to change a TV station's channel. It also provided some guidance on what the FCC should do with the low VHF spectrum--give channels 5 and 6 to FM broadcasters and reserve Channels 2, 3, and 4 for low-power TV stations. Low-band VHF full-service TV stations would move to high-band VHF allocations.

This is a very short summary of hundreds of pages of comments with a range of opinions. As a former South Florida resident and supporter of WLRN, I especially appreciated the provocative comments from The School Board of Miami-Dade County, Fla. I'm interested in seeing what reply comments they attract.

To view all the comments, use the FCC Electronic Comment Filing System Search and enter “12-268” in the “Proceeding” box. Groups and individuals are now working on their reply comments due Feb. 19. After that the FCC will likely release a Report and Order with a discussion of the comment and its decisions on at least some of the issues raised in the NPRM and the responses they generated.

Doug Lung

Doug Lung is one of America's foremost authorities on broadcast RF technology. As vice president of Broadcast Technology for NBCUniversal Local, H. Douglas Lung leads NBC and Telemundo-owned stations’ RF and transmission affairs, including microwave, radars, satellite uplinks, and FCC technical filings. Beginning his career in 1976 at KSCI in Los Angeles, Lung has nearly 50 years of experience in broadcast television engineering. Beginning in 1985, he led the engineering department for what was to become the Telemundo network and station group, assisting in the design, construction and installation of the company’s broadcast and cable facilities. Other projects include work on the launch of Hawaii’s first UHF TV station, the rollout and testing of the ATSC mobile-handheld standard, and software development related to the incentive auction TV spectrum repack. A longtime columnist for TV Technology, Doug is also a regular contributor to IEEE Broadcast Technology. He is the recipient of the 2023 NAB Television Engineering Award. He also received a Tech Leadership Award from TV Tech publisher Future plc in 2021 and is a member of the IEEE Broadcast Technology Society and the Society of Broadcast Engineers.