L.A. TV stations show broadcast channel sharing for 600 MHz auction is possible

The CTIA and two TV stations in Los Angeles finished a pilot to test whether stations can share the same broadcast spectrum and concluded that it is technically possible. The tests were designed to show other broadcast stations that channel sharing can be an alternative for stations that want to give up their spectrum as part of next year's FCC incentive auctions of 600 MHz broadcast spectrum.

However, a report from the CTIA and representatives from the two stations, KLCS and KJLA, warned that there were limitations and still many questions that need to be answered by both broadcasters and the FCC. Further, even though the stations have finished their tests, neither is willing at this point to commit to relinquishing their spectrum and participate in the auction.

"From the data we have gathered, it is clear that channel sharing is possible," the report concludes. "The technology exists that makes it viable for two compatible broadcasters to do so. Whether two entities can successfully combine their required program streams and business models can only be answered by the stations interested in sharing."

Under the FCC's proposed auction rules, broadcasters will submit bids to relinquish their 600 MHz pieces of spectrum in a reverse auction where the FCC will pay them. The FCC is also contemplating having unlicensed wireless use in the guard bands between spectrum blocks.

The process is voluntary for broadcasters, but many worry that broadcasters might not give up their spectrum based on their previous resistance to the auctions and uncertainty over how much money they will ultimately receive, as well as how their operations will be affected by giving up their spectrum. That last concern is what the CTIA was trying to assuage with the pilot by showing that broadcasters can share channels with others if they give up their spectrum.

After broadcasters give up their spectrum, it will be "repacked" so that broadcasters that do not give up their spectrum can stay on the air. Then the FCC will conduct a traditional "forward" auction in which wireless carriers will bid for the freed spectrum. Still, an enormous number of technical rules need to be worked out; the rules are expected to be released by the FCC in May.

During the pilot, which the FCC approved in February, KLCS and KJLA conducted a series of tests that included KLCS "hosting" KJLA's content and transmitting a shared stream that combined the two stations' primary and multicast content. The stations also looked at combining a variety of HD and SD video feeds to confirm the feasibility and technical limits of channel sharing between two unaffiliated broadcast stations.

KLCS reaches a potential viewing audience of over 5 million households in Los Angeles, Orange, San Bernardino, Riverside, Ventura, and San Diego Counties. KJLA is carried in Los Angeles and surrounding counties on approximately 2.8 million cable homes and 2 million DBS satellite homes, in addition to operating over the air.

CTIA has said that to test the viability of the sharing technology, it wanted to work with broadcast TV stations in a large city where there is high demand for spectrum. If the incentive auctions are to succeed, broadcasters in major metropolitan areas will need to give up their spectrum, since carriers need airwaves more in major markets than in rural areas.

The tests were highly technical and produced equally arcane results. Some of the results concluded that on a virtual level, all the TVs and tuners tested were able to receive and correctly parse all the required information. However, the results suggested that "careful thought must be put into the transition, whether for repacking or sharing, by the FCC and broadcasters to find a solution that will ensure a positive viewer experience."

The tests also showed that it is technically feasible for two 720p HD streams to be combined into a single Advanced Television System Committee ("ATSC") channel. Stations that want to do channel sharing need to consider a number of factors though, including whether to use fixed or dynamically allocated bitstreams between the stations; the relative "digital complexity" of the video content to be transmitted by the stations; how to govern the division of the bitstream based on those requirements; and how to monitor and manage any agreement reached on sharing of the bitstream itself.

Further, the report and testing found that bandwidth management (or allocating the bitstream among a variety of services, metadata, video and audio) must be determined upfront for channel sharing to work properly.

Alan Popkin, director of TV engineering at KLCS, told FierceWireless he had no idea whether or not the sharing was going to work. "I like to think that just about anything you can dream up can be accomplished, assuming you throw the right technology at the problem," he said. "We weren't sure the right technology existed." He said he was "amazed" with the results.

While the pilot showed channel sharing is technically possible, it's not clear how much it will cost individual stations to do it. Popkin said that most stations will need to buy new encoders within the next few years anyway, which should lessen the burden. However, he said before even figuring out the cost, a stations must determine if their systems are compatible with a nearby station in terms of their broadcasting material, channel count and business models.

"If the business model doesn't work, who cares about the technology?" he said.

Both Popkin and Eddie Hernandez, director of operations and engineering at KJLA, emphasized that neither station has committed to participating in the incentive auctions. "We embraced this opportunity to do this test for the simple fact that any knowledge is going to help us and our management going forward," Hernandez said.

The FCC still has a long way to go to win broadcasters over. Rick Kaplan, executive vice president for strategic planning for the National Association of Broadcasters, recently said that it's too early to say whether TV broadcasters will widely support the incentive auctions. "It is my hope that broadcasters closely study the channel sharing pilot project report as they consider the once-in-a-lifetime opportunity offered by the upcoming incentive auction," FCC Chairman Tom Wheeler said in a statement.

For more:
- see this report (PDF)
- see this CTIA release

Related Articles:
TV broadcasters remain wary of 600 MHz incentive auction
FCC's Wheeler lays out vision for 3.5 GHz band, incentive auctions
FCC to issue report on 600 MHz incentive auction structure in the spring
FCC approves broadcast spectrum sharing pilot for L.A. TV stations
CTIA, L.A. TV stations launch pilot to demonstrate broadcast spectrum sharing

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