Wireless companies in spectrum adjacent to TV channel 51 want their neighbors to vamoose.

In the Old West, even the vast wide open spaces were not vast enough and wide enough for everybody. Farmers and cattle ranchers fought over scarce resources, like water and grazing rights.   These conflicts were known as range wars.

The tradition lives on, but the turf in dispute today is spectrum, particularly TV channel 51. The wireless companies want to ease out the TV broadcasters, who may want to stay put. Better hunker down; the legal papers are going to fly.

The dispute is a by-product of the digital TV transition a few years ago. Digital technology allowed the geographic repacking of TV stations into fewer channels than before. That freed up 108 MHz of spectrum in the 700 MHz band, part of which the FCC auctioned off to wireless broadband providers for almost $20 billion. Even here in Washington, that counts as real money. The government got the cash; the broadcasters got to quadruple their video capacity; and the wireless companies got more bandwidth, over which customers could download more videos of cats riding on vacuum cleaners.

Now the happy honeymoon is over. Reality has settled in. The domestic-bickering phase has begun.

The immediate issue is TV channel 51, which (after the transition) is the highest TV channel at the highest frequency. Just above it in the spectrum, where channel 52 used to be, is the lower portion of the wireless 700 MHz band, known to the cognoscenti as A Block. But channel 51 and A Block are on different frequencies, right? So there should be no conflict.

That sounds logical, but it’s wrong.

The problem lies in receiver design. Channel 51 covers 692-698 MHz. Ideally a TV set tuned to channel 51 would receive everything in that range, and nothing above or below. Sadly, though, that is not possible.  You can build a receiver that comes pretty close, but it would add more cost to the TV than a consumer wants to pay. A real-world TV receives some signal above and below the channel it is tuned to. In particular, a TV tuned to channel 51 will pick up some signal from above channel 51, in wireless A Block. The TV does not show the cat on the vacuum cleaner, but the wireless signal can degrade or even block the TV reception. The reverse is likewise true: reception on an A Block mobile wireless mobile device can be impaired by a nearby TV station on channel 51.

Of course, that last irks the wireless companies. Even worse, from their standpoint, is their legal obligation to protect channel 51 TV reception. The strength of the wireless signal must not exceed that of the TV signal by more than a certain amount within the station’s service contour, which for this purpose is anything within 55 miles of the station.

Two factors make compliance difficult. First, some Block A devices are mobile handsets that can inadvertently stray into the 55-mile zone and put out more power than is allowed. This is hard to prevent. Second, although the viewing public thinks of TV stations as being relatively permanent, in fact they come and go and change their channels (all subject to FCC consent). So even if an A block wireless company can work around all the stations currently operating on channel 51, another one can pop up at any time.

The wireless company trade associations have filed a petition with the FCC to complain about these problems and request relief. The petition opens with several pages on the importance of wireless broadband (no mention of the cats). Then come three requests:

  1. change the rules to foreclose all future TV licensing on channel 51;
  2. in the meantime, freeze all future and pending TV applications to operate in channel 51; and
  3. streamline procedures for facilitating “voluntary efforts” to relocate existing channel 51 licensees to other channels.

To be sure, the problems facing A Block licensees should not be a surprise. The companies that bid on that spectrum knew they would have to protect channel 51 TV stations, including later arrivals, and they knew the risk of incoming interference from TV operations. They bought the spectrum anyway, “as is.” Yet now they want the FCC to control the number of channel 51s they must deal with. They also hint that people might seek channel 51 licenses “to exploit opportunities for personal gain” at the expense of an A Block licensee – in other words, to deliberately make trouble for a wireless company, with an offer to go away if paid enough money. On the other hand, the “voluntary efforts” mentioned in item 3 above appear to involve payoffs to existing channel 51 licensees from willing wireless A Block licensees.

The wireless companies could have solved their problem, in principle, by leaving the lower part of A Block vacant as a guard band. That would cost a lot of money. Instead, despite not having paid for it, they want the 6 MHz of channel 51 to be vacant.

The FCC has not yet put out the request for comment. We will let you know if and when that happens.