Don't Tread on Broadcast

MSTV challenges FCC's unlicensed devices proposal


The FCC's late-May proposal to allow the use of unlicensed wireless devices in the TV broadcast spectrum has prompted broadcast lobbyists to fight back.

"By this Notice, we propose to allow unlicensed radio transmitters to operate in the broadcast television spectrum at locations where that spectrum is not being used," read the FCC's Notice of Proposed Rulemaking.

Representing over-the-air television broadcasters, the Association for Maximum Service Television (MSTV) was quick to file a Request for Clarification, asking for details.

MSTV's senior vice president, Victor Tawil said the organization's key objection is to rushing unlicensed wireless devices into the television broadcast spectrum "Once they're out there, there's no way to call them back," he said.

In its NPRM, the commission didn't specify exactly what devices could end up operating on vacant channels in the TV band.

The Consumer Electronics Association includes the following devices in that category-cordless phones, garage door openers, wireless routers (Wi-Fi), remote-control toys, walkie-talkies, baby monitors, home security systems and keyless entry systems for cars.

However, comments accompanying the NPRM by FCC Chairman Michael Powell and other commissioners focused on wireless broadband deployment, which would include Wi-Fi and other future wireless data technologies.

The commission noted that due to the physics of signal propagation, transmissions in the TV band could travel farther and better penetrate buildings than transmissions in the spectrum where existing unlicensed wireless broadband operations are permitted.

MSTV's filing doesn't reject out-of-hand allowing such devices to operate in the TV broadcast spectrum, but the organization wants to do exhaustive testing of the proposed technical parameters to assure there will be no interference with over-the-air television broadcast signals.

The association asked for several technical specifications to be clarified so it could effectively begin its testing.


What concerns MSTV is the difficulty of getting the genie back in the bottle, so to speak, once the devices in question hit the market.

"There's no enforcement mechanism, especially for these devices," Tawil said.

"There would probably be portable computer devices, WiFi systems, individual portable units. You can't chase everybody who has one of these units and tell them they've got to shut them off."

"We're somewhat surprised about the [MSTV] filing," said FCC Office of Engineering and Technology associate legal chief, Bruce Romano.

"We've had discussions and have offered to have other discussions with MSTV on this issue, and certainly we wanted to assure folks," he said. "Other people didn't have a high degree of problems understanding what was being said in the item."

Romano indicated that by the time this issue of TV Technology is in the mail, the commission will have responded to MSTV.

Key to successfully allowing wireless devices to operate in the TV spectrum is assuring that the devices operate only in unused channels, which vary market to market. For example, Channel 6 is not used by a station in Pittsburgh, but assigned to a Philadelphia station.

And the commission realizes channel assignment is not a static situation.

"A lot of the concern was that low-power television stations were going to be changing frequencies coming on the air, and we've got the DTV transition going on, changing channels," Romano said."[The challenge is] how can we ensure that these devices don't cause interference."

The answer, according to the NPRM, is for the devices to check a channel's availability not by actually testing to see if a signal is present, but by accessing an up-to-date database that would indicate whether a licensed TV broadcaster occupied it or not.

MSTV's filing raises highly technical questions about operating bandwidth and channelization, operation within single or multiple channels, modulation type and signal level.


But the organization has more basic questions as well.

"The fact is, you don't know what kind of devices will be permitted in that band," Tawil said. "They haven't defined what is allowed, what type of services that they intend to allow there, like 802.11 or 802.16."

He said that unanticipated problems have previously occurred when RF devices have been allowed to operate in television broadcast spectrum. In particular, there was a case where early digital broadcast signals interfered with heart monitors in Texas in 1998.

"The heart monitors were used on Channel 7," he said. "When DTV was fired up [on Channel 7], it caused interference to them."

And Tawil said interference from these devices might be more troublesome for DTV.

"The manifestation of interference in digital is more severe, because you have a picture and all of a sudden it freezes, or it gets blocked," he said. "In analog, the picture would be degraded, but might be degraded gracefully. It might take less signal to affect the analog signal, but it wouldn't shut off as a digital signal would."

The CEA, which represents not only manufacturers of the unlicensed wireless devices but of makers of television receivers as well, weighed in Solomon-style on the issue.

"I know from talking with the FCC, they see opportunity for the use of this unused spectrum, as long as there will be no interference with the broadcast; therefore, they see opportunity for devices that are unlicensed to use that band," said CEA Director of Government Affairs Veronica O'Connell.

That association's 2002 survey shows more than $2 billion in sales of unlicensed wireless devices on an accelerating growth curve. This leaves little question that such devices will need new spectrum in which to operate. MSTV wants to make certain the new devices are rigorously tested before they are put in the untraceable hands of the consumers.

The period for public comment on the NPRM runs through Aug. 8.