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Cable/Video

Cable Worried About 'White Space' Tech

The National Cable & Telecommunications Association (NCTA) has fired off a letter to the Federal Communications Commission (FCC) declaring that proposals to use licensed and unlicensed broadcast "white spaces" to deliver broadband services could cause "harmful interference" and impair cable services.

Several big dogs, including Google (Nasdaq: GOOG), Dell Technologies (Nasdaq: DELL), Microsoft Corp. (Nasdaq: MSFT), and Intel Corp. (Nasdaq: INTC), are salivating over the possibility of putting broadband services in white spaces, the unused broadcast spectrum expected to emerge after broadcasters relinquish their analog spectrum in the February 2009 digital TV transition.

For instance, the technology could be used to offer high-speed wireless services to rural areas that aren't reached by cable operators or telcos.

To plead its case and explain the technology, Google recently launched the "Free The Airwaves" campaign, referring to white spaces as "WiFi on steroids."

But the NCTA sees three potential problems: interference with TV receivers, interference with headends, and interference from fixed-line use.

Those concerns aren't exactly new. Earlier FCC tests showed that some prototype white-space devices impaired the performance of some digital cable-ready (DCR) televisions, which use CableCARD interfaces to authorize digital cable services without a set-top. (See 'White Space' Worries .)

The FCC's Office of Engineering and Technology hasn’t released the results of a new round of tests on white-space device prototypes that got underway in mid-July. Results will certainly factor into whether the FCC will permit the use of those devices on unlicensed spectrum or if any special rules will need to be applied.

Although broadband services on white spaces certainly would clash with cable's own broadband services, the NCTA claims to be supportive of the technology. However, it argues that there hasn't been enough attention given to the "likelihood that unlicensed TV band devices, as currently proposed, will interfere with cable service."

Citing FCC lab results and NCTA's own technical analysis of those results, the cable pressure group says unlicensed devices operating as low as 4.3 mW can cause interference to cable digital TV reception at a distance of two meters. To put things in perspective, unlicensed TV band devices being considered today operate at 100 mW -- more than 20 times that power level.

"Television receivers, both analog and digital, are simply incapable, as the FCC's tests have shown, of shielding the TV picture from such interference," the NCTA claims, noting that degradation problems are more pronounced in apartments and other multi-dwelling units where people share common walls.

Cable systems, the NCTA points out, "have no 'white spaces,' " because they deliver services on all the channels in the broadcast TV band.

"The lack of vacant channels on cable poses unique risks of interference to television viewing on any channel where high-powered TV band devices operate nearby." Wherever interference occurs, "broadcast programming will be wiped out for the entire community served by that cable system," the letter warns.

However, should the FCC go ahead with authorizing unlicensed TV band devices, the NCTA suggests several rules that would help to avoid interference. Among them: prohibit operations, at a minimum, on channels 2 to 4, so cable can solve direct pickup (DPU) interference when it arises through the use of "external, well-shielded set-top converters;" and prohibit the operation of fixed devices in VHF channels due, in part, to the increased potential for DPU interference.

The NCTA also took issue with proposals to use licensed, fixed spectrum. Using the example of a proposal from FiberTower Corp. and the Rural Telecommunications Group to deliver services in rural communities, the cable pressure group claims that cable-ready sets could be impaired "from distances as far as three miles away."

— Jeff Baumgartner, Site Editor, Cable Digital News

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