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While the court wrangling is going on, I think those who believe they have "won" the right to use this spectrum without a license will begin to find out just how little of it they really have available in urban areas.

TV White Space-Again

Thursday, March 05, 2009

As predicted, both the National Association of Broadcasters (NAB) and the Association of Maximum Service Television (MSTV) have filed lawsuits against the FCC for its new TV White Space rulemaking. You might recall that in November of last year the FCC voted to permit unlicensed use of the space between TV stations in each area of the country for broadband services.


The service was supposed to become available in June of this year, but this suit could delay that date. Broadcasters are claiming that this new use of the TV spectrum will have a direct adverse impact on MSTV's and NAB's members because it will allow harmful interference with reception of their broadcast signals. This is based on the fact most of today's TV receivers are very poor receivers with little if any protection from adjacent channel interference, which is why the FCC required TV stations to be staggered across the TV band to begin with, leaving this white space between stations to avoid such interference.


So far, nothing has been heard from the makers of wireless microphones that already share this spectrum, or from public safety agencies in major cities such as Los Angeles, San Francisco, Chicago, and New York that have been using vacant TV channels for additional spectrum for their first responder systems.


The proponents of unlicensed TV spectrum (those who won) claim that it will be a boon  to providing broadband services in both urban and rural environments and that it will push the envelope of technology advances. It might, in fact, be a valuable resource in rural America where TV stations are few and far between. However, though TV White Space will cover more area than typical 2.4-GHz and 5.8-GHz Wi-Fi systems because it is lower in frequency, the power limits are pretty low when compared to existing wireless broadband systems including CDMA, UMTS, and WiMAX. "Pushing the envelope of technology development" is a catch phrase that is easy to throw around, but I have seen no indication that opening up this band will promote new technology except for meeting some pretty stiff requirements for fixed, nomadic, and mobile devices.


While the court wrangling is going on, I think those who believe they have "won" the right to use this spectrum without a license will begin to find out just how little of it they really have available in urban areas. According to the FCC rules, putting devices into service will be a daunting task. This and the fact that this is unlicensed spectrum leads me to believe that anyone who reads the rules will have one of two reactions: They are too complex with lots of restrictions, or damn the rules, I'll do what I want.


To see how much spectrum is available in each city, go to  which is run by Spectrum Bridge. This is not yet a complete list but, for example, it indicates that only a single 6-MHz block of spectrum is available in the San Francisco area. Basically, this means that there will be no fixed, outdoor devices permitted, only nomadic and mobile devices that will be running at a maximum power level of 40 Milliwatts (Mw). To run fixed stations with a power output of 1 watt, with antenna gain providing a total output of 4 watts of Effective Radiated Power (ERP), these stations would have to operate in a second channel adjacent to a TV station. The FCC wording reads like this:


"All Devices. All unlicensed TV band fixed and personal/portable TV band devices will be permitted to operate on TV channels 21-51, excluding channel 37. In addition, fixed TVBDs that only communicate with other fixed TVBDs will be permitted to operate on channels 2 and 5-20, except that they must avoid operation on channels used by private land mobile radio service (PLMRS), i.e., public safety, and commercial mobile radio service operations on channels in certain markets and areas adjacent to them. Also, in individual markets where there are Private Land Mobile Radio Service or Commercial Mobile Radio Service (PLMRS/CMRS) operations on channels 14-20, two channels in the range 21-51 will be reserved for operation by wireless microphones such that TVBDs will not be permitted on those channels. This plan for channel use is consistent with the requests of the various white space proponents and would reserve channels for a "safe harbor" for operation of wireless microphones and ensure protection of the public safety and other land mobile services that use channels 14-20. At this time, we are only permitting fixed TVBDs to operate on channels not that are not immediately next to (first adjacent on either side of) the channel of a TV station; personal portable devices will be allowed to operate on first adjacent channels to a TV station subject to the power limitation indicated above. All unlicensed TV band devices will be required to limit their out-of-band emissions in the first adjacent channel to a level 55 dB below the power level in the channel they occupy, as measured in a 100 kHz bandwidth. In addition, all TVBDs will be required to comply with a more stringent out-of-band emissions band at the edges of channels 36 and 38 that are adjacent to channel 37 in order to protect medical telemetry devices on that channel 37. Fixed devices will also be required to periodically transmit a signal with their identification when they are operating. This will facilitate identification of sources of interference. The database system for fixed stations and personal/portable devices with geo-location and database access capability will be managed by a database manager or managers selected by our Office of Engineering and Technology. The specific provisions of this plan are presented below."


So even if the broadcasters are not successful in their quest to have the rules overturned, the present rules will make it very difficult for anyone to operate a base system with an outdoor antenna within a major metro area since, according to the database, most of these cities only have 6-MHz blocks of white space and not the 18 MHz it would take for a base station. I say 18 MHz because the rules clearly state that no base station will be permitted adjacent to a TV station, so ONLY areas where there is a 6-MHz buffer both above and below TV stations means that in 18 MHz of white space, the middle 6 MHz could be used for base stations. Further, if the mobile units were operating on the adjacent channels they would have to run at a power level of 40 Mw versus 100 Mw if they were in the clear.


As mentioned, my fear is that since the rules are so convoluted, and the FCC field offices have basically been gutted of engineers and enforcement personnel, there will be some who simply go ahead and put devices on the air without following the rules, causing severe interference to their neighbors' TV sets. With no licenses required, and no enforcement, how will the FCC even begin to make sure the rules are followed? What recourse will homeowners and apartment dwellers have if there is a problem? If they call their local FCC office, they will get the brush-off-I know this from personal experience. It took more than three months of constant calls and pushing the FCC with recorded tapes of fisherman off the coast of California using amateur radio frequencies to talk to each other to get the FCC to intercede. And today there are many two-way radio systems that have never been licensed or for which licenses have expired that are interfering with those who follow the rules.


I do believe white space spectrum is a valuable resource and should be used where appropriate, but there is a better way to handle it. It should be managed or licensed so a specific person or company is ultimately responsible for minimizing interference and any costs associated with correcting problems. My November 6 column in FierceWireless was entitled, "White Spaces Decision Will Haunt the FCC," and I am sticking by both what I wrote there and the points I have made here.


Andrew M. Seybold

COMMENTS: This is an archived post. Commenting is no longer available.

Peter Moncure - 03/05/2009 13:36:35

Several points:
1) I have analyzed the Spectrum Bridge site, and while it is fairly accurate in showing where TVBD's are precluded, it cannot be used to show where they may be sited. There is no spectrum at all in almost all major markets, including SF.
2) To counter the "damn the torpedoes" approach, the TVBDs are required to "phone home" to the new database(s) at least once daily, and if found not in compliance they will be disabled. Sure, anyone can make such a device fairly easily, but the possibility of FCC sanctions will deter any manufacturer from making a unit which can be easily modified to circumvent the intent of the Rule.
3) I agree with your main thrust. BPL and UHF TV white space seem from most accounts to be little understood by those pushing the technology. Or maybe they DO understand it and are playing Russian Roulette with our spectrum and tax dollars? Or maybe it is the lawyers or their unwitting shills?
4) I have been considering, on behalf of RadioSoft, applying to be a TVBD database provider, and have been contacted by many others for advice about how to become one (yes, I explain to them I'd be competing!). Right now however, I don't see a commercial case for its implementation. Can you spell D-Block? Where would Google roll out its testbed? Not in Silicon Valley, there's no spectrum there. If they move to Eureka, sure but the inevitable requirements of rural densities and competition with the DSL providers makes that unlikely to ever turn a profit.

Face it: rural broadband and rural 700 Mhz public safety communications are too expensive to be commercialized without someone's taxes or subsidies.

Andrew Seybold - 03/05/2009 13:53:19

Peter--thanks for your comments--and yes I agree with you that those who went after this spectrum did not think about what they were doing--and as far at the TVDB's having to "talk" back once a day, what makes you sure that somene will not build one that does not and is just on the air--Bi-Directional Amps are illegal unless licensed by the spectrum holder but look on the Internet and see how many people are selling them.
Thanks again

dave maples - 03/05/2009 16:30:20

Don't want to beat a drum here, but what happens when multiple TV white space devices start transmitting and impinging on the front end of DTV receivers and converter boxes? Can you say receiver-generated IM? In suburbia, it should pretty well do a number on OTA TV reception.