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Making use of white space is not a new idea. Many two-way radio systems, including many police and fire systems, occupy spectrum that is not used in their city for over-the-air TV

A Missed Opportunity for Whom?

Monday, May 26, 2008

Google is at is again. It had an impact on the 700-MHz auction C block, won by Verizon Wireless, it has thrown its hat into the ring with Clearwire's new partnership with Sprint, Intel and some cable companies, and now it is after white space spectrum and going after it big time, hitting both Congress and the FCC. Google co-founder Larry Page seems to be the point person for this latest volley and he feels confident he will be successful.


Let's start at the beginning. What is white space? TV stations that transmit over the air are assigned 6 MHz of spectrum and other stations in the same city are offset by at least one if not more channels. This was done originally because the receivers in most TV sets could not filter out the next channel over, so if there was a station on both channel 3 and 4 in the same area, chances are most of the TV receivers could not see or hear either because they would cause interference in the receiver.


So white space is the gap left between TV stations in each city and it varies from city to city and town to town. It is a little more involved than that (and confusing) because there are some built-in gaps in the TV spectrum allocations. For example, between Channels 6 and 7 there is almost 92 MHz that are used for other services including aircraft and FM broadcast. There is also a gap between channels 13 and 14 of more than 260 MHz and, again, there are other services in between them. Channels 2-13 used to be called VHF-TV channels and channels 14 and above were called UHF-TV channels. In the old days of TVs, you needed two separate antennas to receive VHF and UHF signals. You could have both a channel 6 and 7 in the same city since there was a built-in gap, and you could have both a channel 13 and 14 since there was a built-in gap, but you could not have a channel 3 and 4, 7 and 8, or 14 and 15 because they are right next to each other.


Making use of white space is not a new idea. Many two-way radio systems, including many police and fire systems, occupy spectrum that is not used in their city for over-the-air TV. For example, in Los Angeles, County Fire and Sheriffs operate on what would be channels 16 and 17, while the City uses channels 20 and 21. The nearest TV channels used for over-the-air broadcasts in Los Angeles are channel 18 in Long Beach and channel 22 in Los Angeles. One important point here is that since the TV stations, first responders and two-way radio users are licensed by the FCC, if there is interference it is fairly easy to determine who is causing the problem and work on a resolution. In an unlicensed white space world, this would not be the case.


The advocates for white space use are being challenged by the National Association of Broadcasters and a number of other organizations. Google and others think this is because the NAB wants to hold onto the spectrum. The NAB has already lost the upper channels to new wireless voice and data services because the spectrum was auctioned earlier this year.


The forces behind unlicensed white space access claim their equipment can "sniff" out TV channels that are in use and use only white space that is not occupied, thus everyone can co-exist. I guess they don't understand the issue with cable TV operators. Yes, cable TV signals travel over coax or fiber, BUT they use virtually all the available spectrum, including the same spectrum as the TV channels, and they do not have gaps or white space between their channels. The cable companies feed radio frequency energy down the coax and if you look at a list of channels they use, you will find that the spectrum starts very low and goes almost continuously well beyond where white space proponents want to settle.


Why does this matter? In one of the lists of "available" white space I have seen, unlicensed broadband would be used on channel 29 since there is no channel 29 TV broadcaster in that city. However, there is a cable TV company that IS using channel 29 (cable TV channel 80) and it is very possible that a white space device could easily interfere with someone's TV even if it was connected directly to a cable TV feed. Someone using an unlicensed white space broadband device in an apartment complex could wreak havoc with a number of different TV sets and there would be no way to determine the cause of the interference. Unlicensed means unregistered, which means unless you spend a lot of time with some very expensive equipment to "sniff out" the unit, there are no records as to who might be using it for what.


I am not necessarily against using empty TV space for broadband data services; much of this spectrum is ideal for much longer distances than Wi-Fi or even on the Clearwire WiMAX system. Speaking of which, I guess the $500 million invested by Google in the new Clearwire doesn't matter if it wants the FCC to authorize unlicensed white space usage and compete with Clearwire. $500 million to Google is about the same as my buying a $1 lottery ticket.


The issues with white space usage need to be studied further. Perhaps there is a way for someone to be licensed or responsible for equipment in a given city so that as problems arise, and they will, they can be dealt with in a timely fashion without costing anyone too much money. If Google or anyone else thinks the FCC enforcement branch will be able to do anything about interference complaints, they had better think again. This branch of the FCC has been pared to the bone and only has time to work on major issues-and then not always in a timely fashion.


By the way, cable companies can also cause interference to white space receivers. Remember that cable companies are pumping radio frequencies down their coax and some of the cable plants are old. There is always some leakage, it cannot be helped. When you look further at cable companies' frequencies, you will see that they offset their channels that overlap with the FAA air traffic communications systems in order to minimize any potential interference. If the FAA is worried about cable operators' potential for interfering with aircraft communications, I am also concerned that they could interfere with white space devices. And even though they might be unlicensed, if they don't work people are going to be upset.


Remember muni-Wi-Fi? Some cities were giving it away for free, yet when it did not work, people did not remind themselves it was free and complained that their service had stopped working. And since it was free and unlicensed, no one had either the motivation or the funds to get it working again and many muni systems have died under their own weight.


There is a lot of valuable spectrum sitting idle between TV channels and each year fewer people are watching TV using an antenna (at least 80% of viewers are using cable or satellite systems to pull in their signals). But that does not mean those who want to turn white space into unlicensed spectrum have the right to cause interference to others and, perhaps, have people who bought the equipment in good faith find out it does not work as advertised.


Licenses are not only about paying money for spectrum, they are about being able to identify who is causing interference so it can be corrected. Licenses are not only about big telecommunications companies providing services for others and, according to those from the Internet community, gouging us for doing so, they are about providing a level of service measured using the rule of the five 9s-a reliability factor of 99.999%. I am sure Google's technical staff is using the same type of measurement system for its own servers and networks, so why should it expect consumers to settle for something less?


Andrew M. Seybold



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

Jimmy CrackCorn - 05/27/2008 05:29:53

Dude, why are you so anti-google? They be pushing the envelope so I can get me some free cell phone service. Open access! Bring down the walls! You always sound like a shill for big telco!

Daniel Callahan - 05/27/2008 16:18:24

Would you be in favor of a solution that required registration, so interference issues could be tracked down and resolved, even if there were no registration costs? Is your issue with "free riders"? or lack of accountability?

Andrew Seybold - 05/27/2008 20:04:43

Daniel--not a bad idea, but what if I bought one, registered its location where I lived and then decided to take it to work and did not bother notifying anyone? I don't think it would take very long to have a problem.
Remember the CB band? Free licenses, then fee licenses then no licenses as the FCC gave up and walked away?
Today you can buy family radios (FMR) which in addition to the unlicensed channels also include the GMRS channels which need to be licensed to use--and the devices all come with a license form to fill out--how many of these devices to you think ever get licensed? And by the way, how many are being used outside of the U.S. where the frequencies are NOT set aside for FMR radios?

Like I said, I don't have a problem with tryiing to utilize this spectrum in some way, but I do believe that there needs to be a way to track down those who might be interfering with others and not even know it.