The Broadband Debate: Is White Space the Answer?
Posted: March 16, 2010
Image courtesy of Spectrum Bridge
By John Greaves
The Federal Communications Commission has been working for months on a National Broadband Plan to transform how we use and allocate broadband spectrum. That plan will finally be presented to Congress on March 17 and may directly impact wireless providers who advocate remedying spectrum shortages by reallocating white spaces between analog TV channels for broadband use. Broadcasters believe such use would interfere with broadcast television programming. Meanwhile critics say there is no real-world data proving white spaces are the answer.
“There are some delusional technologists who believe that white space devices will compete with LTE and WiMAX, but it’s extremely unrealistic to think that white spaces will have an effective range of 30 miles with just 4 watt EIRP,” says George Ou, policy director for the think tank digital society. “There are no white space devices for consumers and even if someone comes out with a new product, it will likely be very expensive since it isn’t widely produced.”
White space proponents cite Spectrum Bridge’s white space deployment in Claudville, Va., as proof that white spaces can deliver.
Ou calls Claudville more symbolic than practical saying, “they probably could have used 5 GHz for the point-to-point backhaul connections. Claudville is using Wi-Fi for the last mile rather than white spaces because there are no white space devices on the consumer end.”
Rick Rotondo, chief marketing officer for Spectrum Bridge disputes this. “We tried using Wi-Fi at 2.4GHz, 5GHz would never have made it; 2.4 didn’t make it,” Rotondo says. “We did use Wi-Fi for the last hundred feet, not the last mile, but for the last hundred feet because there are Wi-Fi receivers built into laptops and smartphones and that’s who we wanted to be able to connect to this network,” he says.
Alan Tilles, legal counsel to numerous public safety and business radio users agrees. “If you look at Wi-Fi in the time we’ve been able to use it, you have a service that obviously has to worry about legacy. Here you have a new technology and you don’t have to worry about legacy equipment and so you can see even farther in the future and be as creative as you can be with regards to coverage area and possible services,” he says.
Google spokesperson Dan Martin says, “The white spaces are like Wi-Fi on steroids - delivering higher connection speeds across much farther distances than traditional Wi-Fi. Because of the much longer range of these spectrum signals, wireless broadband access utilizing the TV white spaces could be brought to more consumers using fewer base stations,” Martin says.
Rotondo also cites 5GHz’s poor propagation. “If you think propagation and wall penetration are bad in 2.4GHz you’re really going to hate 5GHz. It has very poor propagation characteristics in non line of sight conditions, very poor wall and ceiling penetration and it does not propagate around corners whereas TV white spaces have excellent propagation, very good building, wall and foliage penetration and it can also bend around obstacles,” Rotondo says.
However, propagation has drawbacks. “The white spaces are really not a very good choice for Wi-Fi substitution because in Wi-Fi scenarios you don’t want the signals penetrating the walls and going into your neighbor’s house or apartment,” says Richard Bennett, an Information Technology and Innovation Foundation research fellow who has contributed to Wi-Fi standards for 15 years.
Digital society’s Ou agrees. “It’s bad enough with 2.4 GHz getting interference from 8 of your adjacent neighbors who are trying to use the same channels you’re using, but getting 700 MHz interference from 50 of your neighbors would be really bad,” he says.
Where does 700MHz apply? Bennett says we have two problems, the last mile and the middle mile. “Actually the last mile breaks down into two divisions, fixed and mobile. The most challenging thing is the mobile in the last mile and these frequencies below 3GHz are the best for addressing that problem. As far as fixed goes you can take 3-6GHz and that works pretty well and then for the middle mile applications you need to get into the higher frequencies and the reason is when you’re building the middle mile you want something that behaves actually more like a wire than like a radio,” he says.
Ou says, “The solution is to eliminate the white space gaps altogether by consolidating all of the broadcast channels into a solid block with modern digital technology. This not only frees up to 180 MHz of valuable bandwidth, but it also preserves the spectrum for the broadcasters and protects them from interference. The channels that are freed up should be auctioned off to licensees for high power applications that will make it cheaper to deliver broadband to rural areas.”
Tilles asks, “Is there any reason why we cannot exploit white space to the point of having a certain portion of it be licensed, a certain portion of it unlicensed and of the licensed portion have a portion that is set aside for auctioned services and another portion that is set aside for non auctioned services like public safety?”
Rotondo thinks we should dynamically allocate spectrum on an as-needed basis. Meanwhile, Spectrum Bridge just launched another experimental white spaces deployment in North Carolina. “What’s different about the deployment in Wilmington, N.C., and New Hanover County, North Carolina, is it’s what is called a smart city application. We’re looking at specific applications that white space can be used for to help the city deliver existing services more cost effectively as well as new services using this white spaces technology.”
Tilles says, “I believe that the Wilmington experiment is exactly the type of uses that we’d like to see, which include non-consumer uses for necessary communications activities within the jurisdiction.”
As debate continues about what to do with 700MHz, many will look to the National Broadband Plan for direction.
Loading ...
I love the impassioned debate this article stimulated. However I must confess to making an error in using the terms 700MHz and White Spaces interchangeably. Dan Martin did make the statement “White Spaces are Wi Fi on steroids”, however he did not specifically name 700MHz as the portion of White Space spectrum that Google is excited about. White Spaces can actually refer to frequencies in the 54MHz and 698MHz channels as well as the 700MHz range. 700MHz was auctioned off and is not a part of the current debate. As George points out in a blog post on his own site, Claudville is actually using the 200MHz range, which I was not aware of but which makes much more sense than 700MHz would have.
Spectrum Bridge’s experimental deployments are an important step in discovering just what we can accomplish with White Spaces as is evident by the fact that the FCC mentions the Claudville and Wilmington projects by name in section 5.12 of the National Broadband Plan. The best part to me about these exchanges are that they occur in the public eye rather than taking place at scientific conferences and government policy hearings to which we as laypeople wouldn’t necessarily be privy. While I apologize for the misunderstandings created by my inaccurate use of 700MHz, I am grateful for the expansion of knowledge that came with the ensuing debates and for that I am grateful to all who participated.
The FCC apparently gave Claudville a waiver permitting higher power levels than other people can use for White Spaces applications. If this is the case - I’ve heard it, but can’t confirm it - then the Claudville system is effectively a licensed system that doesn’t have as much to worry about in terms of interference as the normal White Spaces network. One of the question marks around White Spaces is the extent to which network operators will be willing to invest in equipment to use unlicensed spectrum in which performance will always be uncertain.
Higher power limits would also enable the White Spaces middle mile to serve a larger area than the standard White Spaces system. Propagation of wireless signals is more a matter of power level than of frequency, of course. Covering a large geography with a narrow signal - white spaces channels are only 6 MHz wide, compared to 25 MHz for a Wi-Fi channel - is only practical when the area is sparsely populated. Wireless speed has more to do with channel width than any other factor.
The Claudville system doesn’t support mobility, so it will be interesting to see whether it can compete with commercial mobile networks using LTE when and if they move into the area.
LTE and WIMAX won´t smell white spaces. What will is xMax.
TV White Spaces are just a small part of the answer – as demands for spectrum continue to increase, spectrum from across all available sources must be dynamically and intelligently allocated to efficiently maximize the utilization of the finite supply of spectrum. Given the enormity of what the FCC’s Broadband plan is trying to accomplish, we must explore alternative solutions, including TV White Spaces to solve wireless communications problems through the efficient use of spectrum. Additionally, as radio technology capable of accessing white spaces under the FCC rules becomes available, network operators and consumers will have more resources to get the bandwidth they want in the location they need it. Continue to stay up to date with Spectrum Bridge’s TV White Spaces network deployments at http://www.spectrumbridge.com.