The White Space Landscape Is Still Forming

Carl Weinschenk
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Top 10 Wireless Predictions for 2011

There are two important things to know about the current status of white space development. One is that the FCC and Congress are deciding on issues that will significantly impact - and potentially reduce - the potential for the technology. The other is that even as this comes to pass, the science that is being pioneered will remain a big deal. It potentially will help alleviate the coming mobile bandwidth crunch that virtually all experts suggest is bearing down on a world afloat in tablets, smartphones and legacy mobile devices.

White space is the name given to the spectrum that has become available as the FCC has relocated many broadcasters from lower parts of the spectrum. The basic game plan is to make this spectrum available to wireless providers and create what many refer to as "Wi-Fi on steroids."

This bandwidth is very good, which was why it was used for broadcasting in the first place. Two of its main attributes - the ability to cover long distances and to permeate structures - make it perfect for the services envisioned by white space companies. That is one reason why companies such as Dell, Microsoft and Google are involved.

Two other interrelated points make white space difficult and, ultimately, exciting: Different spectrum is vacant in different parts of the country. Thus, the availability of white space in New York City is different than in Big Water, Utah or Fair Haven, Vt. The corollary is that this is a rare instance in telecommunications in which the rural locales have the advantage over the cities. The airwaves in the Big Apple are as jammed with broadcast signals as the Long Island Expressway at 6 p.m. on a Friday. Thus, white space spectrum is far more abundant in the countryside.

Whether the city or the country has the advantage begs a more basic issue. Since white space is not one set spectrum across the country, these systems must have the ability to figure out which spectrum is empty and which is occupied in a given area at a given moment in time. It also must detect and avoid potential interference with broadcasters and wireless microphones, which also use this spectrum.

Thus, the industry had to develop agile radios that could play this detective game. One element of the solution was the appointment of database administrators. These companies, and the vendors supporting them, developed technology capable of tracking spectrum use in real time and communicating that information with each other.

This is not simple. It involves new science - as compared to tweaking existing technology. (At least one of these DBAs, Spectrum Bridge, runs a public website that makes it possible for anyone to check on spectrum by location.) Currently, there are nine DBAs with Microsoft waiting to hear whether it has been approved as well. "The nine database administrators have been working together since February of last year to iron out little issues and arrive at consistent assumptions and processes," said Neeraj Srivastava, vice president of business development for Spectrum Bridge.

Antennas and Auctions

For a technique that has gotten so much attention, a significant amount of issues still are outstanding about white space. "Basically, people have asked the FCC to change certain parts of the rules," said Mark Gibson, director of business development for Comsearch, one of the database administrators. "So the final disposition of what white space in the U.S. is hinges on what the FCC does on the petitions for reconsideration ... So this lack of clarity in the rules is causing the industry to hold up and wait until it gets cleared up."

The two biggest issues are antenna height and the impact of the potential auctioning of bandwidth. The higher the antenna, the longer the range of the white space transmitters. The problem is that the FCC rules, as they stand right now, proscribe fairly low antennas. There is a reason for this: White spaces, it turns out, aren't totally white. Very small amounts of signal - far less than what can be used to constitute a viewable picture - can travel long distances. The FCC is aware that many televisions are poorly constructed and could be impacted by the roaming signals, which drove it to limit the height of antennas. The fear was that conflicts would arise between white spectrum users and broadcasters.

Avoiding such conflicts makes sense. The problem, according to white space proponents, is that the current antenna heights are so low that it will make it impossible to use the technology in areas that are not essentially flat. All told, about half of the U.S. would not be able to use white space technology. There are petitions for reconsideration of antenna height before the FCC now, observers say.

Indeed, the rules are "good for the most part," said Paul Garnett, the director of interoperability and standards for Microsoft. "We think there will be a market there. There always are tradeoffs, and we are right now living with the FCC rules."

The other undecided issue is whether or not Congress will run incentive auctions of 120 MHz of spectrum. If that happens, those broadcasters will be moved to spots within the realm that vendors and operators hope to use for white space. "It raises questions of what would be available for white space and it would also impact the design and development of the databases," Gibson said.

It remains to be seen whether the FCC indeed will let the antennas grow or whether Congress - in these times of fiscal unpredictability - will try to raise revenue via another auction. Observers say that even if the white space industry gets answers they don't like from Congress and the FCC, businesses will be launched and bring value to subscribers, though it may be a bit more modest than if the FCC and Congress don't disappoint. Srivastava, for instance, said he initially expects proprietary gear to emerge. The IEEE, he said, are working on low-power (802.22) and high-power (802.11af) standards that could be used for white space.

Valuable Science

These experts add that the complex work of creating real-time databases is highly valuable beyond the parochial concerns of the white space industry. On one level, white space is not just important in the United States. A consortium in the UK started a white space trial in Cambridge, UK and the Scottish island of Bute earlier this month. Observers suggest that much of what is being done in that test is to catch up to developments during the past couple of years in the United States.

The biggest contribution of white space firms is that they add a valuable tool in the drive to stretch spectrum use. To date, wireless vendors and carriers generally have added to broadcasting capabilities simply by adding spectrum and developing more efficient equipment. The agile radios and interactive database technology - approaches that are viable far beyond the confines of white space - essentially open up an entirely new dimension. "We believe frequency sharing is the future of wireless," Srivastava said.

Now, for instance, a broadcaster may be able to use bandwidth at a particular spectrum spot during the day and a wireless Internet service provider (WISP) could use the same spectrum at night. Far more complex co-habitation arrangements are possible, especially as the technology is perfected. Put simply, the potential for stretching the spectrum soup is significant.

There is a tremendous amount that has not been finalized about the future of white space. The comforting news for the companies that have put money into research and development is that many of the key advances are universal and will provide significant benefits to users - and profit to them - going forward.

Add Comment      Leave a comment on this blog post

Jul 12, 2011 4:58 AM Chris Lyons Chris Lyons  says:

This is one of the most clear and complete summaries of the white space issue that I've seen anywhere.  Great job, Carl.  Very few writers correctly frame the "white space vs. auction/repacking" issue, most confuse white space with the 700 MHz band, and many completely ignore wireless microphones.  Well done!

Jul 12, 2011 5:38 AM Carl Weinschenk Carl Weinschenk  says: in response to Chris Lyons

Chris, that is very kind of you to take time to write such a nice note. I appreciate it very much. By the way, the three sources I had were very concise and articulate, which of course helps a lot.


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