In 2008, in the wake of the 700 MHz auction, Google held a conference call to reveal its plans for “Wi-Fi on steroids” – a broadband wireless service to be delivered coast to coast via unlicensed white space devices, all in time for the 2009 Christmas holiday. I remember reading a blog comment around that time mocking AT&T and Verizon for “wasting” billions of dollars on licensed spectrum in the 700 MHz auction when troves of valuable unlicensed spectrum would soon be available for free.
In 2010, the FCC adopted white space rules that white space supporters argued set the stage for the next generation of wireless technologies to emerge. One reporter declared that “there is no stopping the white space gold rush that is about to begin.”
It’s now 2015. The licensed 700 MHz allocations that were sold in 2008 have been the bedrock for billions of dollars of investment in wireless networks that now form the catalyst for U.S. leadership in LTE wireless technologies. And hundreds of millions of U.S. consumers now enjoy 4G LTE wireless services as a result of those investments.
On the white spaces front, an Internet search reveals only a scattering of small scale white spaces tests and deployments, with even less information available about the scope or success of those efforts.
Perhaps the most insightful evidence of white space activity comes from an emergency petition on the White Space Database recently filed by the National Association of Broadcasters (NAB). From this petition we learn two critical facts. First, after five years of effort, there are fewer than 1,000 devices registered in the database. Apparently the gold rush was not even a trickle.
Second, the database – which is supposed to be the primary means of assuring that interference can be effectively managed – is riddled with inaccuracies and errors.
These issues are important. Policymakers increasingly view spectrum sharing as policed by a database-driven frequency manager as critical to the future of U.S. spectrum policy. In both the 3.5 GHz proceeding as well as in connection with the incentive auction, the FCC envisions permitting significant unlicensed allocations directly adjacent to a variety of licensed uses. The assumptions underlying this approach are that a database can accurately manage the scope of unlicensed use while providing accurate information on the users so interference concerns can be addressed. NAB’s petition now exposes those assumptions to some serious doubts.
Even in the best circumstances, real time external monitoring and management of a complex interference environment is a tall order. But we now learn that database providers have not been able to effectively maintain information on less than 600 TV white space devices. This raises serious questions about the ability of a database to patrol the complexities involved in robust spectrum sharing, including in the 3.5 GHz band.
On the 600 MHz front, the wireless industry has already filed a study raising significant questions about the protection thresholds proposed by the FCC for unlicensed use in the 600 MHz guard bands. On top of those concerns we must now add questions about whether unlicensed users will provide reliable location, device and contact information that will be essential to resolving interference concerns should they arise.
AT&T continues to support unlicensed uses in appropriate use case scenarios. AT&T’s over 30,000 Wi-Fi hotspots bring mobile broadband connections to Wi-Fi enabled devices virtually everywhere our customers go. But unlicensed services should not be permitted at thresholds that create interference into neighboring licensed allocations, particularly in the 600 MHz band. And if the industry will be dependent on database policing to manage complex interference environments, the FCC must ensure that unlicensed users comply with database requirements. For these reasons, NAB’s petition raises important issues that deserve attention.