The looming conflict over spectrum sharing

Mike Dano

Any parent will tell you: It's not easy to get kids to share. The same, it seems, is true in wireless. There's a debate brewing over how to free up 100 MHz in the 3.5 GHz band for small cells, and the resolution could have significant implications on future spectrum regulations.

On one side of the debate are the FCC, Google (NASDAQ:GOOG), public-interest groups and others, which are pushing for a three-tiered spectrum-sharing arrangement that would provide spectrum for "General Authorized Access" users like individuals, small businesses and universities. On the other hand are T-Mobile US (NYSE:TMUS), Qualcomm (NASDAQ:QCOM), Nokia Siemens Networks and others, which are pushing for a two-tiered licensing system that could potentially dedicate more spectrum to wireless carriers' small cell deployments.

And the issue has gained importance following President Obama's recent memorandum that orders federal agencies to more efficiently use the spectrum they control and make it easier to share the airwaves with carriers. "Where technically and economically feasible, sharing can and should be used to enhance efficiency among all users and expedite commercial access to additional spectrum bands, subject to adequate interference protection for federal users, especially users with national security, law enforcement, and safety-of -life responsibilities," Obama wrote in the memo.

As the Public Interest Spectrum Coalition (a group of public-interest groups) noted in a recent FCC filing, the agency's ruling on 3.5 GHz spectrum sharing "is potentially a landmark in the commission's progress away from static 'command and control' licensing rules and toward more flexible and spectrum-efficient approaches that begin to harness the full potential of the nation's spectrum resources."

The FCC kick started the debate in December when it opened a proceeding on spectrum sharing in the 3.5 GHz band, with the stated goal of providing spectrum for wireless carriers' small cells. The proceeding represents an acknowledgement that small cells are likely to become increasingly important to wireless carriers' network deployment plans since they can support dramatic improvements to network capacity and coverage. According to Infonetics Research, the market for small cells will balloon to $2.7 billion by 2017.

In its notice on the proceeding, the FCC proposed a sharing arrangement that includes three tiers: 1, Incumbent Access, which would include authorized federal users and grandfathered fixed satellite service licensees; 2, Protected Access, which would include "critical use facilities, such as hospitals, utilities, government facilities, and public-safety entities;" and 3, General Authorized Access, which would include all other users, including the general public.

However, the FCC also agreed to consider comments for a two-tiered sharing structure that Qualcomm and others have been pushing since at least 2011. This proposal essentially removes the third "General Authorized Access" tier. Qualcomm's proposal, dubbed Authorized Shared Access (ASA), is similar to the Licensed Shared Access (LSA) that is being considered among European carriers. The European Telecommunications Standards Institute (ETSI) is working to standardize ASA/LSA technology.

And it appears that the FCC is taking a serious look at Qualcomm's proposal: "Qualcomm has done a great deal of work and put a lot of thought into solving this problem, and I want to commend them for it. They offer an interesting viewpoint, and we are carefully considering their proposal," said Ruth Milkman, chief of the FCC's Wireless Telecommunications Bureau, during a speech earlier this month at the Georgetown Center for Business and Public Policy and PCCA Workshop. "But, as we do with all stakeholder proposals, we will keep in mind it is one viewpoint among several competing visions for this band. Staff is working, again across multiple disciplines, and in close coordination with our federal counterparts, to develop recommendations for the commission."

In filings with the FCC, Qualcomm argues that its ASA model, which relies on a Spectrum Access System (SAS) database, would support sharing based on geography, location, time or frequency band. Qualcomm said its ASA technology would provide spectrum only to "a discrete, identifiable group of operators" and would allow "a licensed network operator to tightly manage access to the ASA spectrum … in order to provide all users with a reliable quality of service, with all the proven interference management/mitigation/cancellation techniques available in today's licensed mobile broadband technology."

Others, including, T-Mobile, have voiced support for Qualcomm's approach. "The sharing approach that the commission proposes is unnecessarily complex," T-Mobile wrote in an FCC filing, arguing that the ASA/LSA approach from Qualcomm and others is becoming standardized in Europe, provides a more reliable quality of service for licensees and better protects federal users.

(T-Mobile's support for the two-tiered spectrum-sharing concept is notable considering T-Mobile last year obtained FCC permission to test spectrum sharing in the 1755-1780 MHz band. A T-Mobile spokesman declined to provide an update on T-Mobile's spectrum-sharing tests, but in a recent FCC filing the carrier said "progress has been made on creating a roadmap for clearing and sharing with federal systems in the 1755-1780 MHz band.")

On the other side of the conflict sits, among others, PISC and Google, which urged the FCC to retain the GAA sharing tier in its final rules for the 3.5 GHz band. "The proposed geolocation-enabled dynamic database will permit GAA devices to access available spectrum at a particular location, without interfering with existing incumbent (or secondary exclusive) uses," Google wrote in an FCC filing.

"All evidence today suggests that the greatest value of another small cell band for consumers, ISPs of all kinds (mobile, cable, WISPs) and for adjacent markets (chips, devices, apps and services) will be the widespread adoption at the edge of GAA use," added the PISC. "Both mobile device data offload and machine-to-machine innovations are far more likely to proliferate in this band at massive scale than would be the case if the band is carved up into exclusive licensing zones or access subscriptions with high transaction costs."

To be clear, the 3.5 GHz band is not the first place the FCC has dabbled in spectrum sharing. As industry analyst and FierceWireless contributor Peter Rysavy pointed out in a 2012 report on the topic, AWS licensees are required to protect from interference 16 Department of Defense facilities located throughout the nation in the 1710-1755 MHz bands. And the FCC continues to test spectrum sharing in TV white spaces through databases supplied by Google, Key Bridge Global and others.

Whatever the FCC ultimately decides in the 3.5 GHz band will likely set the tone for other spectrum-sharing agreements. And there will likely be a wide range of spectrum-sharing arrangements in the coming years as the wireless industry works to get access to the enormous swaths of spectrum currently in the hands of federal users. --Mike | +Mike Dano | @mikeddano