AT&T, Google and others pick apart FCC's 3.5 GHz spectrum-sharing scheme

The FCC has a lot of work ahead if it hopes to create consensus around its plans for a Citizens Broadband Radio Service (CBRS) at 3.5 GHz, as specific parts of its proposed rulemaking have come under attack from multiple corners.

Wireless industry players that sent in comments by the July 14 filing deadline were largely supportive of efforts to engage spectrum-sharing techniques to open the band for use by both government and commercial users. The spectrum-sharing concept provided a rare point of general agreement, however, with many details of the FCC's proposal drawing considerable debate.

The commission intends to apply spectrum sharing to 3550-3650 MHz spectrum and is also pondering extending the service to 3700 MHz, providing a total of 150 MHz of spectrum for the CBRS. The FCC's three-tiered access and sharing model would be comprised of federal and non-federal incumbents, priority access licensees (PALs) and general authorized access (GAA) users, which would basically be an unlicensed tier.

It is envisioned that opening up the band in this manner would encourage its use for wireless broadband, small cell deployments and other applications.

Google's (NASDAQ: GOOG) comments on the FCC proposal echoed numerous others in saying the commission should revise its "improperly conceived" exclusion zones protecting incumbent government users, which would deny access to more than half of the U.S. population.

In addition, the Internet giant added that basing priority licenses on census tracts "will waste spectrum resources." Google noted that carriers "often will be unable to deploy a small cell network within a single census tract."

Yet while Google supports the commission's plan to have a centralized spectrum manager, or Spectrum Access System (SAS), assign channels dynamically, others see lots problems with the SAS.

AT&T (NYSE: T), for example, said the "novel" SAS may prove a good approach for managing the 3.5 GHz band, but said it strongly opposes the FCC's proposal to have the SAS make dynamic--as opposed to static--spectrum assignments for PALs. "In the case of PALs, real-time or near real-time interference management is not practical between PAL users due to stringent interference reporting requirements that will be difficult to be met by the proposed SAS architecture and also due to the disparity of technologies that can be used by PAL users," AT&T said.

The operator recommended the commission consider a transitional approach to licensing during SAS development, during which spectrum use would be bifurcated between PAL and GAA users.

T-Mobile US (NYSE:TMUS) said the SAS should have significant authority over spectrum management but only in the GAA segment of the band.

The operator also called on the FCC to reevaluate its allocation of spectrum between PALs and GAA users and set a floor of 40 MHz of spectrum for priority-access use; reconsider the protection zones; issue licenses to PALs using more traditional licensing mechanisms, such as using areas larger than census tracts, at fixed frequencies, and for terms greater than one year; set flexible technical rules, allowing higher power levels for licensed services; and limit the role of the SAS, particularly as it relates to licensed spectrum.    

The controversial three-tier licensing framework for the CBRS has numerous supporters, including Google. However, Qualcomm (NASDAQ:QCOM) continues to take issue with the approach, which, it said, "has not been implemented anywhere in the world."

The chipmaker noted multiple vendors, European operators and some regulators outside of the United States have been working to standardize within ETSI a two-tier spectrum-sharing framework commonly referred to as authorized shared access (ASA) or licensed shared access (LSA). That approach has been selected for deployment in the European Union's 2.3 GHz band.

Qualcomm (NASDAQ:QCOM) said the FCC's three-tier plan, with its "ultra-small geographic areas with ultra-short licenses" will delay small cell deployment in the 3.5 GHz band.

Sprint (NYSE: S), meanwhile, sided with entities such as the WiMAX Forum in opposing the FCC's proposal to include the 3650-3700 MHz band in the CBRS at this time.

"Sprint currently holds a license in the 3650-3700 MHz band, and has worked with several vendors to test and develop equipment that would operate under the existing Part 90 Subpart Z rules, including small cells and non-line-of-sight backhaul," the operator said. It added that the FCC's proposal to include the 3650-3700 MHz band under the new Part 96 rules "has brought uncertainty to that work."

For more:
- see this Google filing
- see this AT&T filing
- see this T-Mobile filing
- see this Verizon filing
- see this Sprint filing   

Related articles
Verizon, Qualcomm and Ericsson partner on field trials of 3.5 GHz spectrum sharing
3.5 GHz: Debate continues on spectrum sharing, band plan and unlicensed use
3.5 GHz spectrum-sharing database 'could get very complicated,' says Accenture exec
AT&T, WiMAX Forum cite separate problems with FCC's 3.5 GHz plan
AT&T wants 3.5 GHz band divided into sub-bands to promote small cell deployment
FCC's latest proposal for 3.5 GHz band includes auctioned licenses
The looming conflict over spectrum sharing

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