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FCC Seeks Comments on 3.6 GHz ‘Citizens Broadband Service’

The FCC has taken the next step in the creation of a new “Citizens Broadband Service” in the 3550-3650 MHz frequency band. This proposal for the new service was covered in a Notice of Proposed Rulemaking (NPRM) released last December and this past Friday the FCC issued a Public Notice seeking comment on licensing models and technical requirements in the 3550-3650 MHz band.

While there is concern about the impact this service would have on incumbent federal and Fixed Satellite System (FSS) users, the FCC said the request for comments was for its revised framework, and would not cover potential out-of-band interference issues. It said it may release additional public notices to supplement the record on these or other issues. A workshop on the technical issues of the Spectrum Access System (SAS) is also planned.

The Revised Framework that the FCC is proposing includes these items:

•An SAS to dynamically manage frequency assignments and automatically enforce access to the Priority Access and GAA tiers

•Open eligibility for Priority Access tier use

•Granular but administratively-streamlined licensing of the Priority Access tier

•Mutually exclusive spectrum rights for Priority Access subject to licensing by auction, coupled with a defined “floor” of GAA spectrum availability, to ensure that GAA access is available nationwide (subject to Incumbent Access tier use)

•Additional GAA access to unused Priority Access bandwidth, as identified and managed by the SAS, to maximize dynamic use of the unutilized portion of the band and ensure productive use of the spectrum

•Opportunities for critical infrastructure facilities to obtain targeted priority spectrum use within specific facilities (such as a building) that meet certain requirements to mitigate the potential for interference to and from other band users; and a set of baseline technical standards to prevent harmful interference and ensure productive use of the spectrum

The FCC identified 10 MHz unpaired channels as a standard PAL (Priority Access License) bandwidth. It seeks comment on how much bandwidth should be allowed for general access (GAA). The SAS model would dynamically assign specific frequencies in a geographic area. The approach would be similar to that adopted for TV band white space devices. Small cell base stations would be limited to a maximum of 24 dBm along with a maximum antenna gain of 6 dBm, allowing a maximum ERP up 30 dBm. User devices would have a configurable maximum power level below a typical 23 dBm values and support for some form of power control.

This is a short summary of what the FCC is proposing and requesting comment on. For additional information, refer to Public Notice FCC 13-144 and my previous article FCC Proposes 3.5 GHz ‘Citizens’ Broadband Service.

Doug Lung is one of America's foremost authorities on broadcast RF technology. He has been with NBC since 1985 and is currently vice president of broadcast technology for NBC/Telemundo stations.