Doug Lung /
FCC Proposes 3.5 GHz ‘Citizens’ Broadband Service
Plans to make available 100 MHz of shared spectrum
Wednesday the FCC announced
a proposal to make available 100 MHz of shared spectrum in the
3.5 GHz band using small cell and database technologies. The Notice
of Proposed Rulemaking (FCC 12-148) has the details. The NPRM
also seeks comment on including spectrum at 3650-3700 MHz, immediately adjacent
to C-band downlink spectrum. The FCC calls the new service in the 3550-3650 MHz
band the “Citizens Broadband Service” (CBS) and proposes three tiers of service
(1) Incumbent Access; (2) Priority Access; and (3) General Authorized Access
Incumbent Access (IA) would consist solely of authorized
federal and grandfathered licensed FSS (Fixed Satellite Service) 3.5 GHz band
users. These users would be protected from the other tiers by regulation and
technical means, including the use of exclusion zones where other CBS uses
would not be permitted.
Priority Access (PA) would be given to small cell use by
certain critical quality-of-service dependent users at specific target
locations, such as hospitals, utilities, state and local governments, “and/or
users with a distinct need for reliable, prioritized access to broadband
spectrum at specific, localized facilities.”
General Authorized Access (GAA) would allow opportunistic
use of the spectrum for a variety of residential, business and enterprise
purposes. They would have to protect Incumbent Access and Priority Access users
through technologies including geolocation and would not have an expectation of
protection from harmful interference. If the FCC includes the 3650-3700 MHz
band in the CBS, wireless Internet service providers using this band for links
would have to be licensed under GAA rules.
The NPRM proposes a “Spectrum Access System” (SAS) which
would govern interactions between devices in the 3.5 GHz band. It would be
modeled after the TV White Space database concept. Devices would be limited to
1 W. EIRP.
Users of C-band downlinks are likely to be concerned with
widespread use of 3650-3700 MHz, even for “small cell” systems. The FCC
addresses this in the NPRM, stating, “We are not aware of any known out-of-band emission issue in 3650-3700
MHz with neighboring bands. We note that the current deployment in 3650-3700
MHz band is subject to geographic protection requirements for federal and FSS
facilities and there is also a coordination requirement, which may be why there
is no interference issue. Understanding the current operating environment in
the 3.5 GHz Band, we seek comment on measures for limiting OOBE from Citizens
Broadband Service systems into the adjacent bands. We seek comment on the
appropriate OOBE limit for small cells in the 3.5 GHz Band.
The commission also asked about interference protection
threshold limits of relevant services in adjacent bands.
If the term “Citizens Broadband Service” has a 1970's ring
to it, this is no coincidence. The FCC is proposing to license users under
Section 95 of the FCC Rules, Personal Radio Services. That’s the same section
that includes Citizen's Band (CB) radio.