The US FCC is making plans to open up its 3.5GHz spectrum, through small cells and spectrum sharing, to create a Citizens Broadband service. Guy Daniels reports.
The US regulator has started to open up the 3.5GHz band for small cell usage, in the hope of creating a ‘Citizens Broadband Service’. The FCC wants new service entrants to share this spectrum with incumbent operators. The spectrum is currently in use by the US Navy for its radar operations and covers around 60 per cent of the country’s population.
The FCC has adopted a Notice of Proposed Rulemaking (NPRM) regarding commercial operations in this spectrum, covering both small cells and spectrum sharing.
Note though that this 3,550-3,650MHz band is not part of the 300MHz that the FCC had previously identified for allocation for mobile “flexible use” before 2015. However, the FCC is seeking comments on whether to include the neighbouring 3,650-3,700MHz band under its new proposed rules.
The FCC describes small cells as:
“Low-powered wireless base stations intended to cover targeted indoor or localized outdoor areas ranging in size from homes and offices to stadiums, shopping malls, hospitals, and metropolitan outdoor spaces.”
It adds that they can take advantage of greater reuse of “scarce” wireless frequencies. For example, it says deploying ten small cells in a location in place of a single macro cell could result in a tenfold increase in capacity, using the same quantity of spectrum.
As for spectrum sharing, the FCC says in this context it refers to:
“The use of automated techniques to facilitate the coexistence of disparate unaffiliated spectrum dependent systems that would conventionally require separate bands to avoid interference.
Such coexistence may happen, for example, by authorizing targeted use of new commercial systems in specific geographical areas where interference into incumbent systems is not a problem.”
As an example, the FCC says that the military may need spectrum for radar systems or hospitals may deploy networks to enable real-time monitoring of patient vital signs, however, many of these uses are highly localized in nature. Therefore, according to the FCC:
“More agile technologies and sharing mechanisms could potentially allow large quantities of special-purpose federal and non-federal spectrum to be used for more general purposes, such as commercial broadband services, on a shared basis.”
The FCC proposes to structure its new Citizens Broadband Service according to a multi-tiered shared access model – incumbent access (i.e. federal government); priority access (such as hospitals and public safety); and general authorised access (in other words, the general public, mobile operators and ISPs). It would be managed by a spectrum access system with a dynamic database and other interference mitigation techniques, modelled on the existing geolocation-enabled TV white spaces database.
According to FCC Chairman Julius Genachowski, the US has a chance to lead the world in putting the 3.5GHz spectrum to use.
“This is spectrum that generally is available around the world, but with this proceeding, we are becoming the first country of scale to be moving forcefully to put this spectrum to work in the marketplace.”
The FCC also believes that this fresh approach could serve as a model for shared access to spectrum in several other bands currently being used by federal operators, improving efficiency across the spectrum ecosystem and helping to address the growing demand for spectrum for broadband uses.
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