Friday saw a couple of FCC actions on 3.5 GHz. It was announced that the Citizens Broadband Radio Service (CBRS) will tentatively be on the agenda for the FCC’s April 17 meeting.
The Commission will consider a Report and Order and Further Notice of Proposed Rulemaking that would leverage innovative spectrum sharing technologies to make 150 megahertz of contiguous spectrum available in the 3550-3700 MHz band for wireless broadband and other uses.
In addition, Chairman Wheeler blogged on some CBRS elements in the draft Report and Order.
The draft Report and Order implements a three-tiered sharing paradigm, which we have explored in multiple rounds of notice and comment over the past two years. The lowest tier in the hierarchy, General Authorized Access (GAA), is open to anyone with an FCC-certified device. Much like unlicensed bands, GAA will provide for zero-cost access to the spectrum by commercial broadband users. In the Priority Access tier, users of the band can acquire at auction targeted, short-duration licenses that provide interference protection from GAA users. Finally, at the top of the hierarchy, incumbent federal and commercial radar, satellite, and other users will receive protection from all Citizens Broadband Service users.
This new tiered sharing paradigm will be enabled by a Spectrum Access System. The SAS takes an age-old role in spectrum management – the frequency coordinator – and updates it for the 21st century through the use of cloud computing technology. Long gone are the days of an engineer working with pencil and protractor (not to mention pocket protector) to coordinate users into a band.
Finally – a few words on protecting incumbent federal uses. America’s military uses this band for radar systems that perform vital national security missions. To protect these radars, previous reports suggested very large zones around the coasts within which commercial users could not operate. Thanks to an enormous amount of collaborative work with NTIA and the Department of Defense, these zones are now substantially smaller. More importantly, the draft Report and Order provides a roadmap, recommended by NTIA and DoD, for operations within any area around the coast through the use of new sensor technologies.
That last paragraph is consistent with the NTIA filing I wrote about on Thursday. The NTIA document has some more detail that I expect reflects consensus between it and FCC staff. So, I see it as supplementing the Chairman’s comments.
On SAS, NTIA recommends that it have the following capabilities:
- Authorize CBSDs to operate at a given location given certain parameters such as the operating frequency and maximum transmit power level
- Ensure that [Priority Access] and GAA users do not operate in the exclusion zones established to protect federal radar systems
- Synchronize with other SASs to ensure protection of federal systems
- Operate without any connectivity to any military or other sensitive federal databases or systems
- Ensure operational information (e.g., on the movements or positions of federal systems) is not stored, retained, transmitted, or disclosed
- Provide for manual override by area or time that has the capability to trigger changes in commercial use necessary to comply with general FCC enforcement actions or to respond to emergency instructions from the President of the United States, or another designated federal government entity, issued pursuant to Section 606 of the Communications Act, as amended
On sensing, NTIA recommends an optional element called Environmental Sensing Capability (ESC), a system of sensors that informs an SAS about the presence of federal operations to be protected. The SAS would then direct users to move to another channel or stop transmitting. NTIA recommends the following objectives for the ESC:
- Commercially-owned and operated. The ESC should be commercially owned and operated by SAS administrators or a third-party servicing one or more SAS administrators. The Federal Government should not be expected to operate an ESC.
- Technological flexibility. Sensing of incumbent radar signals could be accomplished through a dedicated sensing infrastructure, device-based sensing, or a combination of the two.
- Non-retention and disclosure of military operations. The ESC shall not store or disclose platform movement or position information with respect to sensitive data related to military operations, nor should it be implemented in a manner that could provide insights into operations of federal systems or otherwise affect the Department of Defense’s (DoD) operational security posture.
- Geographic relevance. The ESC will not be necessary everywhere, but only in the vicinity of the exclusion zones established to protect the federal radar systems (i.e., along the coasts for shipborne radars and near facilities used for ground-based radar operations).
I expect this agenda item will be approved on April 17. If there’s little or no dissent, we might see the text soon thereafter.