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Opening Up of 3.65 GHz Band Has Begun


Challenges and Demands of New Guidelines


A new global trend for the 3.65 GHz band is emerging due to the recent U.S. Federal Communications Commission’s Report and Order opening up 150 MHz for shared access in the 3550-3700 MHz band to wireless broadband service providers, industrial users, and other federal/non-federal users. This is a significant operational change for the 3.65 GHz wireless broadband community, critical infrastructure players, and specifically global WiMAX deployments, which demand solid guidelines, policies, and industry support to have adequate protection.

The WiMAX Forum Smart Energy Working Group (SEWG) has been closely monitoring this activity and is working closely with ecosystem players to develop such guidelines so 3.65 GHz users can continue to leverage this band. SEWG’s daily interactions with the FCC, WinnForum, and other rule makers have perfectly positioned SEWG at the heart of the 3.65 GHz band policy-making debate and Spectrum Access System (SAS) development.

The WiMAX Forum will host a free live webinar on Wednesday, June 3 at 10AM PDT, which is open to all companies seeking more details and wanting to influence the outcome. To pre-register for the webinar, please visit click here to register.

Only member companies have access to the related documents posted by SEWG in the member’s portal and are entitled to benefit from the Forum’s centric role in shaping the 3.65 GHz band’s future. Join the WiMAX Forum today! If you have questions, please contact

WiMAX Forum® – May 12, 2015

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Introduction - On April 21, 2015, the U.S. Federal Communications Commission (“FCC”) released a Report and Order (“Report and Order”) creating a new Citizens Broadband Radio Service (“CBRS”) that will permit commercial use of 150 MHz of spectrum in the 3550-3700 MHz band (“3.5 GHz Band”). It contains the band 3650-3700 MHz which includes the 3.65 GHz Wireless Broadband Service (“WBS”).

As summarized below, the Report and Order adopts rules for making the band available in phases for wireless broadband and other innovative uses through a three-tiered sharing framework enabled by a Spectrum Access System (“SAS”) that will establish frequency and power usage restrictions to protect incumbent users from interference.

Three-Tiered Framework - The federal/non-federal users’ sharing arrangement is part of a broader three-tiered sharing framework enabled by an SAS. Incumbent users (the “Incumbent Access” tier) represent the highest tier in this framework and receive interference protection from CBRS users. Protected incumbents include the authorized federal users, as well as Fixed Satellite Service (“FSS”) and, for a finite period, grandfathered terrestrial wireless operations in the 3650-3700 MHz portion of the band. The CBRS itself consists of two tiers—Priority Access and General Authorized Access (“GAA”)—both authorized in any given location and frequency by an SAS. As the name suggests, Priority Access operations receive protection from GAA operations. Priority Access Licenses (“PALs”), defined as an authorization to use a 10 MHz channel in a single census tract for three years, will be assigned in up to 70 MHz of the 3550-3650 MHz portion of the band. GAA use will be allowed, by rule, throughout the 150 MHz band. GAA users will receive no interference protection from other CBRS users. The SAS serves as an advanced, highly automated frequency coordinator across the band. It protects higher tier users from those beneath and optimizes frequency use to allow maximum capacity and coexistence for both GAA and Priority Access users.

General Authorized Access - A maximum of 70 MHz, i.e., seven channels, may be reserved for PALs in any given license area at any time; the remainder of the available frequencies will be made available for GAA use. Where the band is not utilized by Incumbent Access users or Grandfathered Wireless Broadband Licensees, GAA users will have access to a minimum of 80 MHz. The presence of Incumbent Access users could affect the amount of spectrum available for both GAA and PAL users. Nevertheless, the policies adopted in the Report and Order, including the ability to access unused PAL channels, will ensure that substantial spectrum capacity is available in all geographic areas for GAA use.

Priority Access License - The Report and Order emphasizes that PAL licensees will always have the right to use the full 10 megahertz channel bandwidth within their license areas during their license terms. PAL channels may not be subdivided by an SAS without the licensee’s consent. The Report and Order observes that there is nothing in the rules to prevent a PAL licensee from using the remainder of the band on a GAA basis under the same conditions that apply to all GAA users. Indeed, it expects that most, if not all, PAL licensees will also be GAA users. The FCC decided not to issue PALs in the 3650-3700 MHz band, but PAL licensees can be expected to operate in that band on a GAA basis.

The Grandfather Period - The FCC decided to establish a limited grandfather period for certain WBS fixed and base stations. This grandfather period extends until April 17, 2020 (five years after adoption of the 3.5 GHz Order), or, for incumbents licensed as of January 8, 2013, the remainder of an incumbent’s license term, if that is longer than April 17, 2020. During the grandfather period, the grandfathered WBS fixed and base station sites will be in the Incumbent Access tier, and thus eligible for protection from interference from GAA users (as noted above, PALs will not be issued in 3650-3700 MHz). However, this grandfathered protection will only be available in “Grandfathered Wireless Protection Zones”. 

The FCC will determine a Grandfathered Wireless Protection Zone, after issuing a public notice seeking comment on technical issues, around only those base and fixed stations that are (1) registered by applications filed in ULS on or before April 17, 2015 and (2) constructed, in service, and in full compliance with the rules by April 17, 2016. Additionally, the Grandfathered Wireless Protection Zone will be reduced should any portions of the protected network fail to meet the above criteria after April 17, 2016. Any registrations filed after April 17, 2015 will only be afforded protection from harmful interference within the licensee’s Grandfathered Wireless Protection Zone. Incumbent operators will be required to register their frequency usage with SAS administrators to be afforded Grandfathered Wireless Broadband Provider protections.

During the transition period, Grandfathered Wireless Broadband Licensees may also register sites outside their Grandfathered Wireless Protection Zones, but such sites will not be entitled to CBRS interference protection. The FCC expects all Grandfathered Wireless Broadband Licensees to comply with the CBRS rules once their transitions are complete.

After the Grandfather Period - At the end of the grandfather period, licensing under the WBS will no longer be available. Thus, the incumbent WBS providers will have the option to continue operating their networks under the CBRS rules for GAA operations or to move to a different spectrum location.

To preserve existing 3650-3700 MHz investment, the technical rules for Category B CBSDs (representing high-power uses as opposed to Category A) will accommodate existing 3650-3700 MHz deployments in urban areas and will increase flexibility in rural areas. In addition, equipment deployed under existing rules will be exempted from the operability requirement. Finally, the FCC has defined a CBSD as a network of base stations, allowing legacy networks to interact with the SAS as required after the transition through a proxy controller device.

Second Further Notice of Proposed Rulemaking - The 3.5 GHz Order also included a further notice of proposed rulemaking (“FNPRM”) that, among other things, seeks comment on five issues relating to the in-band protection of FSS in the 3650-3700 MHz band.

Although PALs are not going to be an option in the 3650-3700 MHz band, they will be available in the 3550-3650 MHz portion of the band and as such, represent viable long-term licensing alternatives for incumbents in the 3650-3700 MHz band for growing their network and for new licensees. The 2nd FNPRM seeks comments on several issues regarding PALs that warrant consideration. The Commission seeks comments on how PAL usage is defined, be it engineering-based or economically-based. Comments are also requested on PAL payment options: should they be similar to existing rules or modified. The 2nd FNPRM also seeks comments that address the question of a secondary market for PALs and, in that context, the concept of a spectrum exchange to ensure liquidity in a secondary market.

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