U.S. Cellular files for STA to conduct 3.5 GHz tests

Skowhegan, Maine, is one of the areas where U.S. Cellular proposes to conduct 3.5 GHz tests. (Image: Skowhegan Area Chamber of Commerce)

U.S. Cellular submitted an application last week for a six-month special temporary authority (STA) to conduct experimental testing in the 3.5 GHz band in parts of Maine and North Carolina.

The testing will involve studying the radio propagation characteristics of frequencies in the proposed Citizens Broadband Radio Service (CBRS) spectrum to help determine the applicability of the spectrum to support various future wireless services, according to the application. U.S. Cellular wants to start the STA clock on June 26 and run through Dec. 26, 2017.

Specifically, the locations would be in suburban and rural areas in Penobscot and Somerset counties in Maine and in Buncombe and Henderson counties in North Carolina. Cities include Hendersonville and Candler in North Carolina and Charleston and Skowhegan in Maine.

Plans call for testing multiple base units and multiple mobile units, but vendors of the gear are not identified. U.S. Cellular says the base station equipment will be mounted on existing U.S. Cellular tower facilities and will transmit at a maximum EIRP of 47 dBm/10 MHz, consistent with the proposed CBRS rules for Class B CBRS Base Station Devices. The user equipment will transmit at a maximum EIRP of 23 dBm, also consistent with proposed CBRS rules. LTE modulation will be used with up to two 20-MHz carriers within the 3550-3600 MHz spectrum.

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U.S. Cellular’s desire to conduct 3.5 GHz tests comes after other carriers also have said they plan to deploy 3.5 GHz gear when it becomes practical to do so. The 3.5 GHz spectrum band is used in other countries, but the way it’s set up in the U.S. for commercial purposes involves a unique three-pronged sharing system directed at incumbents, priority access license (PAL) and general authorized access (GAA) users.

The FCC and CBRS community are still working to establish the system where spectrum access and operations will be managed by a dynamic spectrum access system, conceptually similar to the databases used to manage Television White Spaces devices. 

U.S. Cellular, along with AT&T, Verizon, T-Mobile USA and Sprint, is a member of the CBRS Alliance. Last week, the Wireless Innovation Forum (WInnForum) and CBRS Alliance announced the signing of an agreement of cooperation on commercializing the 3.5 GHz CBRS band. The groups plan to extend mutual invitations to provide contributions and comments, possibly hold joint workshops and meetings, share their roadmaps and planning schedules and nominate observers to sit on committees that are applicable to their shared interests.

WInnForum has been working on standards for CBRS while the CBRS Alliance primarily has focused on advocacy. The charters of the two organizations are complementary enough that they wanted a more formal pairing, with WInnForum addressing overall CBRS aspects and the CBRS Alliance promoting LTE-based solutions in the CBRS band. Many of the same members are in both groups.