T-Mobile, Tech Companies Urge Limited FCC Role in Defining SAS Composition

The FCC should let network operators decide the best way to mitigate interference on the 3.5 GHz band, said a carrier, high-technology firms and other companies commenting on spectrum access systems for use on the 3550-3650 MHz band. SAS shouldn’t “directly control different aspects of the network,” T-Mobile said Monday (http://bit.ly/1ddo1fJ). Google and Microsoft also filed papers with the FCC on the technical aspects of the SAS in advance of a Jan. 14 workshop being hosted by the Wireless Bureau and the Office of Engineering and Technology. The FCC has targeted the band for shared commercial use.

T-Mobile urged allowing network operators to retain control of interference mitigation on the network because it “will help facilitate the development, adoption and maintenance of the 3.5 GHz band and avoid unnecessary complexity and the exchange of an excessive amount of information between the SAS and the operator’s network.” Direct SAS control of operators’ network operations on the band, however, will “greatly reduce the ability of operators to maximize use of the spectrum,” T-Mobile said. The FCC also needs to ensure careful planning of the interaction between the SAS and the 3.5 GHz band, because “the wrong architecture and functional requirements may severely limit the utility of the SAS by making it overly cumbersome,” T-Mobile said.

Nokia Solutions and Networks urged the FCC to define only the SAS’s general responsibilities and composition, leaving the definition of more detailed requirements up to “industry groups and standardization bodies that ideally include participation by the incumbent spectrum users, mobile operators, other potential new users, suppliers, and regulators.” The SAS “should only contain the relevant information on spectrum available for use by licensees” and “should not configure and/or set limits on various radio parameters to maximize efficient use of the band,” NSN said. The FCC should instead leave that configuration up to users on the band framework’s Priority Access tier, NSN said (http://bit.ly/1fblvZ7). Motorola Solutions said the SAS should “be responsible for generally de-conflicting use of the 3.5 GHz band,” especially providing spectrum access information to all tiers and assuring non-interference to the high-priority tiers. SAS should be aware of all active system deployments in the band to effectively manage the interference environment, and should inform all authorized users of spectrum opportunities on the band, Motorola Solutions said (http://bit.ly/1ejQk8F).

The FCC’s focus in creating rules for SAS operation should be “on the core functionalities necessary to allow multiple tiers of users to operate without unacceptable interference,” Google said. SAS should be able to authorize Priority Access and General Authorized Access (GAA) and provide interference protection for incumbent and Priority Access users, Google said. The company urged other basic requirements on competitive database operations, but said “further mandates could limit innovation and beneficial differentiation among SASs. So long as Priority Access users are protected from interference by GAA users and federal incumbents are protected from all commercial users in accordance with the Commission’s rules, database operators should be free to pursue independent methods of interference protection” (http://bit.ly/1cWJszX).

The 3.5 GHz plan needs to allocate “a sufficiently large amount of continuous spectrum to unlicensed, opportunistic” devices using the framework’s GAA tier -- at least 50 MHz, rather than the 40-50 percent of non-incumbent spectrum the FCC proposed, Microsoft said. Areas with high federal use of the band, including San Diego and Seattle, will have only a small amount of non-incumbent spectrum available, which won’t be sufficient for General Access users, “particularly if carriers reserve most of the Priority Access tier,” Microsoft said. The company said it has found that “50 MHz of contiguous usable spectrum is the minimum amount that is necessary to bring a new technology to commercial viability” (http://bit.ly/1koOKKf).

The Wireless Internet Service Providers Association said the SAS should be able to dynamically assign non-conflicting operating frequencies, detect instances of actual interference and automatically re-assign operating frequencies to resolve interference issues. To do this, SAS must be able to obtain geographic data on each network node -- including terrain and obstruction issues -- as well as information on each antenna, WISPA said. It also urged the FCC to require all participants on the band to use a common interface, which will ensure interoperability between all users and SAS systems (http://bit.ly/KB3Oou).