Southern Company Services, Inc. 600 North 18 th Street Birmingham, AL 35203 December 13, 2019 VIA ECFS Marlene H. Dortch, Secretary Federal Communications Commission 445 12 th Street SW Washington, DC 20554 Re: Unlicensed Use of the 6 GHz Band, ET Docket No. 18-295; Expanding Flexible Use in Mid-Band Spectrum Between 3.7 and 24 GHz, GN Docket No. 17-183: Notice of Ex Parte Presentation Dear Ms. Dortch: On December 11, 2019, Coy Trosclair, Larry Butts, John Courtney, Andy Mills, Andy Collins, and Randall Watkins of Southern Company Services, Inc. (all by phone), Michael Rosenthal, Alan McIntyre and Kasey Chow of Southern Communications Services, Inc. d/b/a Southern Linc (“Southern Linc”), Allen Bell of Georgia Power Company, and George Stegall of Alabama Power Company (collectively, “Southern”), along with David Rines, outside counsel to Southern, met with Julius Knapp, Aspasia Paroutsas, Paul Murray, Michael Ha, Nicholas Oros, Barbara Pavon, Navid Golshahi, Hugh Van Tuyl, and Bahman Badipour (by phone) of the Office of Engineering and Technology (“OET”). During this meeting, we discussed the Commission’s proposals for allowing unlicensed operations in the 6 GHz band. 1 Southern explained that the 6 GHz band is uniquely suited for utility mission-critical communications over long paths where there is a lack of reasonable alternatives. Because of Southern’s extensive service area, and the need to communicate with facilities in very rural areas, the 6 GHz band is the only band that can accommodate Southern’s bandwidth and performance requirements and deploying fiber along these routes or relocating into an adjacent band is not economically feasible. In response to various proposals that have been presented in this docket, 2 Southern reviewed the feasibility and potential impact of relocating its 6 GHz paths into the 7 GHz band if that band were to be made available, and determined that the estimated cost of relocating its system would be over $20 million due to the equipment replacement and labor costs that 1 Unlicensed Use of the 6 GHz Band; Expanding Flexible Use in Mid-Band Spectrum Between 3.7 and 24 GHz , ET Docket No. 18-295, GN Docket No. 17-183, Notice of Proposed Rulemaking, 33 FCC Rcd 10496 (2018) (“ NPRM ”); See also Comments of Southern Company Services, Inc., ET Docket No. 18-295, GN Docket No. 17-183 (filed Feb. 15, 2019); Reply Comments of Southern Company Services, Inc., ET Docket No. 18-295, GN Docket No. 17-183 (filed March 18, 2019). 2 See, e.g. , Letter from Kara Graves, Director, Regulatory Affairs, CTIA, to Marlene H. Dortch, Secretary, Federal Communications Commission, ET Docket No. 18-295 (filed Nov. 8, 2019) at 2.
Page 2 December 13, 2019 would be involved. In addition to the financial costs, the implementation and timing of any such relocation would be very disruptive to Southern’s core utility operations. It is therefore Southern’s strong belief that utilities must remain in the 6 GHz band. Southern re-emphasized to the OET the vital importance of sufficiently protecting incumbent licensed operations in the 6 GHz band. In the case of utility communications systems, interference is life threatening, and the Commission must ensure that any rules it may adopt to allow unlicensed use of the 6 GHz band include sufficient protections to prevent “misconfigured” devices from causing interference to licensed 6 GHz operations. Southern again emphasized that, at a minimum, the Commission should require rigorous field-testing of any Automated Frequency Coordination (“AFC”) systems that may be proposed as a prerequisite to finalizing its rules for the 6 GHz band in order to ensure that the AFC system will work as planned. In addition, the Commission should require AFC for all unlicensed devices in the 6 GHz band, including indoor low power devices. Southern briefly addressed the various technical studies and reports that have been filed in the docket over the past few months. As an initial point, Southern clarifies that it is in full agreement with the reports that AT&T filed with and presented to the Commission, dated November 12 and November 21, 2019. 3 With respect to fade margin, Southern clarifies that it is in full agreement with the November 21, 2019 filing by the Fixed Wireless Communications Coalition (“FWCC”) explaining that there is no excess fade margin built into an FS link to soak up RLAN interference. 4 Southern’s paths are engineered to provide Industry Standard operation. Accordingly, a 30dB fade margin is required to maintain 99.999% propagation reliability, and even this results in a projected outage time of several hundred seconds per year. Any encroachment into that fade margin increases the outage time exponentially. To maintain our network reliability, fade margins must be protected. Southern was asked by the OET to provide information illustrating which of our paths we feel would be most susceptible to interference, and why, to aid in OET’s analysis. In response to OET’s request, Southern provides the information below. Southern has identified 129 paths/frequencies that it has in the 6 GHz range that carry critical traffic, including SCADA for grid reliability as well as network connectivity to generation plants and nuclear facilities. Of those paths, 17 are considered to be most susceptible to interference due to their location in or near metropolitan areas where RF saturation is most likely to occur. Although not in metropolitan areas, the other 112 paths/frequencies identified by Southern are nevertheless carrying critical traffic as described 3 See Letter from Michael P. Goggin, AT&T, to Marlene H. Dortch, Secretary, Federal Communications Commission, ET Docket No. 18-295 (filed Nov. 12, 2019); Letter from Stacey Black, AT&T, to Marlene H. Dortch, Secretary, Federal Communications Commission, ET Docket No. 18-295 (filed Nov. 21, 2019). 4 See Letter from Donald J. Evans, Counsel for the Fixed Wireless Communications Coalition, to Marlene H. Dortch, Secretary, Federal Communications Commission, ET Docket No. 18-295 (filed Nov. 21, 2019).
Page 3 December 13, 2019 above. It is therefore critical to Southern that these paths be free of any interference or RF saturation that will take away fade margin and ultimately the reliability of the path. Any interference can cause operational degradation and will require extensive expertise and troubleshooting time at the expense of Southern. It is the position of Southern that this situation must be avoided. Southern uses industry standard software tools to calculate a path link budget for its microwave paths. Free Space Path Loss ( i.e. , the loss between two isotropic radiators in free space, expressed as a power ratio), receiver sensitivity, transmitter power, antenna gain, coaxial cable and connector loss, and weather are all factors in calculating a link budget. Any path analysis in the licensed frequency range assumes zero interference coupled with sufficient physical and RF channel separation from adjacent frequencies as to not affect said path. Finally, Southern notes that the Commission and the Frequency Coordinators are an integral part of this process. When other entities enter the licensed frequency space, the path link budget will be less reliable. Southern’s calculations show 10dB of noise can cause 10dB reduction in fade margin (reliability) on a given path. Southern engineers a point-to-point microwave path with a minimum 30dB fade margin. Any encroachment into that fade margin increases the outage time exponentially. To maintain our network reliability, we must not allow our fade margins to be at risk. In accordance with Section 1.1206 of the Commission’s rules, this letter is being filed electronically in the above-referenced proceeding. Respectfully submitted, /s/ Coy Trosclair Coy Trosclair Director of Telecom Services Southern Company Services cc: Julius Knapp Aspasia Paroutsas Paul Murray Michael Ha Nicholas Oros Barbara Pavon Navid Golshahi Hugh Van Tuyl Bahman Badipour
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