LeoSat Ex Parte (9-1

LETTER submitted by LeoSat MA, Inc.

LeoSat Letter

2017-09-19

This document pretains to SAT-PDR-20161115-00112 for Petition for Declaratory Ruling on a Satellite Space Stations filing.

IBFS_SATPDR2016111500112_1278637

1 8 0 0 M S T R E E T, N W SUITE 800N WASHINGTON, DC 20036 TEL 202.783.4141 FA X 202.783.5851 W W W.W B K L AW. C O M September 19, 2017 VIA ECFS & IBFS Ms. Marlene H. Dortch Secretary Federal Communications Commission 445 12th Street, S.W. Washington, D.C. 20554 Re: Update to Parts 2 and 25 Concerning Non-Geostationary, Fixed-Satellite Service Systems and Related Matters, IB Docket No. 16-408 Petition for Declaratory Ruling of LeoSat MA, Inc., IBFS File No. SAT- PDR-20161115-00112 Dear Ms. Dortch: LeoSat MA, Inc. (“LeoSat”) hereby responds to the ex parte letter filed by WorldVu Satellites Limited (“OneWeb”) on September 10, 2017, in the above referenced proceedings. Among other things, OneWeb’s letter addresses LeoSat’s pending petition for declaratory ruling (“PDR”) seeking access to the United States market to provide broadband fixed-satellite services (“FSS”) using a Ka-band low-Earth orbit (“LEO”) non-geostationary satellite orbit (“NGSO”) system. 1 Specifically, LeoSat makes this filing to correct two inaccurate assertions made by OneWeb regarding LeoSat’s PDR’s EPFD technical demonstration: (i) that the PFD masks show “erratic behavior”; and (ii) that the Earth Station density calculations were incorrect. PFD mask In its ex parte submission, OneWeb may have misinterpreted the PFD masks provided by LeoSat by showing a 2D view (i.e., PFD vs alpha angle), while, in fact, for a given satellite latitude, the PFD mask should be represented in three dimensions: PFD vs alpha angle and delta_longitude. As a result, OneWeb wrongly asserts that the PFD masks provided by LeoSat show “erratic behavior” without “physical analogy,” potentially leading to the underestimation of the EPFD results. 1 See Notice of Ex Parte Letter from WorldVu Satellites Limited, LeoSat MA, Inc., IBFS File No. SAT- PDR-20161115-00112 (Call Sign S2979) (Sept. 10, 2017).

September 19, 2017 Page 2 Specifically, the delta_longitude parameter represents the difference in longitude between the LeoSat sub-satellite point and the GSO longitude. Because LeoSat’s proposed NGSO system uses fixed EIRP beams, the PFD decreases when the delta_longitude increases and the slant path becomes longer and the spreading higher. The two figures below show the same mask for a LeoSat satellite at 20° latitude from two different viewpoints. These are the same datasets evaluated by OneWeb, but they are properly depicted below in three dimensions rather than the two dimensions used by OneWeb in its ex parte letter. Each dot on the figures represents a PDF value in the mask for a given alpha angle and delta_longitude angle. -130 -140 -150 pfd -160 -170 -180 100 50 40 0 20 0 -50 -20 -40 -60 -100 -80 delta longitude alpha -120 -140 pfd -160 -180 100 80 60 40 20 40 0 20 -20 0 -40 -20 -60 -40 delta long -80 -60 alpha -100 -80

September 19, 2017 Page 3 When properly graphed in three dimensions, the surface on the top of the mask is smoothly curved and continuous with a steep PFD decrease within the GSO avoidance area (alpha angle between -7° and +7°), and it does not depict any “erratic” behavior. By contrast, OneWeb mistakenly represented the data from a “side view” (PFD vs alpha angle), where all points for the different values of delta_longitude are represented on the same plane. OneWeb also erred when it plotted a line joining all those points as seen in the two figures below. Appropriate dot representation: -130 -135 -140 -145 -150 -155 pfd -160 -165 -170 -175 -180 -80 -60 -40 -20 0 20 40 alpha Inappropriate line plot representation using the same dataset: The latter line plot representation is inappropriate because points belonging to different delta_longitude slices are joined by a fictitious continuous line. For the foregoing reasons, OneWeb’s assertions about LeoSat’s PFD mask discussed above are simply mistaken. The PFD mask used by LeoSat in its PFD analysis is appropriate and accurate. Earth Station Density OneWeb asserts that the average distance between co-frequency cells must be related to the average density of earth stations per km² by the relation: density = 1/(average_dist)². The mere fact that the International Telecommunications Union EPFD software requires and

September 19, 2017 Page 4 processes these two parameters independently, however, indicates that they are not necessarily equivalent. 2 LeoSat has provided in its PFD mask the values for these parameters that best reflect its foreseen deployment plans, and this approach is reasonable. However, even if the mathematical relation between these two parameters suggested by OneWeb is applied to LeoSat as an alternative to the approach taken by LeoSat in its PDR, the EPFDup limit would still be satisfied by LeoSat’s system with a margin of about 5 dB. Using LeoSat’s approach to these parameters results in a compliance margin of about 9 dB. Therefore, irrespective of which approach is taken to earth station density, LeoSat fully complies with the EPFDup limit. Should the Commission require additional information about the foregoing or otherwise in connection with the PDR, please contact the undersigned. Sincerely, /s/ Phillip R. Marchesiello Phillip R. Marchesiello Lynne M. Montgomery Counsel for LeoSat MA, Inc. 2 See ITU-R WP4A Chairman Report/364/Annex 2 – Preliminary Draft Revision of Recommendation ITU-R S.1503, Part B, § 3.3, page 11 (May 11, 2017) (independently defining ES_DENSITY and ES_DISTANCE without establishing any relationship between these parameters).


Document Created: 2017-09-19 18:07:02
Document Modified: 2017-09-19 18:07:02
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