Row 44 Reply to ViaS

REPLY submitted by Row 44 Inc.

Reply Comments of Row 44, Inc,

2013-02-05

This document pretains to SES-LIC-20120427-00404 for License on a Satellite Earth Station filing.

IBFS_SESLIC2012042700404_984857

                                         BEFORE THE

         Federal Communications Commission
                                WASHINGTON, D.C. 20554



In the Matter of                                      )
                                                      )
ViaSat, Inc.                                          )   File No. SES- LIC-20120427-00404
                                                      )   Call Sign E120075
Application for Authority to Operate Up to            )
4,000 Transmit/Receive Aeronautical-Mobile            )
Earth Stations in the Ka-band                         )

To: Chief, Satellite Division
    International Bureau


                           REPLY COMMENTS OF ROW 44, INC.

       Row 44, Inc. (“Row 44”), by counsel and pursuant to Section 25.154 of the

Commission’s Rules (47 C.F.R. § 25.154), hereby replies to the ViaSat, Inc. (“ViaSat”) response

filed on January 24, 2013 concerning Row 44’s initial comments in the above-captioned

application proceeding.1 Although ViaSat has submitted some additional technical and

interference coordination documentation in response to Row 44’s comments, its showing

remains incomplete, failing to demonstrate that the requested authority would provide new

service consistent with the public interest, without causing harmful interference. Rather than

illuminating the issues in a manner that would facilitate the expedited action it requests, ViaSat’s

response obscures the real questions that remain concerning its novel proposal.




1
  See Response of ViaSat, Inc., FCC File No. SES-LIC-20120427-00404 (filed January 24,
2013) (“ViaSat Response”).


                                                 -2-



         I.     ViaSat’s Coordination Showing Does Not Comply with Commission Rules
                and Established Practices.

         ViaSat’s principal responsive claim is that because it has now submitted a number of

letters from satellite operators stating generally that ViaSat’s operations “have been coordinated”

with their own satellite networks, any interference concerns must be deemed resolved.2 ViaSat

asserts that the existence of these letters “obviates the need for the Commission to independently

assess the risk of interference into those systems.”3 Submission of these letters, however, does

not eliminate the need for the Commission to assess compliance with its rules and policies

governing coordination showings, and the coordination letters that ViaSat has provided fall short

of meeting the established standard.

         It has been established both through past practice, as well as the specific requirements

that the Commission has recently adopted for Ku-band Earth Stations Aboard Aircraft, that a

proposed mobile earth station network must provide certifications from each target satellite

operator “that the proposed non-conforming earth station operation is consistent with all existing

coordination agreements with other satellite operators and that such operation will be addressed

in future coordinations.”4 The documentation that ViaSat has provided in support of its

application is voluminous, yet is largely non-responsive with respect to these specific

requirements. Theoretically, ViaSat could have produced the required coordination certifications

2
 See Letter from John P. Janka and Elizabeth R. Park, Counsel to ViaSat, to Marlene H. Dortch,
ViaSat Response at 3-4.
3
    ViaSat Response at 3. See also ViaSat Response at 7.
4
  Row 44, Inc. 24 FCC Rcd 10223, 10231 (¶ 18) (IB/OET 2009); Revisions of Parts 2 and 25 of
the Commission’s Rules to Govern the Use of Earth Stations Aboard Aircraft Communicating
with Fixed-Satellite Service Geostationary-Orbit Space Stations Operating in the 10.95-11.2
GHz, 11.45-11.7 GHz, 11.7-12.2 GHz and 14.0-14.5 GHz Frequency Bands, FCC 12-161, slip
op., Appendix C, Final Rules, at 81 (New Rule 47 C.F.R. § 25.227(b)(2)) (“ESAA R&O and
NPRM”).


                                                  -3-



in its initial application and reasonably relied on certifications from just the target satellite

operators, which include ViaSat itself, its WildBlue subsidiary, and Telesat.5 Yet even now,

after months of delay, it has still failed to produce coordination letters that squarely comply with

the straightforward regulatory requirements. For example, the certification provided by Telesat

consists mostly of a very general description of the proposed operation, and states only at the end

that “ViaSat’s operations have been coordinated with the Telesat satellite networks.”6 Notably,

although the ANIK-F2 Ka-band satellite at 111.1 W.L. is one of the three points of

communication requested by ViaSat, there are no representations by Telesat that the ViaSat

operations would be consistent with all existing coordination agreements with all adjacent

satellite systems within 6° of orbital separation or, more significantly, that it would include the

power-density levels specified by ViaSat in all of its future coordination agreements.

Accordingly, the certification is incomplete.

        This omission is troubling because, as Row 44 has emphasized from the beginning of this

proceeding, one of its principal concerns – given the relatively early stage of development of the

Ka-band orbital arc, and particularly in the development of ancillary mobile-satellite services – is

that ViaSat’s operations could have a long-term detrimental impact upon the advancement and


5
  Prior to its January 24th Supplement, ViaSat was inexplicably resistant to providing any
operator certifications, some of which were clearly available to it as early as October 2012.
Compare ViaSat Opposition to Petition to Deny of Row 44, Inc., FCC File No. SES-STA-
20120815-00751, at 4-6 (filed September 14, 2012) and ViaSat January 24th Supplement, Exhibit
1 (Engineering Certification of DirecTV, dated October 12, 2012 and Engineering Certification
from Intelsat, dated October 8, 2012). As Row 44 previously noted, early Ku-band mobile
satellite applicants were required to submit counter-signed coordination letters evidencing the
agreement of each of the affected operators. See Row 44 Comments at 7, citing., e.g., ViaSat,
Inc., 22 FCC Rcd 19964, 19969 (¶ 15) & n.31 (IB/OET 2007).
6
 ViaSat January 24th Supplement, Exhibit 1, Letter from Elisabeth Neasmith, Manager ITU and
Coordination, Office of CTO, Telesat, to International Bureau, FCC, dated December 18, 2012.


                                                 -4-



implementation of future space and earth station network proposals. Operators who might

propose to operate geostationary or non-geostationary satellite systems or ground-based

transmit/receive facilities using orbital and spectrum resources that are not currently assigned

should not be ignored. The specific certification regarding future coordination is especially

important in the context of Ka-band services, where significant swaths of orbital real estate have

not yet been brought into use.7 The core portion of the orbital arc placed at issue by ViaSat’s

Mantarray antenna extends from 85 W.L. to 71 W.L., but most of the Ka-band satellite

operators providing supporting letters have satellites that lie outside of this portion of the arc.8

There are within this range many unoccupied orbital locations that potentially would be

adversely affected by the grating lobes exhibited by ViaSat’s antenna.


       II.     ViaSat’s Technical Response Omits Key Details and Understates the
               Potential Interference Impact of Its Antenna’s Grating Lobes

       ViaSat’s response to Row 44’s technical showing also does not address fully the

legitimate concerns raised, and therefore fails to demonstrate conclusively that a system made up

of up to 4,000 Mantarray antennas will not adversely impact the Ka-band interference

environment. Instead of offering a definitive showing, ViaSat’s answers are carefully qualified.


7
  Although ViaSat has submitted coordination acknowledgements from many satellite network
operators, its submissions do not constitute an exhaustive compendium of consents even from
current industry participants that may have long term interest in developing new Ka-band
capacity, let alone represent the interests of future technology developers. For example, Inmarsat
plc is poised to launch three high capacity Ka-band satellites over the next two years under the
Inmarsat Global Xpress banner. While these spacecraft are not expected to be operated at orbital
locations within the coordination zone for the current ViaSat proposal, Inmarsat is a potential
future applicant for untapped Ka-band resources that could be placed at risk by ViaSat’s
inefficient approach to spectrum use.
8
  Those satellites that fall within the affected range are AMC-16 at 85 W.L., the Bell Canada
satellite at 82 W.L. and Hughes authorized satellite at 77.3 W.L.


                                                -5-



For example, despite its statement that “the interference environment defined by the Ka-band

rules protects all users of the band,” it can only manage to avow that it would operate its

antennas “largely within” this operating environment with “some small deviations.”9 It

maintains that it is justified in making significant “tradeoffs in antenna performance” because

these compromises allow a “low profile device that reduces drag and thus reduces aircraft fuel

usage.”10 The paramount consideration in antenna design and production, however, should not

be airline fuel economy, but the avoidance of harmful interference to other spectrum users. As

Row 44 has demonstrated in its Comments, and as further amplified in the attached Technical

Appendix, ViaSat has underestimated the impact that an antenna designed to produce grating

lobes will have in this environment.

         The Mantarray antenna’s unique horn spacing is specifically intended to eliminate

anomalous antenna lobes at zero degree antenna skew. The fact that grating lobes nonetheless

occur when the Mantarray antenna is operating free of any skew casts substantial doubt on

ViaSat’s claims that the antenna design is sound, and that repeatability of performance can be

achieved in large-scale manufacturing. The excessive grating lobes exhibited could be prevented

by reducing the horns to a width of lambda-c, consistent with industry-standard antenna design

practices. The ameliorative impact of this design correction would be even greater as higher

levels of antenna skew.11

         ViaSat also argues that the potential for mispointing occurs only when both azimuth and

elevation error are outside of three-sigma limits, and that the variable impact of these errors is


9
     ViaSat Response at 1.
10
     ViaSat Response at 3.
11
     See Technical Appendix, attached hereto, at 1-2.


                                                -6-



such that a substantial variance along one axis is unlikely to occur simultaneously with a

substantial variation along the other axis. This assertion is an over-simplification. As shown in

the attached Technical Appendix, the probability of both independent variables exceeding a 3-

sigma variance is substantially higher than ViaSat’s predictive methodology suggests, with the

result that harmful-interference-causing events are much more likely to occur at higher skew

angles than ViaSat admits in its technical demonstration. 12 ViaSat simply rejects Row 44’s

correction of its flawed assumption that calculations premised solely on azimuth or elevation

error are sufficient to characterize the full impact of antenna mispointing. In fact, pointing errors

that would exceed the 0.5 degree limit would occur for both azimuth and elevation pointing error

values well below 3-sigma, and therefore would be present a far greater portion of the time than

ViaSat’s predictive methodology suggests. ViaSat’s method of calculating and mitigating

pointing error thus substantially understates the likelihood of harmful interference to adjacent

satellite networks.




         III.   Conclusion

         For all of the foregoing reasons, Row 44 respectfully urges the Bureau to consider the

ViaSat Application carefully, particularly the potential impact of the ViaSat technical proposal

upon the future development of Ka-band services. Before the Commission takes any further

action on the application, ViaSat should be required to supplement its showing with additional




12
     See Technical Appendix, attached hereto, at 3-6.


                                              -7-



information sufficient to address the continuing deficiencies outlined herein and in Row 44’s

initial Comments.

                                             Respectfully submitted,

                                             ROW 44, INC.



                                             By:     s/ David S. Keir
                                                    David S. Keir

                                                    Lerman Senter PLLC
                                                    2000 K Street, NW, Suite 600
                                                    Washington, DC 20006-1809
                                                    (202) 429-8970

February 5, 2013                             Its Attorney


                                  Technical Appendix

ViaSat’s Mantarray Antenna Does Not Reflect “State-of-the-Art” Design

In its response, ViaSat devotes considerable discussion to defending the Mantarray
Antenna’s design and manufacturing repeatability. However, the content of ViaSat’s
Application itself contradicts its claims.

Figure 1, below, extracted from ViaSat’s Application, plots the EIRP Density for zero
degree antenna skew. The plot shows the first-order grating lobes at approximately +/-
32 degrees from center. As Row 44 stated in its Comments, the Mantarray antenna’s
unique horn spacing is specifically established for the purposes of eliminating grating
lobes in the 0 degree skew plot. The very existence of such lobes in the plot casts
doubt upon ViaSat’s claims as to the antenna’s design and repeatability of performance
in large-scale manufacturing. If the antenna possessed the integrity claimed by ViaSat,
there would be no, or very low-level, grating lobes present. As it is, the plotted grating
lobes are of a magnitude that violates the Section 25.138 EIRP mask. See 47 C.F.R.
§25.138. Considering this extensive deviation between intended design and actual
performance, no conclusion can be made that ViaSat’s antenna will achieve the claimed
satisfactory performance.

The Commission must also keep in mind that, as Row 44 has previously indicated, the
excessive grating lobe-levels of the Mantarray antenna are preventable by reducing the
horns to a width of lambda-c, vs. the Mantarray’s value of 2*lambda-c. The inferior
performance of the Mantarray Antenna is therefore neither a function of the laws of
physics nor consistent with state-of-the-art design,

In addition, the impact of the grating lobes at zero degrees skew is substantially less
than at higher skew values. The second plot below (Figure 2), also extracted from
ViaSat’s application, shows grating level exceedances at 25 skew, and also shows the
substantial asymmetric nature (~15 dB) of the Mantarray antenna grating lobes. Also,
grating lobe level variations of ~7 dB exist, for example, between ViaSat’s LHCP EIRP
spectral density plots at 28.35 GHZ and 30 GHz. These types of deficiencies originate
from the limitations of the Mantarray Antenna design. For example, in practice, the
power dividers in the antenna’s feed network will introduce a (frequency-dependent)
phase shift between the signals in two (or more) arms. These phase shifts are very
sensitive to manufacturing tolerances and, indeed, cause the significant asymmetries
observed between the left and right sections of the plots.

In summary, unavoidable fabrication tolerances will lead to variations in the antenna
patterns of different production units. The grating lobe fluctuations with significant phase


                                          ‐2‐



errors indicate that repeatability cannot be ensured and that the performance of the
measured antenna will degrade over time due to environmental effects.



Figure 1:


                                            ‐3‐



Figure 2:




Pointing Error

ViaSat misses the point of Row 44’s argument relating to pointing error. ViaSat implies
that the potential of mispointing occurs only when both the azimuth and elevation error
are both outside of the three-sigma limit, and states that a value of 7.8 e-8 percent
corresponds to the likelihood of such mispointing. To make matters worse, ViaSat’s
calculation is erroneous.

The probability of a Gaussian variable being within 3-sigma is a ratio of 0.9973. The
probability of two such independent variables exceeding 3-sigma is (1-0.9973)*(1-
0.9973), or a factor 7.3e-6, which, multiplied by 100, yields a probability of 7.3e-4
percent, not the 7.3e-8 percent ViaSat claims.

ViaSat also does not accept the significance of Row 44’s tabular listing of maximum
GSO arc pointing error values, and ignores Row 44’s correction of ViaSat’s flawed
assumption that calculations based only on azimuth or elevation errors are sufficient to
characterize mispointing. If ViaSat employed the appropriate analysis, it would show
that a violation of the 0.5 degree limit will occur for azimuth and elevation pointing error
values well below 3-sigma.


                                            ‐4‐



Further, in an effort to deflect legitimate concern regarding its antenna’s design, ViaSat
engages in a qualitative discussion suggesting a variable, inter-dependent relationship
between the Mantarray antenna’s elevation and azimuth pointing errors, where
substantial variances along one axis are less prone to occur simultaneously with
substantial variances along the other axis. However, ViaSat includes no quantitative
information defining the conditions and extent under which such trade-off effects would
occur, nor any diagrams depicting the basis for its claims.

Row 44 has performed additional analysis clarifying the significance of the mispointing
calculations provided in its initial Comments, and submits the plot below to demonstrate
the likelihood that ViaSat’s design and implementation will violate mispointing
standards. The method of calculating pointing error must, in contrast to ViaSat’s
method, consider both azimuth and elevation pointing errors and skew angle. The
equation is as follows:

    PointErrorAlongGSO = AzPointError*Cos(SkewAngle) + ElPointError*Sin(SkewAngle)

Using this equation, Row 44 analyzed ViaSat’s pointing error assuming Gaussian-
distributed values of azimuth and elevation error, using ViaSat’s stated sigma of .09 and
.45 degrees, respectively. Row 44’s analysis broke down the range of azimuth and
elevation errors into two hundred (200) discrete values each, and calculated the
statistical influence of each potential combination of azimuth and elevation error. Using
this discrete approach, Row 44 removed the influence of instances where either the
elevation error exceeded 1.35 degrees or the azimuth error exceeded 0.5 degrees.
 (That is, Row 44’s total ‘count’ of the statistics of instances where the pointing error
exceeds a given value did not include the ‘count’ of statistics of instances where the
pointing error exceeded the same, but where ViaSat would disable its transmitter).
Therefore, each trace in the plot below (Figure 3) represents the total time that the
pointing error will exceed a given value while ViaSat’s transmitter is active, compared to
the total time that ViaSat’s system is operating with either an active or inactive
transmitter.

This analysis was performed for skew values between 0 and 60 degrees (i.e., the
functional range claimed by ViaSat). The black vertical trace denotes the 0.5 degree
pointing error limit. As another reference, the light-blue vertical trace denotes the 0.2
degree pointing error limit.


                                                                            ‐5‐




Figure 3:

                                          ViaSat Ka Antenna Pointing Error Rate for Various Skew Values
                                                                     (Active Transmitter)
                   100.00%

                                                    Plots assume:                                               60 degree skew
                    90.00%                          Azimuth error sigma =.09 degrees
    e                                               Elevation error sigma =.45 degrees                          50 degree skew
    lu
     a                                              Transmitter muted for either:
     V              80.00%                          Az error>= .5 deg. or El error >= 1.35 deg.
                                                                                                                40 Degree Skew
     n
     e
     vi                                                                                                         30 Degree Skew
      G             70.00%
      g
      in                                                                                                        20 Degree Skew
       d
       e
       e
       cx           60.00%                                                                                      10 Degree Skew
        E
        r                                                                                                       0 Degree Skew
        o
        rr          50.00%
         E
         g                                                                                                      .5 Degree Pointing Error Limit
         n
         ti
          in        40.00%                                                                                      .2 Degree Pointing Error LImit
           o
           P
           f
           o        30.00%
           yt                                                                                         Pointing error greater
            ili
              b                                                                                       than .5 deg ~20% of time.
              a     20.00%
              b
              ro
               P
                    10.00%


                     0.00%
                          0.000   0.100     0.200     0.300         0.400        0.500        0.600     0.700         0.800        0.900         1.000
                                                              Magnitude of Pointing Error (deg.)



The plots portray the troubling nature of ViaSat’s approach, as the pointing error
frequently exceeds 0.5 degrees. At 30 degrees skew, the brown trace indicates that the
GSO arc pointing error will exceed 0.5 degrees ~3.5% of the time. For 40 degrees
(purple), ~9% of the time. For 50 degrees (yellow), ~15% of the time. For 60 degrees
skew (red), the .5 degree limit will be exceeded nearly ~20% of the time.

From another perspective, using Viasat’s 0.09 azimuth pointing error and a 0.45
elevation pointing error values, the probability that 0.50 pointing error is exceeded can
be computed from a normal distribution with zero mean and a standard deviation
determined for a specified skew angle. The standard deviation is computed from




where


                                            ‐6‐




In the critical skew range between 300 and 400, Table 1 provides the probability in
percent for this exceedance. These correspond to the graphical representation
developed above.

        Table 1:


          Skew angle          Probability of 0.5%
           (degrees)           exceedance (%)


               30                     3.6

               35                     6.2

               40                     9.3


In short, ViaSat’s method of calculating and mitigating pointing error substantially
understates the likelihood of harmful interference to adjacent satellite networks.

ViaSat asserts that the grating lobe exceedances are between 250 and 350 off axis, but
the labeling of the off-axis EIRP plots themselves is contradictory. Exhibit 2 of the
ViaSat January 24th Supplement labels the x axis as azimuth and the y axis as
elevation, whereas the same plot in the ViaSat application (Attachment, Figure 3) labels
the x-axis as –cos() and the y‐axis as sin(), leading to an ambiguous representation,
and an interpretation of the results of uncertain validity. Also, as the plot is offered for
only a single frequency, insufficient data is provided to permit a complete analysis for all
transmit frequencies that could either corroborate or disprove conclusively ViaSat’s
assertions regarding grating lobe exceedances.


                             TECHNICAL CERTIFICATE


       I, James B. Costello, hereby certify that I am the technically qualified person
responsible for the preparation of the technical discussion contained in the foregoing "Reply
Comments of Row 44, Inc." that I am familiar with Part 25 of the Commission's Rules (47
C.P.R., Part 25), and that I have either prepared or reviewed the technical information and
supporting facts contained herein and found them to be complete and accurate to the best of my
knowledge and belief.




February 5, 2013                       By:
                                                   James B. Costello
                                                   Vice President - Engineering
                                                   Row44, Inc.


                                CERTIFICATE OF SERVICE


       I, Sharon A. Krantzman, do hereby certify that on this 5th day of February 2013, I sent a
copy of the foregoing “Reply Comments of Row 44, Inc” via first-class mail to:

                              Daryl T. Hunter
                              ViaSat, Inc
                              6155 El Camino Real
                              Carlsbad, CA 92009

                              John P. Janka
                              Elizabeth R. Park
                              555 Eleventh Street, N.W.
                              Suite 1000
                              Washington, D.C. 20004




                                                        s/ Sharon A. Krantzman
                                                            Sharon A. Krantzman



Document Created: 2013-02-05 21:02:45
Document Modified: 2013-02-05 21:02:45

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