Attachment Exhibit A SAT-MOD-20091127-00129

Attachment Exhibit A

This document pretains to SAT-MOD-20091127-00129 for Modification on a Satellite Space Stations filing.

IBFS_SATMOD2009112700129_783987

EXHIBIT A

MODIFICATION NARRATIVE

Before the
FEDERAL COMMUNICATIONS COMMISSION
Washington, D.C. 20554

In the Matter of )
)
VIASAT, INC. ) File Nos. SAT-LOA-20070314-00051,
) SAT-MOD-20071204-00168, SAT-
Application to Modify Authorization to ) MOD-20080718-00144
Launch and Operate a Ka-Band Satellite at the )
Nominal 77º W.L. Orbital Location ) Call Sign S2737
)
)

APPLICATION FOR LICENSE MODIFICATION

ViaSat, Inc. (“ViaSat”) hereby files this application to modify ViaSat’s existing

license to launch and operate VIASAT-77 at the 77.3º W.L. orbital location to provide fixed

satellite service (“FSS”). ViaSat seeks authority to operate in the 18.8-19.3 GHz band on a non-

conforming, non-interference basis and in the 28.6-29.1 GHz band on a secondary, non-

interference basis. The attached Supplemental Technical Annex and the associated Schedule S

contain the relevant technical details.

I. BACKGROUND

On July 18, 2007, the Commission granted ViaSat a license to launch and operate

VIASAT-77, a Ka-band GSO FSS satellite at 77.3º W.L. 1 The Commission subsequently

modified that license to permit ViaSat to operate VIASAT-77 using the 28.1-28.35 GHz band on

a secondary basis. 2 Today, ViaSat is authorized to operate VIASAT-77 in the 18.3-18.8 GHz

and 19.7-20.2 GHz downlink bands and the 28.1-28.6 GHz and 29.5-30.0 GHz uplink bands.

1
Public Notice, SAT-00458, Policy Branch Information, Actions Taken, DA 07-3322 at 1
(rel. July 20, 2007).
2
Public Notice, SAT-00524, Policy Branch Information, Actions Taken, DA 08-1204 at 2
(rel. May 23, 2008).

ViaSat had previously notified the Commission that VIASAT-77 would be constructed at

ViaSat’s own risk with the capability of also operating in the 18.8-19.3 GHz and 28.6-29.1 GHz

bands. 3 In this application, ViaSat seeks authority to operate in these bands on a non-

interference basis.

II. PUBLIC INTEREST BENEFITS

Grant of authority to operate VIASAT-77 at 18.8-19.3 GHz and 28.6-29.1 GHz

would serve the public interest in several important respects. Most significantly, using these

long-fallow spectrum bands would significantly increase the capacity on the satellite and the

number of broadband consumers that the satellite can support, and also would lower the “per bit”

cost of providing service.

VIASAT-77 will provide a cost-effective means of extending high-quality

broadband service to households who simply do not have that option available today. This

system is designed to use spectrum in the most efficient manner to allow reliable, high-speed

broadband service at low per-bit transmission costs. The spectrum-efficient satellite design,

coupled with the use of spot beams and ViaSat’s innovative ground terminal hardware

technology, enable the provision of affordable broadband service that is comparable in both

speed and service quality to cable modem and DSL services. By enabling the provision of this

high quality of service to a greater number of subscribers, grant of this modification application

will enhance competition and promote the growth and development of cost-effective broadband

services.

3
SAT-MOD-20080717-00144, Exhibit D.

2

customers, and (ii) reduce the cost-per-bit of providing service, and thereby provide more cost-

effective broadband services. Grant of this waiver thus would increase the availability of

affordable high-data-rate communications services in the United States and therefore help satisfy

the demand for satellite broadband access. Moreover, because there is no operating commercial

NGSO system that uses these frequencies, grant of the waiver would allow ViaSat to make

efficient use of an unused spectrum resource.

Significantly, the VIASAT-77 satellite is designed to be able to use this spectrum

resource without causing harmful interference into any NGSO system that may be deployed in

the future, as discussed further below. Grant of the requested waiver therefore is consistent with

Commission precedent and with the Commission’s orders allocating the 18.8-19.3 GHz band

primarily for NGSO FSS use.

When the Commission established rules for licensing satellites in the 18 GHz

band, it lacked record evidence that sharing between NGSO FSS and GSO FSS operations would

be feasible in the 18.8-19.3 GHz band. The Commission thus did not broadly allow for GSO use

of the 18.8-19.3 GHz band. 9 Rather, the Commission left open the possibility that parties would

submit information demonstrating that such sharing was possible 10 and found that, in principle,

secondary use of the 18.8-19.3 GHz band would “be feasible if the stations of the secondary

service could be designed to operate without impact on the primary service.” 11 Since then, the

9
Redesignation of the 17.7-19.7 GHz Frequency Band, Blanket Licensing of Satellite
Earth Stations in the 17.7-20.2 GHz and 27.5-30.0 GHz Frequency Bands, and the
Allocation of Additional Spectrum in the 17.3-17.8 GHz and 24.75-25.25 GHz Frequency
Bands for Broadcast Satellite-Service Use, First Order on Reconsideration, 16 FCC Rcd
19808, at ¶ 29 (2001) (“We find the record in this proceeding to be insufficient to
determine whether and how GSO/FSS systems can operate on a secondary basis in
NGSO/FSS bands . . . .”).
10
Id.
11
Redesignation of the 17.7-19.7 GHz Frequency Band, Blanket Licensing of Satellite
Earth Stations in the 17.7-20.2 GHz and 27.5-30.0 GHz Frequency Bands, and the

5

Commission has entertained multiple requests for GSO use, but only a few of them contained an

adequate showing that sharing was possible. 12 In granting each of Northrop Grumman Space &

Mission Systems Corporation (“Northrop Grumman”) and AtContact a waiver of Section 2.106

to permit the operation of GSO FSS satellites at 18.8-19.3 GHz on a non-conforming, non-

interference basis, the Commission found that each applicant submitted a sufficient “quantitative

demonstration” of how its GSO FSS satellites would operate in these bands while protecting the

primary NGSO FSS systems. 13 Below, ViaSat provides a similar quantitative showing of how it

will protect primary NGSO users.

B. Non-Interference Showing for the 18.8-19.3 GHz and 28.6-29.1 GHz
Bands

As demonstrated in the Supplemental Technical Annex, neither ViaSat’s

operations in the 28.6-29.1 GHz band pursuant to the secondary GSO FSS allocation, nor its

operations in the 18.8-19.3 GHz band on a non-conforming, non-interference basis, will cause

harmful interference to any NGSO FSS system (including those that are similar to the design of

the previously authorized Northrop Grumman and AtContact systems). 14 The VIASAT-77

Allocation of Additional Spectrum in the 17.3-17.8 GHz and 24.75-25.25 GHz Frequency
Bands for Broadcast Satellite-Service Use, Report and Order, 15 FCC Rcd 13430, at ¶ 57
(2000).
12
See Northrop Grumman Space & Mission Systems Corporation, Order and Authorization,
DA 09-428, at ¶¶ 86, 88 (rel. Feb. 23, 2009) (“Northrop Grumman Order”); contactMEO
Communications, LLC, Order and Authorization, DA 06-864, at ¶¶ 33, 35 (rel. Apr. 14,
2006) (“AtContact Order”). Compare, e.g., EchoStar Satellite LLC, 19 FCC Rcd 7846,
at ¶¶ 19-20 (2004) (rejecting EchoStar’s request to operate GSO FSS system in 18.8-19.3
GHz band because EchoStar had failed to demonstrate that there would be a low potential
for interference into any NGSO system).
13
Northrop Grumman Order at ¶¶ 86, 88; AtContact Order at ¶¶ 33, 35.
14
Northrop Grumman surrendered its system license on March 26, 2009, and AtContact
surrendered its NGSO authorization on February 6, 2009. See AtContact Letters; Letter
from Stephen D. Baruch, counsel to Northrop Grumman Space & Mission Systems
Corporation, to Marlene H. Dortch, Secretary, FCC, Re: Surrender of Space Station and
Satellite System Authorizations (File Nos. SAT-LOA-19970904-00080, et seq., Call
Signs S2254, S2255, S2256, S2257, and S2258).

6

satellite employs technology that will allow it to operate in a manner that protects NGSO FSS

systems in the 18.8-19.3 GHz and 28.6-29.1 GHz bands from harmful interference, while still

maintaining service in other frequency bands. In this respect, ViaSat notes that it had negotiated

a coordination agreement with AtContact after establishing to AtContact’s satisfaction that

ViaSat’s technology and VIASAT-77’s novel satellite design would protect the AtContact

system from harmful interference.

Specifically, the satellite has been designed with the capability to cease operations

in the 18.8-19.3 GHz downlink band and in the associated 28.6-29.1 GHz uplink band in any

spot beams where the predicted physical alignment of either (i) the VIASAT-77 satellite and an

earth station communicating with an NGSO space station, or (ii) an NGSO space station and an

earth station communicating with the VIASAT-77 satellite, is such that the angular separation

between operational links of the two satellite networks would be equal to or less than a specified

minimum line-of-sight separation angle. In that case, and for the short duration of the event, the

affected VIASAT-77 satellite spot beam will continue providing service in a portion of the

currently-authorized spectrum bands—namely, 18.3-18.8 GHz and 28.1-28.6 GHz.

In the Supplemental Technical Annex, ViaSat demonstrates that the VIASAT-77

satellite’s operations in the 18.8-19.3 GHz and 28.6-29.1 GHz bands will not interfere with

primary NGSO operations. As part of this quantitative demonstration, ViaSat analyzed the

NGSO systems of AtContact and Northrop Grumman and determined that the calculated

interference-to-noise ratio based on worst case scenarios is -20.4 dB, which corresponds to a

ΔT/T of only 0.92%. This level is well below the 6% ΔT/T threshold that triggers coordination

between satellite systems under the ITU Radio Regulations, and which the Commission

considered in finding that GSO use of these bands by Northrop Grumman and AtContact would

7

not cause harmful interference to other NGSO systems. 15 Moreover, ViaSat’s technical showing

contains the same type of quantitative data provided by Northrop Grumman and AtContact and

relied upon by the Commission when it granted those licensees authority to operate GSO

satellites in the 18.8-19.3 GHz and 28.6-29.1 GHz bands on a non-interference basis. 16

ViaSat commits to abide by the terms of any coordination agreements that it may

enter into with NGSO system operators, and otherwise will cease operations in the 18.8-19.3

GHz and 28.6-29.1 GHz bands in the unlikely event that it does cause harmful interference into

NGSO FSS operations. ViaSat will also accept interference that it may receive from NGSO FSS

operations in these bands.

C. Cross Polarization Isolation Waiver

With respect to the 18.8-19.3 GHz and 28.6-29.1 GHz frequencies that are the

subject of this application, ViaSat requests a waiver of the requirement that space station

antennas in the FSS be designed to meet the cross-polarization isolation threshold specified in

the Commission’s rules. As discussed further in the Supplemental Technical Annex, the

VIASAT-77 satellite will have a small cross-polarization shortfall in the satellite receive

antenna, which will have no adverse affect on the operation of other satellite networks. Grant of

this waiver is consistent with the Commission’s grant of the same waiver request with respect to

this satellite in a previous modification application. 17 The instant modification application does

not seek to change the cross-polarization isolation of the licensed satellite.

15
Northrop Grumman Order at ¶ 86; AtContact Order at ¶ 33.
16
The non-interference analyses provided by Northrop Grumman and AtContact for each of
their networks of four GSO satellites using the NGSO primary bands are equally
applicable to a single GSO satellite.
17
See IBFS File No. SAT-MOD-20080718-00144, Conditions of Authorization ¶ 2
(granted Mar. 25, 2009).

8

IV. REVISED OWNERSHIP INFORMATION

To supplement the ownership information provided in the Modification filing,

ViaSat adds to the list of Officers and Senior Management, Thomas E. Moore, Senior Vice

President. Mr. Moore can be reached c/o ViaSat, Inc., 6155 El Camino Real, Carlsbad, CA

92009.

V. WAIVER PURSUANT TO SECTION 304 OF THE COMMUNICATIONS
ACT

In accordance with Section 304 of the Communications Act of 1934, as amended,

ViaSat hereby waives any claim to the use of any particular frequency or of the electromagnetic

spectrum as against the regulatory power of the United States because of the previous use of the

same, whether by license or otherwise.

9

VI. CONCLUSION

For the foregoing reasons, granting ViaSat’s request to modify its Ka-band

satellite authorization at the nominal 77° W.L. location to use the 18.8-19.3 GHz and 28.6-29.1

GHz frequency bands on a non-interference basis will serve the public interest, convenience and

necessity. ViaSat respectfully requests that the Commission act promptly to grant this

modification application.

Respectfully submitted,

/s/
John P. Janka
Elizabeth R. Park
Latham & Watkins LLP
555 Eleventh Street, N.W.
Suite 1000
Washington, D.C. 20004
Telephone: (202) 637-2200

Counsel for ViaSat, Inc.

10

Supplemental Technical Annex

A.1 SCOPE AND PURPOSE

The purpose of this Annex is to describe the technical and operational characteristics of the 28.6-
29.1 GHz and 18.8-19.3 GHz bands of the VIASAT-77 satellite. ViaSat has previously informed
the Commission that the VIASAT-77 satellite would be constructed with the capability of
operating in these bands; however ViaSat did not seek Commission authorization to use the bands
at that time 1 .

This Annex provides the technical information relating to the requested modification and is
intended to supplement the information regarding the VIASAT-77 satellite previously submitted to
the Commission in approved license and license modification applications. The substance of this
modification application coupled with the structure of this Annex and the Schedule S form make it
necessary to reiterate certain information previously provided to the Commission. Any Part 25
requirements not included in this Annex or the associated Schedule S form have been previously
provided to the Commission and have not changed.

A.2 GENERAL DESCRIPTION

The VIASAT-77 satellite at 77.3° W.L. will provide Ka-band services to CONUS, Puerto Rico,
the U.S. Virgin Islands and portions of Canada and Mexico. The satellite will operate in the
28.1-29.1 GHz and 29.5-30.0 GHz bands (Earth-to-space) and the 18.3-19.3 GHz and 19.7-20.2
GHz bands (space-to-Earth). The satellite network will provide service to small user antennas.
In addition, a limited number of larger gateway antennas will be employed. The gateway
antennas will have the capability of transmitting in any channel within the 28.1-29.1 GHz and

1
See SAT-MOD-20080718-00144.

1

29.5-30.0 GHz bands. Uplink transmissions from the small user terminals will be restricted to
the 28.35-29.1 GHz and 29.5-30.0 GHz bands.

The satellite utilizes a bent-pipe architecture with asymmetric forward (gateway-to-subscriber)
and return (subscriber-to-gateway) links. Forward links consist of a single TDM 500 MHz wide
carrier (416.67 Msym/s), while the return links use MF-TDMA with a variety of bandwidths/data
rates employed. The network uses adaptive coding and modulation to combat rain fades. That
is, the modulation type, amount of coding and/or user data rate is dynamically varied to meet the
link requirements during rain events (in addition to employing uplink power control). The
forward links vary between 16-APSK, 8PSK and QPSK modulations, depending on the amount
of rain fade, while the return links use 8PSK, QPSK and BPSK modulation schemes.

A.3 SPACE STATION TRANSMIT AND RECEIVE CAPABILITY

ViaSat has previously provided the Commission with the characteristics of the transmit and
receive beams in terms of each beam’s capabilities, their locations and gain contours 2 for the
28.1-28.6 GHz, 29.5-30 GHz, 18.3-18.8 GHz and 19.7-20.2 GHz bands. These characteristics
apply equally to the 28.6-29.1GHz and 18.8-19.3 GHz bands, and thus, are not changed by this
modification application. The proposed addition of the 28.6-29.1 GHz and 18.8-19.3 GHz
frequency bands would add capacity to some (but not all beams), but does not affect the
technical beam characteristics already approved by the Commission. The beams that would be
able to utilize these additional bands are identified in the associated Schedule S.

A.4 FREQUENCY AND POLARIZATION PLAN

The VIASAT-77 satellite’s frequency plan for normal operating mode is given in Table A.4-1,
indicating channel center, polarization and bandwidth. Circular polarization is used on both the
uplink and downlink with the downlink polarization being orthogonal to the uplink polarization.

2
See SAT-AMD-20081203-00220.

2

The satellite will employ a four-frequency re-use pattern such that any channel is re-used multiple
times by a combination of polarization and spatial isolation. This satisfies the requirements of
§25.210(d) of the Rules.

Table A.4-1. Frequency Plan (Normal Mode)
Uplink Center Downlink Center
Bandwidth
Frequency Polarization Frequency Polarization
(MHz)
(MHz) (MHz)
28600 RHCP, LHCP 18800 LHCP, RHCP 1000
29750 RHCP, LHCP 19950 LHCP, RHCP 500

As explained in section A.7, the 1000 MHz channel, which supports two 500 MHz carriers, will
be reduced to a single 500 MHz channel (supporting one 500 MHz carrier) in the event that there
is a need to cease operating in a portion of the assigned spectrum to protect an NGSO network.
During the short period of time that the reduced bandwidth mode is in use, the frequency plan is
represented by Table A.4-2.

Table A.4-2. Frequency Plan (Reduced Bandwidth Mode)
Uplink Center Downlink Center
Bandwidth
Frequency Polarization Frequency Polarization
(MHz)
(MHz) (MHz)
28350 RHCP, LHCP 18550 LHCP, RHCP 500
29750 RHCP, LHCP 19950 LHCP, RHCP 500

The transponder bandwidth configuration provided in the Schedule S form is for the normal
mode configuration shown in Table A.4-1 above.

A.5 PREDICTED RECEIVER AND TRANSMITTER CHANNEL FILTER
RESPONSE CHARACTERISTICS

The predicted receiver and transmitter frequency responses of each 500 MHz or 1000 MHz
channel, as measured between the receive antenna input and transmit antenna, fall within the

3

limits shown in Table A.5-1 below. In addition, the frequency tolerances of §25.202(e) and the
out-of-band emission limits of §25.202(f) (1), (2) and (3) will be met.

Table A.5-1: Predicted Channel Receiver and Transmitter Frequency Responses
Frequency Receiver Frequency Receiver Frequency Transmit Frequency Transmit Frequency
Rx/Tx (MHz) Response (dB) Response (dB) Response (dB) Response (dB)
(without NGSO) (with NGSO) (without NGSO) (with NGSO)

28000/18200 <-20.0 <-20.0 <-20.0 <-20.0
28100/18300 > -3.0 >-3.0 >-3.0 >-3.0
28200/18400 > -1.7 >-2.0 >-1.5 >-1.5
28300/18500 > -1.5 >-1.7 >-0.75 >-0.75
28400/18600 >-1.5 >-1.5 >-0.5 >-0.5
28500/18700 >-1.7 >-1.5 >-0.5 >-0.5
28600/18800 >-3.0 >-1.5 >-0.5 >-0.5
28700/18900 <-20.0 >-1.5 >-0.5 >-0.5
28800/19000 <-20.0 >-1.5 >-0.5 >-0.5
28900/19100 <-20.0 >-1.7 >-0.5 >-0.5
29000/19200 <-20.0 >-2.0 >-0.5 >-0.5
29100/19300 <-20.0 >-3.0 >-0.5 >-0.5
29200/19400 <-20.0 <-20.0 N/A N/A
29300/19500 <-20.0 <-20.0 N/A N/A
29400/19600 <-20.0 <-20.0 N/A N/A
29500/19700 >-3.0 <-20.0 >-0.5 >-0.5
29600/19800 >-1.7 <-20.0 >-0.5 >-0.5
29700/19900 >-1.5 <-20.0 >-0.5 >-0.5
29800/20000 >-1.5 <-20.0 >-0.75 >-0.75
29900/20100 >-1.7 <-20.0 >-1.5 >-1.5
30000/20200 >-3.0 <-20.0 >-3.0 >-3.0
30100/20300 <-20.0 <-20.0 <-20.0 <-20.0

Note: “N/A” indicates that transmit frequency response is not applicable because signal is
attenuated by the input frequency response.

4

A.6 POWER FLUX DENSITY AT THE EARTH’S SURFACE

§25.208(c) contains PFD limits that apply in the 18.3-18.8 GHz band. The PFD limits of
§25.208(c) are as follows:

• -115 dB(W/m2) in any 1 MHz band for angles of arrival between 0 and 5 degrees above the
horizontal plane;
• -115+(δ-5)/2 dB(W/m2) in any 1 MHz band for angles of arrival δ (in degrees) between 5
and 25 degrees above the horizontal plane; and
• -105 dB(W/m2) in any 1 MHz band for angles of arrival between 25 and 90 degrees above
the horizontal plane.

In addition, §25.208(d) contains PFD limits that apply in the 18.6-18.8 GHz band produced by
emissions from a space station under assumed free-space propagation conditions as follows:

• -95 dB(W/m2) for all angles of arrival. This limit may be exceeded by up to 3 dB for no
more than 5% of the time.

§25.208 does not contain any PFD limits that apply in the 18.8-19.3 GHz band for GSO satellite
networks, however it is noted that Article 21 of the ITU Radio Regulations does include PFD
limits applicable to GSO satellites using the 18.8-19.3 GHz band. The ITU limits are identical to
those in §25.208(c).

Compliance with the applicable FCC and ITU PFD limits is demonstrated below using a simple
worst-case methodology. The maximum downlink EIRP that the VIASAT-77 satellite can
transmit is 67 dBW in 500 MHz. The shortest distance from the satellite to the Earth is 35,786 km,
corresponding to a spreading loss of 162.06 dB. Therefore the maximum possible PFD at the
Earth’s surface could not exceed -95.1 dBW/m2 in this 500 MHz (i.e., 67 -162.06). When the
system is operating in normal mode (i.e., using a 1000 MHz channel in the 18.3-19.3 GHz and
28.1-29.1 GHz frequencies), the two 500 MHz carriers within the 1000 MHz channel will each
meet the PFD performance described here. Allowing for the use of digital modulation with an
almost flat spectrum, the corresponding maximum PFD at an elevation angle of 90° measured in a
1 MHz band would not exceed -122.1 dBW/m2. The -122.1 dBW/m2/MHz level is less than the -

5

115 dBW/m2/MHz PFD limit value that applies at elevation angles of 5° and below. Therefore,
compliance with the PFD limits is assured.

A.6.1 Frequency Bands Not Subject to §25.138

This section demonstrates that uplink transmissions in the 28.6-29.1 GHz bands and downlink
transmissions in the 18.8-19.3 GHz band are two-degree compatible.

Currently there are no operational GSO Ka-band satellites that use the 28.6-29.1 GHz and 18.8-
19.3 GHz bands within two degrees of the 77.3º W.L. location. 3 Therefore, in order to
demonstrate two-degree compatibility, the transmission parameters of the VIASAT-77 satellite
have been assumed as both the wanted and victim transmissions.

Table A.6-2 provides a summary of the uplink and downlink transmission parameters. These
parameters were derived from the VIASAT-77 link budgets that are embedded in the Schedule S
form included with this modification application and were used in the interference analysis. The
interference calculations assumed a 1 dB advantage for topocentric-to-geocentric conversion, all
wanted and interfering carriers are co-polarized and all earth station antennas conform to a
sidelobe pattern of 29-25 log(θ). The C/I calculations were performed on a per Hz basis.

Table A.6-3 shows the results of the interference calculations in terms of the overall C/I margins.
The table is provided in a format similar to that of the output of the Sharp Adjacent Satellite
Interference Analysis program. It can be seen that the C/I margins are positive in all cases.

Table A.6-2. VIASAT-77 transmission parameters.

3
The Commission’s database includes a pending modification application by AtContact to move its authorization
for a GSO satellite at the 34º E.L. location to the 77º W.L. location. However, AtContact has declared its intent
to surrender its authorization at 34º E.L. Therefore, AtContact’s pending modification for orbital reassignment
to 77º W.L. is moot.

6

Tx E/S Uplink Rx E/S
Emission Bandwidth Downlink EIRP C/I Criterion
Carrier ID Gain EIRP Gain
Designator (MHz) (dBW) (dB)
(dBi) (dBW) (dBi)
1 500MG7D 500 64.6 75.0 62.0 49.3 20.3
2 500MG7D 500 64.6 75.0 62.0 40.7 13.6
3 500MG7D 500 64.6 75.0 62.0 40.7 7.2
4 6M25G7D 6.25 44.1 48.6 39.2 61.1 16.2
5 3M13G7D 3.125 44.1 48.6 36.2 61.1 14.9
6 1M57G7D 1.563 44.1 48.6 33.1 61.1 9.9
7 782KG7D 0.7813 44.1 46.4 30.1 61.1 8.7
8 25M0G7D 25 64.6 67.3 45.2 61.1 20.8

7

Table A.6-3. Summary of the overall C/I margins (dB).

Interfering Carriers
Carrier ID 1 2 3 4 5 6 7 8
1 8.5 8.5 8.5 8.5 6.5 4.1 3.4 11.5
2 6.7 6.7 6.7 9.7 9.0 7.9 7.6 10.4
Wanted Carriers

3 13.0 13.0 13.0 16.1 15.4 14.3 13.9 16.7
4 17.6 17.6 17.6 7.4 4.4 1.4 0.6 14.8
5 20.2 20.2 20.2 11.6 8.7 5.8 4.9 18.7
6 26.0 26.0 26.0 19.5 16.6 13.7 12.9 25.9
7 27.4 27.4 27.4 21.5 18.7 15.8 14.9 27.7
8 15.9 15.9 15.9 14.2 11.9 9.2 8.4 18.3

A.7 SHARING WITH NGSO FSS IN THE 28.6-29.1 GHZ AND 18.8-19.3 GHZ BANDS

While the 28.6-29.1 GHz and 18.8-19.3 GHz bands are allocated internationally for GSO and
NGSO use on a co-primary basis, these bands are allocated to NGSO FSS on a primary basis in
the U.S. Table of Allocations. The U.S. Table allocates the 28.6-29.1 GHz band to GSO FSS on
a secondary basis, while the 18.8-19.3 GHz band has no current GSO FSS allocation. ViaSat
proposes to serve the United States using the 28.6-29.1 GHz band on a secondary, non-
interference basis, and the 18.8-19.3 GHz band on a non-conforming, non-interference basis, and
thus, requests a waiver of Section 2.106 of the FCC’s rules to permit the use of the 18.8-19.3
GHz band on the VIASAT-77 satellite. The FCC granted such a waiver to AtContact and to
Northrop Gumman Space & Mission Systems Corporation (“NGST”) for the GSO spacecraft in
their respective systems. 4 The non-interference analysis for that network of GSO satellites using
the NGSO primary bands is equally applicable to ViaSat’s single GSO satellite, as demonstrated
below. This analysis demonstrates that the operations of VIASAT-77 will protect from harmful

4
See Northrop Grumman Space & Mission Systems Corporation, Order and Authorization, DA 09-428, at ¶¶ 86,
88 (rel. Feb. 23, 2009); contactMEO Communications, LLC, Order and Authorization, DA 06-864, at ¶ 35
(2006).

8

interference the HEO satellite systems previously licensed to AtContact and NGST. 5 The
VIASAT-77 spacecraft employs technology that will allow it to operate in a manner that will
protect these and any other NGSO FSS systems from harmful interference in the 18.8-19.3 GHz
and 28.6-29.1 GHz bands. ViaSat was able to negotiate a coordination agreement with
AtContact after establishing to AtContact’s satisfaction that this technology and VIASAT-77’s
novel satellite design would ensure that AtContact’s system is protected from harmful
interference.

The United States submitted to the ITU a study regarding frequency sharing among multiple
NGSO FSS systems in the Ka band frequencies in which it determined that frequency sharing
between two NGSO FSS systems is feasible if the minimum topocentric line-of-sight (“TLOS”)
angular separation between the satellites is 7º. 6 Subsequently, the FCC adopted a rule regarding
default procedures for avoidance of in-line interference events for NGSO FSS satellites in the Ka
band. The rule provides a 10º TLOS angular separation threshold for coordination requirements
for NGSO satellites. 7

Sharing with NGSO FSS in the 28.6-29.1 GHz and 18.8-19.3 GHz bands will be accomplished
by ensuring that both ground earth stations and the VIASAT-77 spacecraft disable operations in
the 28.6-29.1 GHz uplink band (and thus the corresponding 18.8-19.3 GHz downlink band)
when conditions warrant. The specific characteristics of each proposed NGSO system must be
evaluated prior to becoming operational in order to determine the minimum allowable TLOS
angular separation between the VIASAT-77 satellite and the proposed NGSO system.

5
Although NGST has surrendered its system license and AtContact has surrendered the NGSO portion (as well
as certain GSO portions) of its license, ViaSat includes these systems in its analysis to demonstrate that systems
like AtContact and NGST’s previously licensed systems would be protected from harmful interference from
ViaSat’s system.
6
ITU-R Working Party 4A (Document 4A/287) (1999).
7
47 C.F.R. § 25.261(b).

9

Both of the two NGSO systems currently identified, AtContact and NGST, were authorized to
use identical HEO constellations of three satellites with orbital characteristics as defined in Table
A.7-1. The sharing analyses submitted by NGST and AtContact each state that the minimum
operational altitude of the HEO spacecraft is 16,000 km. Additionally, the minimum operational
elevation angle from the NGST or AtContact earth stations to the HEO satellites is given as 10°.

Parameters ViaSat System NGST / AtContact
Systems
Orbital Parameters
• # Satellites • 1 satellite at 77.3° W • 3 satellites
• # Planes • N/A • 3 planes
• # Satellites / Plane • N/A • 1
• Inclination Angle • N/A • 63.4°
• Apogee • N/A • 39352 km
• Perigee • N/A • 1111 km
• Period • N/A • 43064 s
Minimum Operational Altitude N/A 16000 km
Minimum Operational ES 5° 10°
Elevation Angle
Frequency
• Uplink • 28.6 – 29.1 GHz • 28.6 – 29.1 GHz
• Downlink • 18.8 – 19.3 GHz • 18.8 – 19.3 GHz
Earth Terminal Antenna Size 0.67 m & 1.2 m 0.7 m & 1.2 m
Earth Station Tx EIRP Density -12.5 dBW/Hz -14.15 dBW/Hz
Satellite Rx Antenna Gain 53.2 dBi 46.5 dBi
Satellite Rx System Noise Temp 1230 K 504 K
Satellite Tx EIRP Density -20.0 dBW/Hz -18 dBW/Hz
Earth Station Rx System Noise 224 K 315 K
Temperature
Table A.7-1

After examining the range of potential earth station locations in the service area for VIASAT-77,
the minimum predicted TLOS angular separation between either (i) the VIASAT-77 and an earth
station communicating with an NGSO space station, or (ii) an NGSO space station and an earth
station communicating with VIASAT-77, given the system characteristics in Table A.7-1, has
been determined to be 32.6°. However, to be conservative, the following interference calculation

10

shows the expected interference degradation to the NGST or the AtContact system due to
operation of the ViaSat system at an angular separation of 30°.

Earth Station Location
• Latitude • 70° N
• Longitude • Any

Parameters ViaSat System NGST / AtContact
Systems
UpLink
Frequency Band 28.85 GHz 28.85 GHz
Orbital Location 77.3° WL HEO
E/S Uplink EIRP Density -12.5 dBW/Hz -14.15 dBW/Hz
E/S Antenna Gain 44.1 dBi 49.3 dBi
TLOS Angular Separation 30° 30°
Off-Axis EIRP density -61.5 dBW/Hz -68.4 dBW/Hz
Slant Range 40957.5 km 16000 km
Path and Atmospheric Losses 215.1 dB 206.9 dB
Satellite Receive Antenna Gain 53.2 dBi 46.5 dBi
System Noise Temperature 1230 K 504.0 K
Thermal Noise Density, No -197.7 dBW/Hz -201.6 dBW/Hz
Interference Noise Density, Io -230.3 dBW/Hz -222.0 dBW/Hz
Io/No -32.9 dB -20.4 dB
Uplink Degradation 0.0024 dB 0.0400 dB
ΔT/T 0.0554 % 0.916 %
Downlink
Frequency Band 19.05 GHz 19.05 GHz
Satellite EIRP Density -20.0 dBW/Hz -18.0 dBW/Hz
Path and Atmospheric Losses 211.29 dB 203.12 dB
Off-axis Antenna Gain -4.93 dBi -4.93 dBi
E/S System Noise Temperature 224 K 315 K
Thermal Noise Density -205.1 dBW/Hz 203.6 dBW/Hz
Interference Noise Density -234.2 dBW/Hz -228.1 dBW/Hz
Io/No -29.12 dB -24.43 dB
Downlink Degradation 0.0053 dB 0.0157 dB
ΔT/T 0.123 % 0.360 %
Table A.7-2

The results show that both the AtContact and NGST systems are adequately protected. The
calculated interference-to-noise ratio based on worst case scenarios is -20.4 dB, which

11

corresponds to a ΔT/T of 0.92%. This value is well below the 6% ΔT/T threshold that triggers
coordination between satellite systems under the ITU Radio Regulations.

Consistent with the default rule for NGSO/NGSO in-line events in § 25.261(b), the VIASAT-77
satellite and ground segment have been designed to be capable of protecting future NGSO
systems whose orbital characteristics may result in TLOS angular separations of 10° or less.
Thus, even if an NGSO system is brought into operation with an architecture that results in a
separation angle of 10º or less, ViaSat’s system will still successfully protect such an NGSO
system from harmful interference. ViaSat will coordinate with future NGSO operators to
determine the minimum required TLOS angular separation necessary to protect each system.

The VIASAT-77 spacecraft has been designed with the capability to disable operation in the
18.8-19.3 GHz and 28.6-29.1 GHz bands upon receipt of appropriate ground command signals –
a capability that provides a technical basis for the coordination agreement between ViaSat and
AtContact. Each spot beam is individually controllable. When operations cease in these bands
in an affected spot beam, the 1000 MHz channel is reduced to a 500 MHz channel in the 18.3-
18.8 GHz and 28.1-28.6 GHz frequencies, with services in the affected spot beam continuing in
this single 500 MHz carrier. During these events, the power and power density levels in the
18.3-18.8 GHz and 28.1-28.6 GHz bands comply with the applicable limits, as discussed above
in this Technical Annex.

A processor at the central control site for the satellite will determine the predicted orbits of the
victim NGSO satellites through the use of well understood algorithms and regularly updated 2-
line element set data obtained from reliable on-line sources and directly from the NGSO operator
itself. The processor will then calculate the current TLOS angular separation for earth stations in
each of the spot beams.

When the angular separation is predicted to be equal to, or below the desired value, the earth
stations in the affected spot beam will be commanded to stop transmitting in the 28.6-29.1 GHz
band and, similarly, the VIASAT-77 satellite will be commanded to switch off operations in the

12

18.8-19.3 GHz and 28.6-29.1 GHz bands for the spot beam in question. When the angular
separation increases to a value above the cut-off threshold, normal operation is restored to the
earth stations and satellite.

Note that the normal or fail-safe condition on the VIASAT-77 spacecraft is to disable operations
in the 18.8-19.3 GHz and 28.6-29.1 GHz bands to protect NGSO networks.

A.8 WAIVER REQUEST

A.8.1 Section 25.210(i)

With respect to the 18.8-19.3 GHz and 28.6-29.1 GHz frequencies that are the subject of this

application, ViaSat requests a waiver of the requirement in Section 25.210(i) of the

Commission’s rules, which requires that space station antennas in the FSS be designed to meet a

cross-polarization isolation of 30 dB within the primary coverage area of the antenna. The

VIASAT-77 satellite’s uplink spot beam receive antennas (for all spot beams) provide a

minimum cross-polarization of 26 dB. In support of its requested waiver, ViaSat notes that the

small cross-polarization shortfall is in the uplink direction only and therefore will have no

adverse affect on other satellite networks. 8 Further, the satellite’s cross-polarization isolation

performance has been fully taken into account in the design of the link budgets for the services

that the satellite will provide. The link budgets are sufficiently robust to compensate for the

negligible effect of the slightly reduced cross-polarization isolation performance. Grant of the

requested waiver is also consistent with prior Commission decisions granting similar waivers of

8
Receive cross-polarization interference is an intra-system design issue, and does not affect other satellite
networks.

13

Section 25.210(i), including the Commission’s grant of this same waiver request for the

VIASAT-77 satellite.9 This aspect of satellite will not be changed by the license modification

requested in this application to merely operate in additional frequencies.

___________________________________

9
See IBFS File No. SAT-MOD-20080718-00144, Conditions of Authorization ¶ 2 (granted Mar. 25, 2009); see
also, EchoStar Satellite Operating Corporation, Application for Authority to Operate the EchoStar 9 Satellite in
the Lower 500 MHz Portion of the Ka-band Frequencies at the 121º W.L. Orbital Location, File Nos. SAT-
MOD-20060830-00092, SAT-STA-20050608-00116, Order and Authorization, DA 06-2590 ¶¶ 7-8 (rel. Dec.
22, 2006).

14

CERTIFICATION OF PERSON RESPONSIBLE FOR PREPARING
ENGINEERING INFORMATION

I hereby certify that I am the technically qualified person responsible for preparation of

the engineering information contained in this pleading, that I am familiar with Part 25 of the

Commission’s rules that I have either prepared or reviewed the engineering information

submitted in this pleading, and that it is complete and accurate to the best of my knowledge and

belief.

/s/
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
Stephen D. McNeil
Telecomm Strategies Canada, Inc.
Ottawa, Ontario, Canada
(613) 270-1177

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Document Created: 2009-11-27 20:52:06
Document Modified: 2009-11-27 20:52:06

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