INTERNATIONAL TELECOMMUNICATION UNION
WRC-2000
WORLD
RADIOCOMMUNICATION
CONFERENCE
Addendum 13 to
Document 34-E
27 April 2000
Original: English
ISTANBUL, 8 MAY – 2 JUNE 2000
PLENARY MEETING
Note by the Secretary-General
REVIEW AND POSSIBLE REVISION OF THE 1997 BROADCASTINGSATELLITE SERVICE PLANS FOR REGIONS 1 AND 3
STUDY TO DETERMINE THE IMPACT OF ALTERNATIVE FEEDER-LINK
BEAMS FOR AUSTRALIA
Please find attached to this document additional information to that contained in Document
WRC2000/34.
Yoshio UTSUMI
Secretary-General
Attachment: Study to determine the impact of alternative feeder-link beams for Australia
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ATTACHMENT
Director, Radiocommunication Bureau
STUDY TO DETERMINE THE IMPACT OF
ALTERNATIVE FEEDER-LINK BEAMS FOR AUSTRALIA
1
Introduction
The Administration of Australia requested at the last IRG meeting that 10 (12) channels be provided
to all Australian test points including its offshore territories for both the downlink and feeder link.
The IRG agreed to investigate the proposal and asked the Radiocommunication Bureau to perform
an additional study at the end of the basic study in order to determine the impact of the request.
After the last IRG meeting, the Administration of Australia clarified further this request. It indicated
with more details its preferences with respect to its feeder-link assignments (see section 3 below).
With respect to its downlink assignments, this Administration indicated that the assumptions taken
to carry out the feasibility study presented at that meeting were satisfactory with a small caveat
concerning the antenna patterns.
This document provides the results of a feeder-link study conducted by the Bureau, which includes
the Australian preferences for consideration by WRC-2000.
2
Methodology
In accordance with the IRG decision on the issue, at the end of the basic feeder-link feasibility
study, the modifications described in section 3 below are implemented, and MSPACE interference
analyses are conducted.
3
Technical assumptions
Bearing in mind that the Administration of Australia requested earlier not to change its assignments
of the Appendix S30A Plan, this Administration requested to use specific arrangement of beams and
channels when implementing additional feeder-link channels for Australia in the feasibility studies.
3.1
Preferred feeder-link channels
The Administration of Australia requested to use channels 1, 5, 9, 13, 17, 21 CL (or alternatively
27, 31, 35, 39, 25, 29) at the orbital position 152 E, and channels 4, 8, 12, 16, 20, 24 CL (or
alternatively 30, 34, 38, 24, 28, 32) at the orbital position 164 E.
Since the additional channels 1, 5, 9 CR and 4, 8, 12 CL were assigned to Australia at the orbital
positions 152 E and 164 E respectively in the “basic” downlink feasibility study, the feeder-link
channels 1, 5, 9 CL and 4, 8, 12 CL were used at these orbital positions respectively for the purpose
of this additional study, in addition to the Appendix S30A Plan channels assigned to the other
feeder-link beams of this Administration. It should be noted that these preferred additional channels
were not used in the “basic” feeder-link feasibility study because they would have produced
negative EPMs.
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3.2
Preferred feeder-link beams
The Administration of Australia requested to use the Appendix S30A Plan feeder-link antenna
pattern ellipses “AUS0040A” and “AUS0070A” for the creation of full “national coverage beams”
in combination with minimum size spot beams covering its offshore territories.
Consequently, for the purpose of this additional study, the beams “AUS0060G” at 152 E and
“AUS0070G” at 164 E were removed from the feeder-link feasibility study file and replaced by
two composite beams: “AUSA0000” at 152 E and “AUSB0000” at 164 E respectively (see
Annexes A and B to this document). It should be noted that it was not possible to use the fast-roll
antenna patterns (R123FR) requested by this Administration since no fast-roll antenna pattern was
adopted by the relevant ITU-R Study Group in the case of composite beams.
In addition to these composite beams, for each of the six Australian beams of the Appendix S30A
Plan (AUS00400/AUS0040A, AUS00500, AUS00600 at 152 E and AUS00700/AUS0070A,
AUS00800, AUS00900/AUS0090A at 164 E), six spot beams covering respectively the six
Australian offshore territories identified by that Administration were created and grouped with their
respective Appendix S30A Plan beam (see Annexes C and D to this document).
4
Results of the feeder-link study
An MSPACE run was performed to assess the new interference situation of the revised feeder-link
file, as described in section 3 above.
The results showed some excess of interference received by the proposed new composite beams
(i.e. –12.2 dB EPM for beam “AUSA0000” and –11.9 dB EPM for beam “AUSB0000”) and by
some of the Australian beams of the Appendix S30A Plan (i.e. –3.3 dB EPM for beam
“AUS00500”, –2.9 dB EPM for beam “AUS00700” and –3.1 dB EPM for beam “AUS0070A”).
A detailed analysis indicated that, at both orbital positions, the negative EPMs of the Australian
beams of the Appendix S30A Plan are due to additional adjacent channel interference from the
preferred channels used for the composite beams (see section 3.1 above). Considering that the
Administration of Australia indicated that for the feeder-link Australia may consider accepting
some level of negative EPMs where such EPMs are due to adjacent channel interference from other
Australian beams, no solution is proposed in this document to improve this particular situation for
the cases where the negative EPM was approximately –3 dB.
Another detailed analysis indicated that, at both orbital positions, only the test-points of the
proposed new composite beams, which are located within Australia’s mainland territory have
negative EPMs. This analysis indicated also that these negative EPMs are due to adjacent channels
transmitted from the offshore territories.
In order to resolve the low negative EPMs (e.g. –12.2 dB), the use of the same approach for the
additional channels as for the other channels of this Administration was implemented, i.e. using
several elliptical beams grouped together instead of using composite beams, as described in
Annexes E and F to this document. With this alternative option, it was then possible to use the
requested fast-roll antenna patterns (R123FR) for the beam covering Australia’s mainland territory.
With these new modifications, a new MSPACE run was performed to confirm that the feeder-link
beams and channels preferred by Australia could be accommodated into the draft feeder-link file
with no EPM more negative than –3.2 dB for the Australian beams, and without any other EPM
excess.
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5
Summary
The results of this study show that with some specific assumptions (i.e. replacement of composite
beams by elliptical beams grouped together), it is possible to accommodate into the draft feeder-link
file the feeder-link beams and channels preferred by Australia with no EPM more negative
than –3.2 dB for the Australian beams, and without any other EPM excess.
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ANNEX A
Proposed feeder-link composite beam “AUSA0000”
for the additional channels assigned to Australia at 152 E
New spot beams
New spot beams
Same ellipse as
AUS0040A
New spot beams
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ANNEX B
Proposed feeder-link composite beam “AUSB0000”
for the additional channels assigned to Australia at 164 E
New spot beams
New spot beams
Same ellipse as
AUS0070A
New spot beams
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ANNEX C
Appendix S30A Plan beams and proposed grouped spot beams
for Australia at 152 E
AUS00401*
AUS00501+
AUS00601#
AUS00405*
AUS00505+
AUS00605#
AUS00402*
AUS00502+
AUS00602#
AUS00406*
AUS00506+
AUS00606#
AUS00400*
AUS00500+
AUS00600#
AUS0040A*
AUS00404*
AUS00504+
AUS00604#
AUS00403*
AUS00503+
AUS00603#
Notes *, + or # indicate which beams are part of the same group
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ANNEX D
Appendix S30A Plan beams and proposed grouped spot beams for Australia at 164 E
AUS00701*
AUS00801+
AUS00901#
AUS00705*
AUS00805+
AUS00905#
AUS00702*
AUS00802+
AUS00902#
AUS00700*
AUS00800+
AUS00900#
AUS00706*
AUS00806+
AUS00906#
AUS0070A*
AUS0090A#
AUS00704*
AUS00804+
AUS00904#
AUS00703*
AUS00803+
AUS00903#
Notes *, + or # indicate which beams are part of the same group
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ANNEX E
Alternative elliptical beams grouped together to be used for the additional channels assigned to Australia at 152 E
AUSA0001
AUSA0002
AUSA0005
AUSA0006
AUSA0000
AUSA0004
AUSA0003
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ANNEX F
Alternative elliptical beams grouped together to be used for the additional channels assigned to Australia at 164 E
AUSB0001
AUSB0002
AUSB0006
AUSB0000
AUSB0005
AUSB0004
AUSB0003
_______________
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