Coordination For Satellite Networks

Presentation / Coordination For Satellite Networks

Date Submitted: 02 October 2001

Written by RPC Telecommunications. Website:

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Covers topics including Satellite Coordination Background, Satellite - Terrestrial and Satellite - Satellite Coordination and the role of the ITU in coordination.

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 Printable Version
-Section 1
Satellite Coordination Background
-Section 2
What Is Coordination?
-Section 3
Key Issues
-Section 4
Frequency Allocations
-Section 5
Satellite - Terrestrial Coordination
-Section 6
Satellite - Satellite Coordination
-Section 7
Satellite - Satellite Coordination
Satellite Coordination Requirements

The satellite coordination procedure is described in Article S9 of the Radio Regulations. Before bringing an assignment in a satellite network into use an administration must undertake the S9 coordination procedure:

  • Advance publication
  • Coordination
  • Notification

These are in parallel to the satellite-terrestrial coordination already described.

Advance Publication
Between 2 and 5 years before bringing into use an administration planning a new satellite network must initiate the Advance Publication. For networks subject to coordination the advance publication is very general and contains little information. For networks not subject to coordination the advance publication is very detailed and contains specific information about the network implementation. The API is mainly for the purposes of informing all administrations of developments in the use of space radiocommunications.
Coordination Request
For the cases requiring detailed coordination the administration must follow the API with the coordination request. This is a detailed description of the network parameters to sufficient detail to allow interference calculations to be made. This must be submitted not earlier than 6 months after the receipt of the API data. This defines the “priority” (date of protection) of the network. Administrations must object within 4 months of publication or lose the right to future objection.
The Need To Coordinate
The right of coordination with a new network depends mainly on three things:
  • the other network is already either registered in the MIFR or it has begun the process of coordination
  • the other network is in conformity with the Radio Regulations
  • either the increase in the equivalent noise temperature due to the new network relative to the noise temperature present in the absence of interference (DT/T), calculated in accordance with Appendix S8 of the RR, is more than 6 %, or in certain frequency bands the orbital separation between the networks is less than a trigger value (the so-called "coordination arc")
Coordination Arc
Coordination is required in the bands:

3400- 4200 MHz, 5725- 5850 MHz (Region 1) and 5850- 6725 MHz where the trigger orbital separation is 10º or less

10.95- 11.2 GHz, 11.45- 11.7 GHz, 11.7- 12.2 GHz (Region 2), 12.2- 12.5 GHz (Region 3), 12.5- 12.75 GHz (Regions 1 and 3), 12.7- 12.75 GHz (Region 2) and 13.75- 14.5 GHz where the trigger orbital separation is 9º or less

17.7- 20.2 GHz and 27.5- 30 GHz where the trigger orbital separation is 8º or less

DeltaT/T - Appendix S8 Procedure
This procedure estimates the likely interference caused by an "interfering" network by estimating the increase in system noise temperature that this network might cause to a "wanted" network.




Since the noise temperature of the "wanted" network is known then the value of DeltaT/T is easily calculated. If the value of DeltaT/T exceeds 6% then coordination is required. If the value of DeltaT/T is 6% or less then coordination is not required. In some cases the uplink and downlink can be treated separately.

Coordination Meetings

If no coordination is indicated then the new network can proceed directly to notification, otherwise detailed bilateral coordination must be undertaken with all affected administrations. Only when the agreement of all affected administrations has been obtained can the network proceed to notification. Status and protection is only finally achieved following successful notification and entry onto the MIFR.

The procedures adopted in coordination meetings are for bilateral agreement between administrations, normally based on ITU-R Recommendations but administrations may agree other procedures and techniques if they wish. Procedures (currently) only exist for GSO-GSO coordination. DeltaT/T is not normally used in coordination meetings and interference is usually analysed on the basis of carrier-to-interference ratio assessed against a protection ratio.

During coordination interference can be mitigated by:

  • Changing the shape of the coverage area of satellite beams or
  • improving sidelobe performance of the satellite antennas
  • Improving earth station sidelobe performance
  • Reducing satellite down-link power
  • Reducing earth-station up-link power
  • Frequency planning
  • Or even changing the orbital location of one of the satellites


Following the completion of all required coordinations the responsible administration can submit details of all coordinated assignments to the ITU. The ITU will undertake a number of regulatory and technical checks. If these are successful then the assignments will be entered into the MIFR and gain international recognition and protection. Procedures exist to deal with cases where agreements can’t be achieved.

Next: Section 7 - Conclusions


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