RES901 – 432 – MOD RESOLUTION 901 (REV.WRC-15) Determination of the orbital arc separation for which coordination would be required between two satellite networks operating in a space service not subject to a Plan The World Radiocommunication Conference (Geneva,2015), considering a) that WRC-2000 adopted a coordination arc concept in Appendix 5 to simplify the coordination between fixed-satellite service (FSS) networks in certain frequency bands between 3.4 GHz and 30 GHz; b) that in frequency bands below 3.4 GHz, mobile-satellite service (MSS) satellite networks normally have to coordinate with other networks with overlapping service areas operating anywhere in the visible arc; c) that the application of such a concept was limited to the frequency ranges where very large numbers of FSS satellite filings had been received by ITU-R; d) that many satellite networks and systems are now proposing to use higher frequency bands for which the coordination arc does not yet apply; e) that the Radio Regulations Board (RRB) adopted a Rule of Procedure on No. 9.36 that extended the coordination arc concept to the FSS and broadcasting-satellite service (BSS), not subject to a Plan, and in all frequency bands above 3.4 GHz until a review by WRC-03; f) that the use of the coordination arc considerably reduces the volume of data that needs to be supplied to the Radiocommunication Bureau under Section D of Annex 2 to Appendix 4; g) that application of the coordination arc concept has the potential to reduce the workload of the Bureau in identifying affected administrations; h) that the coordination arc concept may be valid for all geostationary space stations operating in any space radiocommunication service above 3.4 GHz that is not subject to a Plan, but may require different values for different services and frequency bands; i) that the ITU-R studies for other services and for frequency bands above 17.3 GHz, except for the 17.7-20.2 GHz and 29.5-30 GHz ranges for the FSS, have not been completed; j) that application of the coordination arc concept could facilitate the introduction of satellite services above 17.3 GHz after the studies conclude on the appropriate value(s) of the coordination arc,