| The
Standard Computation Programme for Determining the Need for Coordination of NGSO MSS systems (space to earth) with the Fixed Service. In 1996, a Group of Experts within CEPT had been created with the aim of developing a Standard Computation Program (SCP) to determine whether an NGSO MSS system would need to coordinate with existing Fixed Service systems. The Standard Computation Programme for Determining the Need for Coordination of NGSO MSS systems (space to earth) with the Fixed Service. The Group of Experts produced an information document for the February 96 meeting of Working Party 8D, which was copied in a liaison statement to WP 9D (meeting at the same time). It was clear that both groups had interests in the development of the SCP and on May 1st 1996 a Joint Rapporteurs Group (JRG 8D/9D) was set up to develop, among other things, the SCP methodology. The need to develop an SCP was a consequence of the filings of many NGSO MSS systems in the 1-3GHz bands. Detailed coordination between each MSS systems and all potentially affect FS systems would be an enormous task, and some pre-coordination filter was needed. In anticipation that some simulation would be needed, MSS organisations had been producing simulation software for some time. By this time Visualyse was also well enough developed to be useful for coordination and a candidate implementation of the SCP. In fact Visualyse was already the industries leading interference analysis product, and was able to model accurately the MSS systems under consideration. The development of Visualyse and the efforts of some MSS operators in developing their own software meant there was enough experience available to allow the JRG to move ahead quickly with itís work. Transfinite Systems staff had been involved in the development of methodologies for this kind of simulation since 1992 and were key members of the JRG software experts group. Other than SCP, the JRG also addressed detailed coordination issues and in October 1997 ITU-R Recommendation M.1319 was approved. Visualyse was specified in the JRG Chairmanís report as an acceptable implementation of Rec M.1319 in the context of Resolution 716. The task of defining the SCP methodology proved to be quite difficult. The point about the SCP is that it defines a "coordination trigger". If an NGSO MSS system does not pass the tests set in the SCP then further detailed coordination under Rec M.1319 is needed. The two competing parties in the JRG wanted different emphasis in the SCP, for obvious reasons, i.e. the FS operator wants to be certain that the worst case assumptions are used so that no systems which could cause interference can pass the SCP tests. On the other hand the MSS operator does not want to trigger every possible case, and thereby increase the coordination effort needed many times. The Recommendation that captures the SCP methodology (ITU-R Rec M.1143) was also approved in October 1997. Visualyse was adapted to take account of this Recommendation and subsequently submitted to the ITU-R for accreditation, in response to an ITU circular letter (CR70), requesting software from all administrations. The validation and verification process continued in JRG 8D/9D. Visualyse was run for several test cases and the results compared to results from other programs. Results obtained were in close agreement, leading the chairman to conclude: - Simulation results from independent SCP computer programmes [Visualyse, ICO SCP] provide very closely aligned results; and - the description of the methodology described in Rec ITU-R M.1143-1 is sufficient at this stage and that no further revisions are required ; So the methodology
has been defined and, Visualyse has been shown to be compliant and in agreement with other
simulations. The validation process continues, all results are referenced to Visualyse.
Visualyse is the only commercially available package that has been tested against Recs
M.1143 and M.1319 in this way. |