Introduction

In 2007, the World Radiocommunication Conference (WRC-07) adopted a revised FSS Plan (contained in Appendix 30B to the Radio Regulations), in which a number of technical parameters and criteria were modified. The above-mentioned Plan provides all ITU Members with protected orbital-frequency resources. In the FSS Plan, the criterion for the carrier-to-noise ratio (C/N) is defined under rain-faded conditions but the criterion for the carrier-to-interference (C/I) is defined in clear-sky conditions. In some cases, as a consequence of approved technical criteria and unavoidable signal attenuation due to rain, the energy balance of planned allotments in the 13/10-11 GHz frequency bands may become substantially worse.

All mathematical computations made in this Report are based on the assumption that the uplink power is designed to strictly achieve a C/N ratio of 21 dB under rain-faded conditions. It should be noted that test points of some allotments have higher faded C/N values in the uplink (i.e. greater than 21 dB).

Annex 1 to this Report provides supplementary information which examines two additional impacts of rain attenuation on system margin which are not taken into account by the FSS Plan. Annex 2 contains all the terms and their respective definitions used in the Report and in Annex 1.