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Rain attenuation is .the dominant propagation impairment for high-frequency microwave systems. System design therefore requires the knowledge of the one-minute integrated-rain-rate cumulative distribution function over the coverage area in order to determine the appropriate transmitter and receiver characteristics. This paper presents a set of rain-rate contour maps, useful for link and network power sizing in Nigeria. They were developed using a combination of first-order rain-rate statistical methods: the Moupfouma-Martin model for rain-rate prediction in tropical regions, and the Rice-Holmberg model.

The conversion of rain-rate cumulative distributions from any integration time, T, to one minute is a viable option whenever local one-minute data (time series or cumulative distribution functions) are not available for microwave system design. This\ud paper reviews some of the most common rain-rate cumulative-distribution conversion methods. For selected models, it provides a complementary set of coefficients for regional and global application by performing regression to a measurements\ud database. The performance of each model is analyzed, together with its adaptability to various climatic regions. Finally, recommendations with regard to the global applicability of models are given

When 1-minute integrated rainfall rate statistics are not available for microwave system design, the conversion from rain rate cumulative distributions with a longer integration time T can be envisaged. A new set of global coefficients for the current ITU-R method of rain statistics conversion is proposed and tested against a comprehensive database.\ud Results are compared with those provided by the currently recommended ITU-R method. Moreover, the method’s applicability is extended to include 60-minute integration time conversions. Tests show that the new set of coefficients performs better than the ITU-R one over its applicability range

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