On the Influence of DSD Fluctuations on the Cumulative Distributions of Rain Attenuation at Millimeter Waves

Rain attenuation at millimeter waves is progressively more influenced by the Drop Size Distributions (DSD). This influence has been characterized in the last years with databases of DSD gathered in Madrid, Spain and other sites. The results showed that a significant variability of rain specific attenuation <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\gamma(\text{dB}/\text{km})$</tex> can be expected from DSD fluctuations. A model for the probability distribution function (pdf) of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\gamma$</tex> was proposed. From this model, the question was raised whether the cumulative distributions of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\gamma$</tex> would be affected by this variability. This paper tries to answer to this question, by comparing the complementary cumulative distribution functions (CCDF) obtained with and without considering this variability. The conclusion is that the variability has a significant effect on the CCDFs, more relevant as frequency grows and for lower time percentages. The application of these results to system planning would lead to higher link margins.