Simulation of rain fade on arbitrary microwave link networks by the downscaling and interpolation of rain radar data

To predict the Quality of Service at a node in heterogeneous networks of line-of-sight, terrestrial, microwave links requires knowledge of the spatial and temporal statistics of rain over scales of a few meters to tens or hundreds of kilometers, and over temporal periods as short as 1 s. Meteorological radar databases provide rain rate maps over areas with a spatial resolution as fine as a few hundred meters and a sampling period of 2 to 15 min. Such two-dimensional, rain rate map time series would have wide application in the simulation of rain scatter and attenuation of arbitrary millimeter-wave radio networks, if the sampling period were considerably shorter, i.e., of the order of 10 s or less, and the integration volumes smaller. This paper investigates a stochastic-numerical method to interpolate and downscale rain rate field time series to shorter sampling periods and smaller spatial integration areas, while conserving the measured and expected statistics. A series of radar derived rain maps, with a 10 min sample period, are interpolated to 10 s. The statistics of the interpolated-downscaled data are compared to fine-scale rain data, i.e., 10 s rain gauge data and radar data with a 300-m resolution. The interpolated rain map time series is used to predict the fade duration statistics of a microwave link, and these are compared to a published and ITU-R model.