Modeling Ka-band scintillation as a fractal process

We propose a model that describes the signal fading process due to scintill ation in the presence of rain, We analyzed a data set of uplink (30 GHz) an d downlink (20 GHz) attenuation values averaged over is intervals. The data are samples relative to ten significant events, for a total of 180 000 s r ecorded at the Spine d'Adda (North of Italy) station using the Olympus sate llite, Our analysis is based on the fact that the plot of attenuation versu s time recalls the behavior of a self-similar process. We then make various considerations, and propose a fractional Brownian motion model for the sci ntillation process. We describe the model in detail, with pictures showing the apparent self-similarity of the measured data. We then show that the Hu rst parameter of the process is a simple function of the rain fade. We desc ribe a method for producing random data that interpolate the measured sampl es, while preserving some of their interesting statistical properties, This method can be used for simulating fade countermeasure systems. As a possib le application of the model, we show how to optimize fade measurement times for fade countermeasure systems.