Fractal generation of rain fields: synthetic realisation for radio communications systems

Abstract

The spatio-temporal variation of rain fields is a key input into the development of radio systems which operate at frequencies above 10 GHz in a spectrally efficient fashion. Fractal methods have been proven helpful in the analysis and synthesis of rain fields. A fractal model is presented for the simulation of meteorologically representative rain fields, using an additive iterative process in the logarithmic domain. The resulting simulated rain fields are monofractal fields that have appropriate spectral density exponent, fractal dimension and behaviour that is consistent with radar analyses of convective or stratiform types of events. Justification to use a monofractal method of simulation is presented through the analysis of the moment scaling function for fields of rain rate and log rain rate values recorded by the Chilbolton Advanced Meteorological Radar, based in the south of England. The results of the analysis indicate that log rain fields can be analysed and simulated by using monofractal techniques with sufficient accuracy for the purposes of synthesising rain fields for communication systems design and operation. Cumulative distributions of rain rate exceedance derived from the simulated fields are compared with the measured rain gauge data and curves calculated from the ITU-R rain models, with promising results.