An efficient method for simulation of frequency selective isotropic Rayleigh fading

This paper addresses the task of efficiently simulating several independent random processes, each with the nonrational power spectral density resulting from isotropic Rayleigh fading. There are two primary classes of simulation techniques, those based on Jakes' (1974) method of superimposing tones and those based on rational approximation of the Doppler spectrum. The technique described in this paper is based on rational approximation, so that it is simple to approximate WSSUS frequency selective channels (i.e., simple to generate several independent fading processes). The technique is based on the approach suggested by Castoldi, et al. (see Proceedings of 4th IEEE Personal and Indoor Mobile Radio Communication Conference, 1994), which provides efficient simulation of processes with low normalized Doppler rates. This paper contains a modified rational approximation design based on this multirate approach. The output statistics of the cyclostationary fading process are derived and the effects of various design choices are characterized. Also, a method of rapid initialization of the simulator is provided for efficient simulation of packetized radio networks. Software routines are available from the authors in electronic form for general non-profit use.