A New Universal Approach to Time-Domain Modeling and Simulation of UWB Channel Containing Convex Obstacles Using Vector Fitting Algorithm

The paper presents a new approach to time-domain modeling of ultra-wideband (UWB) channels with multiple convex obstacles. Rational approximation exploiting the vector fitting algorithm (VF) is used for deriving the closed-form impulse response of a multiple diffraction ray creeping on a cascade of convex obstacles. The VF algorithm is performed with respect to new generalized variables proportional to frequency but also taking into account geometrical parameters of the obstacles. The limits of the approximation domain for the VF algorithm reflect the range of UWB channel parameters that can be met in practical UWB channel scenarios. The results of VF approximation have the form of a finite series of partial fractions in the frequency domain, which then is easily transformed to the time domain. Obtained in this way, impulse response is a sum of exponential functions. As a consequence, in simulations of electromagnetic (EM) wave propagation, we can implement very fast and effective convolution algorithms with any input signal or perform simulations implementing SPICE-like programs.