A New Time-Domain Model for Multiple Scattering of UWB Signals Through Lossy Obstacles

Abstract

In this paper, a new time-domain (TD) model is proposed for multiple scattering of ultra wideband (UWB) signals through lossy obstacles. Propagation through structures like wedge, single building, and double buildings is presented where buildings are supposed to have rectangular cross sections. Considering two-dimesnional (2-D) and realistic three-dimensional (3-D) scenarios, first an accurate path-tracing algorithm is proposed for multiple scattering of UWB signals through different 2-D and 3-D scenarios and then, TD solution is presented for realistic multiple scattering problems where a single ray-path can undergo diffraction, transmission, and reflection successively. Results are shown for both soft and hard polarizations. Considering Gaussian doublet pulse, the accuracy of the presented TD solution is confirmed by comparing the TD results with the numerical inverse fast Fourier transform (IFFT) of the corresponding frequency-domain (FD) results. It has been found that the field strength at the receiver (Rx) undergoes significant attenuation and distortion for different multiple scattering scenarios. For an in-depth analysis of pulse distortion at Rx, the UWB channel impulse response is analyzed for multiple scattering scenario. Power profile for multiple scattering scenario is also observed to signify the received power at the Rx. To characterize the multipath propagation, UWB multipath is analyzed in terms of time dispersion parameters like mean excess delay and root mean square delay spread. Further to confirm the generality of the proposed TD solution, the results are shown for a variety of other UWB pulses like monocycle and fourth-order Gaussian monocycle pulses. Finally, the computational efficiency of the TD and IFFT-FD methods is compared.