Bajrang Bansal

Time-Domain Solution for Transmitted Field Through Low-loss Dielectric Obstacles in a Microcellular and Indoor Scenario for UWB Signals

An analytical time-domain (TD) solution based on an established frequency-domain (FD) transmission model is presented for transmission of ultrawideband (UWB) signals through low-loss dielectric obstacles, in a microcellular and indoor propagation environment. This paper provides an in-depth analysis of the FD transmission model and presents a computationally more efficient direct TD transmission solution. Various obstacles considered in this paper include dielectric wedge and rectangular building with homogeneous, isotropic, and low-loss dielectric characteristics. Novel TD transmission coefficients, for transmission through an interface between air and a low-loss dielectric medium, are proposed for both hard and soft polarizations. The proposed TD solution is validated against the numerical inverse fast Fourier transform of the exact FD (IFFT-FD) solution and the results are found to be in very good agreement with each other. The computational efficiency achieved through the proposed TD solution is demonstrated by comparing its computation time with that of the exact IFFT-FD solution.

A New Time-Domain Solution to Transmission Through a Multilayer Low-Loss Dielectric Wall Structure for UWB Signals

In this work the time-domain solution for transmission through a multilayer wall structure has been presented. A time-domain transmission coefficient formulation for transmission through an interface between two low-loss dielectric mediums with different electrical properties is derived. Both hard and soft polarizations are considered. A novel ray tracing algorithm for multilayer wall structure has been presented with accuracy of ray-traced path as close as order of

Time-Domain Solution for Corner Diffraction of UWB Signals by Flat Plate Structures with the Higher Order Diffraction Included

10^{-5}

A Novel Time-Domain Formulation of 3-D Dyadic Diffraction Coefficient for Arbitrary Polarized UWB Signals with Oblique Incidence

10-5. Further, in depth formulation for actual refracted angles for different layers of the wall has been presented and exact frequency-domain formulation for transmitted field at the receiver has been obtained. The exact formulation has been simplified under the condition of low loss assumption and this simplified formulation has been converted to time-domain formulation using inverse Laplace transform. The proposed time-domain solution has been validated with the inverse fast Fourier transform of the corresponding exact frequency-domain solution. Further the computational efficiency of both the methods has been compared.

Time-Domain Solution of Transmission through Multi-modeled Obstacles for UWB Signals

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.

Frequency-domain analysis of multiple diffractions of spherical waves by a rectangular building in wireless channel

ABSTRACT In this paper, a new time-domain (TD) solution is proposed for corner diffraction by finite-edge flat plate structures. First, TD solution is considered for corner amplitude diffraction by edges of a flat plate, and then for corner slope diffraction (CSD) which takes into account the finiteness of the plate edges. To show the significance of CSD, results have been shown for diffraction of ultra-wideband signals by edges of a horn antenna which is a structure made by interconnected flat plates. The comparison between the TD solution and the numerical inverse fast Fourier transform of the corresponding frequency-domain solution validates the proposed solution. Finally, the computation times of both methods have been compared.

A new time-domain corner diffraction coefficient for metallic and dielectric objects for UWB signals

In this paper, a new time-domain (TD) diffraction coefficient for non-perfectly conducting wedges is proposed that is applicable to the case when the source illuminates either one or both sides of wedge for different wedge angles. The TD received field is compared with the inverse fast Fourier transform (IFFT) of frequency-domain (FD) solution. Finally considering hard polarization, the computational efficiency of both methods (TD and IFFT-FD) has been compared.

Time-domain analysis of monocycle pulse propagation for 5G UWB communications

In this paper, a new time-domain (TD) three-dimensional dyadic diffraction coefficient is proposed for ultra wideband (UWB) signals with arbitrary polarization and oblique incidence. Simulation results are presented for diffraction by a single wedge, double wedge and building scenario with consecutive diffractions. An excellent agreement of the proposed TD solution with the inverse fast Fourier transform (IFFT) of the corresponding exact frequency-domain (FD) solution proves the validity of the TD solution. Also it is observed that the TD solution is computationally more efficient than the IFFT–FD method. The presented TD solution can be used to analyze diffracted field for arbitrary polarized UWB signals with oblique incidence.