Simulation and measurement of near-ground wave propagation for indoor scenarios

Abstract

Efficient and versatile wave propagation models for indoor and urban environments can find applications in many areas including wireless channel characterization, environmental sensing and radar applications such as fire and earthquake rescue missions. There are various indoor field prediction techniques available in the literature such as ray tracing, hybrid techniques and empirical models that are based on measurement results [1–2]. Models based on numerical solvers such as MoM, FEM and FDTD are usually not preferred due to high computational cost. Ray tracing techniques, being a high frequency approximation, are not valid for lower frequency (lower UHF and VHF) applications. In addition, existing ray-tracing routines, which are most commonly used for indoor field prediction, are inadequate for evaluating the signal coverage for near-ground networks since the scattered wave from the ground is only approximated by Geometrical Optics (GO) which neglects the more dominant higher order Norton surface waves. Therefore, for near-ground transceivers deployed in indoor and urban environments these higher order waves and their interactions with building walls and other indoor obstacles should be taken into account for accurate field calculations. A semi-analytic propagation model for indoor scenarios that fully takes into account the Norton waves by making use of the Dyadic Green's function for a half-space dielectric medium was recently proposed in [3]. A physical optics type approximation was utilized to handle scattered field from building walls which are the dominant scatterers in indoor settings. The derivation and validation of the technique using a numerical solution for the 2D case were presented. In this work, the method is extended to a more realistic indoor propagation scenarios where multipe scatterers exist. In the first section, the semi-analytic technique for 3D multi-wall scenarios is described followed by measurement results used to validate the new method for 3D single wall-building geometry. To further validate the accuracy of the proposed model, field coverage comparison between the semi-analytic method and a full-wave solver (Semcad X) for various cases is also presented.