Improving the accuracy of ray-tracing techniques for indoor propagation modeling

Problems with the use of ray-tracing techniques in indoor propagation envir onments are identified, and a new set of widely applicable diffraction coef ficients is developed. The limitations on the accuracy of the ray-tracing m ethod in indoor propagation environments are first assessed. The effects of scatterers with dimensions approaching the wavelength of operation and of scatterers with finite conductivity are considered, The accuracy of ray tra cing is quantified by comparison to a full-wave simulation technique, which combines the finite-difference time-domain method with a spatial transform ation technique, the Kirchhoff surface integral formulation. Simulation res ults demonstrate that when the magnitude and phase of the received signal c omponents are properly accounted for, the ray-tracing solution mag be accur ate down to a fraction of a wavelength. A new set of diffraction coefficien ts is presented for calculations involving obstacles with finite conductivi ty. The new coefficients eliminate an artificial dip in the diffracted fiel d strength, which is often encountered when currently available techniques are used. Validation is provided by comparison with full-wave simulations a nd measurements, improved accuracy in both the illuminated and shadowed reg ions is demonstrated.