Werner Wiesbeck

Verification of a Hybrid Ray-Tracing/FDTD Model for Indoor Ultra-Wideband Channels

For development and optimization of ultra-wideband (UWB) based localization and imaging algorithms deterministic channel models are needed, which provide realistic channel impulse responses for given indoor scenarios. As the considered frequency band is 3.1 to 10.6 GHz the dimensions of objects in most indoor scenarios are small compared to the wavelength at lower frequencies. To simulate wave propagation properties in such scenarios an existing ray-tracing model has been combined with the finite difference time domain method (FDTD). The scattering properties of small objects are computed using FDTD and incorporated in a ray-tracing simulation as single scattering points. The simulation results are compared to measurements in a complex laboratory scenario. This comparison shows that the combined ray-tracing/FDTD model provides in complex indoor scenarios higher precision for propagation paths with small delay time. However the overall improvement of the simulation quality is limited and in comparison to the potential improvement by considering the diffuse scattering in the ray-tracing simulation almost negligible.

Simulation and Measurement Based Correlation Estimation for Ultra Wideband Antenna Arrays

In order to optimize the performance of diversity antenna systems for communications applications it is desirable to have little correlation between the signals at the different receiving antennas. This paper deals with the estimation of the correlation coefficients of a linear ultra wideband antenna array in an indoor propagation scenario. A suitable approach for the estimation procedure is described and applied to propagation simulation results as well as to measurement results. Correlation coefficients obtained from the proposed estimation procedure are compared to analytically calculated correlation coefficients in order to verify the estimation procedure.