Measurement-based investigations of radio wave propagation: An expose on building corner diffraction

Predicting performance metrics for the next-generation of multi-mode and multi-antenna wireless communication systems demands site-specific knowledge of the wireless channels underlying radio wave propagation mechanisms. This thesis describes the first measurement system capable of characterizing individual propagation mechanisms in situ. The measurement system merges a high-resolution spatio-temporal wireless channel sounder with a new field reconstruction technique to provide complete knowledge of the wireless channels impulse response throughout a 2-dimensional region. This wealth of data may be combined with space-time filtering techniques to isolate and characterize individual propagation mechanisms. The utility of the spatio-temporal measurement system is demonstrated through a measurement-based investigation of diffraction around building corners. These measurements are combined with space-time filtering techniques and a new linear wedge diffraction model to extract the first semi-empirical diffraction coefficient. Specific contributions of this thesis are: (1) The first ultra-wideband single-input multiple-output (SIMO) channel sounder based upon the sliding correlator architecture. (2) A quasi 2-dimensional field reconstruction technique based upon a conjoint cylindrical wave expansion of coherent perimeter measurements. (3) A wireless channel "filming" technique that records the time-domain evolution of the wireless channel throughout a 2-dimensional region. (4) High-resolution measurements of the space-time wireless channel near a right-angled brick building corner. (5) The application of space-time filtering techniques to isolate the edge diffraction problem from the overall wireless channel. (6) An approximate uniform geometrical theory of diffraction (UTD)-style linear model describing diffraction by an impedance wedge. (7) The first-ever semi-empirical diffraction coefficient extracted from in situ measurement data.;This thesis paves the way for several new avenues of research. The comprehensive measurement data provided by channel "filming" will enable researchers to develop and implement powerful space-time filtering techniques that facilitate measurement-based investigations of radio wave propagation. The measurement procedure described in this thesis may be adapted to extract realistic reflection and rough-surface scattering coefficients. Finally, exhaustive measurements of individual propagation mechanisms will enable the first semi-empirical propagation model that integrates empirical descriptions of propagation mechanisms into a UTD-style mechanistic framework.