In situ measurement of reflection and diffraction coefficients of UHF radio waves on buildings using a ring array

摘要

The lack of reliable estimates of the reflection and diffraction coefficients of radio waves by urban structures is one of the main barriers to deterministic modeling of the UHF channel. In complex environments such as urban areas, the reception of multiple echoes of the transmitted signal generally prevents direct in situ measurements of these coefficients. For the present study, the contributions of the different paths to the measured received power were separated by coupling the channel impulse response sounding with the determination of the direction of arrival (DOA). From experimental data we were able to isolate the field component generated by reflection or diffraction on buildings by both delay and angle of incidence. We deduced the corresponding reflection and diffraction coefficients. The wave DOA was determined using a ring array. The angle of arrival patterns were extracted by two different methods, namely the Wiener inversion method and the beam-forming method. The coefficients deduced by these two techniques are shown to be very close. These results are also similar to those obtained without the help of DOA separation when delay resolution makes them available. We also show the validity of geometrical rays to represent reflection and diffraction of decimetric waves on the kind of building concerned.