Experimental analysis of propagation at 62 GHz in suburban mobile radio microcells

The results of line-of-sight (LOS) and nonline-of-sight (NLOS) mobile radio propagation experiments made to characterize 62-GHz suburban microcell channels employing omnidirectional receive antennas are presented. The mean signal power variation, cumulative distribution functions for the received signal envelopes, and corresponding power spectra are also given. Additional measurements were conducted to determine the power of the various reflected rays and their directions of arrival. A ray-tracing model considering reflections and diffractions is developed to represent LOS and NLOS suburban microcell propagation and assist in interpreting experimental results. Experimental results are compared with theoretical predictions obtained assuming smooth and rough building surfaces. LOS measurements have shown that the power in the received signal variation is primarily concentrated at low frequencies. High-frequency components, due to reflections from objects and surfaces opposite the base station, are present at a relatively low level. The value of the propagation exponent depends on the amplitude of reflections with respect to the direct path. The assumption of smooth reflecting surfaces overestimates the power associated with reflected components. However, the introduction of a surface roughness factor improves predictions. Reflections up to the second order are found to be adequate to represent microcell propagation. The contribution of diffraction to the signal envelope is negligible. NLOS results show a sharp drop in the mean signal level when the direct component is blocked. Coverage into the shadow region is limited to a few meters where single reflections keep arriving at the receive antenna.