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 cha nnels employing omnidirectional receive antennas are presented. The mean si gnal power variation, cumulative distribution functions for the received si gnal envelopes, and corresponding power spectra are also given. Additional measurements were conducted to determine the power of the variou s reflected rays and their directions of arrival, A ray-tracing model consi dering reflections and diffractions is developed to represent LOS and NLOS suburban microcell propagation and assist in interpreting experimental resu lts. Experimental results are compared with theoretical predictions obtaine d 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, d ue to reflections from objects and surfaces opposite the base station, are present at a relatively low level, The value of the propagation exponent de pends on the amplitude of reflections with respect to the direct path. The assumption of smooth reflecting surfaces overestimates the power associated with reflected components. Hoc-ever, the introduction of a surface roughne ss factor improves predictions. Reflections up to the second order are foun d to be adequate to represent microcell propagation. The contribution of di ffraction to the signal envelope is neglibible. NLOS results show a sharp d rop 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.