Indoor 90 GHz Channel Measurement Results for LOS to NLOS Transitions

Millimeter wave (mmWave) communication systems can offer unprecedented data rates, but typically employ directional antennas to ensure adequate link range, and in non-line-of-sight (NLOS) regions, must often “search” in the angular domain for a signal of significant strength. In this paper we quantify some channel characteristics for indoor settings in the 90 GHz band, focusing on LOS-to-NLOS transitions. Our results are empirical, based upon measurements using a 500-MHz bandwidth signal. These channel transitions can present some of the most challenging conditions to link reliability. We quantify the range and rate of change of angle of arrival of the strongest multipath component, root mean-square delay spread, and stationarity distance. For these transitions, path loss changes of 13 dB and strongest-component angle of arrival changes up to 100 degrees were found over distances of a few cm.