Double-Directional 105 GHz Multipath Propagation Measurement in Lecture Hall Environment

This paper presents a comprehensive wideband indoor propagation characterization via real-world experiments at 105.8 GHz with a 4 GHz bandwidth in a lecture hall environment. Utilizing a double-directional channel sounding system with rotating horn antennas, we measure power angular delay profiles (PADPs) at multiple receiver (RX) positions. Our study derives a path loss model, delay characteristics, and angle characteristics, including path loss exponent, root mean square (RMS) delay spread (DS), K-factor, RMS azimuth angle spread of arrival (ASA), and RMS azimuth angle spread of departure (ASD). We compared these results with the 3GPP indoor hotspot (InH) office model (up to 100 GHz), highlighting both similarities and differences in propagation characteristics. Notably, the path loss exponent was found to be 1.49, which is lower than the 1.73 observed in the 3GPP InH-Office LoS model. Moreover, there were positive correlations between the above spread values and transmitter (TX)-RX distance, and negative correlations between K-factor and TX-RX distance, which were not considered in the 3GPP InH-Office LoS model. Furthermore, our analysis revealed a strong negative correlation in RMS ASA vs K-factor and RMS ASD vs K-factor, which are not accounted for in the current 3GPP InH office model. These findings emphasize the need to consider such correlations in accurate propagation models in lecture hall scenarios at the 105 GHz sub-terahertz band.