Empirical Path Loss Model and Small-Scale Fading Statistics in an Indoor Office Environment in 6 and 37 GHz Shared Bands

The low-cost unlicensed (e.g., 5.925 -7.125 GHz) and shared spectra (e.g., 37 - 37.6 GHz and 42 - 42.5 GHz) are of interest for operators to deploy hotspot 5G/6G base stations (BSs) or Wi-Fi access points (APs) for Fixed Wireless Access (FWA) and mobile services. The wireless propagation channel determines the coverage, capacity, radio link design, and network planning. CableLabs conducted a measurement campaign for the indoor-office scenario to study the related propagation channel characteristics. In this paper, the data, the path loss models, and small-scale fading statistics are presented. The channel sounding system uses 500 MHz bandwidth, centered at 6.175 and 37.3 GHz. The receiver was mounted near the ceiling (e.g., BS or AP) and the transmitter was 1.1 m above ground (e.g., cellphone or laptop). Omnidirectional antennas with a large vertical beamwidth are deployed on both the transmitter and receiver. The receiver antenna consists of a virtual circular array (VCA) that acquires 1000 channel impulse responses (CIRs) in one rotation. The angle of arrival (AoA) and Rician K-factor are extracted by comparing the CIRs. 76 test positions were measured with distances from 3 to 85 m in line-of-sight (LOS), obstructed-LOS (OLOS), non-LOS (NLOS), and deep NLOS conditions. The experimental path loss models, K-factor, root-mean-square (RMS) delay spread (RMS-DS), and RMS angular spread (RMS-AS) are reported and compared with the 3GPP TR 38.901 models.