Path Loss and Directional Gain Measurements at 28 GHz for non-Line-of-Sight Coverage of Indoors with Corridors

TL;DR

This study provides extensive 28 GHz indoor measurements in corridors and rooms, revealing lower azimuth spread and higher penetration loss than standards, with models predicting path gain and implications for access point placement.

Contribution

It offers detailed measurement data and modeling of 28 GHz indoor propagation, highlighting corridor guiding effects and providing practical deployment insights.

Findings

Lower RMS azimuth spread in corridors (7°) compared to standards (42°).

Higher penetration loss into rooms and around corners (30-32 dB).

Path gain modeled with 3.9 dB RMS error using mode-diffusion model.

Abstract

Adequate coverage with high gain antennas is key to realizing the full promise of the bandwidth available at mm/cm wave bands. We report extensive indoor measurements at 28 GHz (1000 links, 9.9 million individual power measurements, 10 offices, 2 buildings), with/without line-of-sight (LOS) using a continuous wave channel sounder, with a 10o spinning horn, capable of capturing a full azimuth scan every 200 ms, in up to 171 dB path loss to characterize coverage with 90% confidence level. The environment had prominent corridors and rooms, as opposed to open/mixed offices in latest 3GPP standards. Guiding in corridors leads to much lower RMS azimuth spread (7 degree median in corridor non-LOS vs. 42 degree in 3GPP) and higher penetration loss into rooms and around corners (30-32 dB, some 12 dB more loss than 3GPP at 20 m non-LOS). Measured path gain in non-LOS is predicted by a mode-diffusion model with 3.9 dB RMS error. Scattering degraded azimuth gain by up to 4 dB in the corridor and 7 dB in rooms with 90% probability. Link simulations in a canonical building indicate every corridor needs an access point to provide 1 Gbps rate to adjoining rooms within 50 m using 400 MHz of bandwidth.