Indoor Channel Propagation Measurements and Statistical Modeling for FR3 Mid-Band Spectrum at 12–18 GHz

New spectrum allocations in the FR3 band that ranges between 7–24 GHz, are being considered for future 5G and 6G cellular deployments. This paper presents indoor Line-of-Sight (LoS) path loss measurements and angular scattering measurements using directional horn antennas for the FR3 mid-band spectrum between 12–18 GHz. The measurements were carried out for both co-polarized configurations while an example of a cross-polarized measurement at LoS is shown, that verifies depolarization of the waves with Cross Polarization Discrimination (XPD) values across all distances being above 30 dB. The LoS path loss statistics confirm the Friis transmission model, showing path loss exponents that are close to those of free space, while delay spreads are shown to decrease over distance. The angular statistics derived from empirical measurements of indoor surfaces show that significant multipath components can be detected over a wide range of reflection angles. This is particularly true for plastered surfaces, which have a complex internal structure commonly found in modern buildings. Discontinuities of varying scales on these surfaces create scattered components within this range, similar to those observed at 100 GHz. This suggests that further work is needed for the characterization of different building structures with internal features comparable in size to the wavelength. Such features may contribute to frequency-selective scattering, which is important for accurately modeling future cellular communications within this band.