Theoretical and Experimental Study of Indoor Propagation in the FR3 Band for LoS and NLoS Scenarios

Abstract This study examines the propagation characteristics of the new FR3 frequency band (Upper mid‐band) in indoor environments under both line‐of‐sight (LoS) and non‐line of sight (NLoS) conditions, using theoretical analysis and experimental measurements. For comparison, the measured radio channels are reconstructed using advanced ray‐tracing techniques with fine‐tuning of all propagation mechanisms. The proposed Path Loss (PL) Floating‐Intercept (FI) models show an error variance of 0.53 dB for measured PL and 5.5 dB for simulated PL in the LoS scenario. A convergence analysis for the LoS case reveals that simulating more than four reflections is unnecessary to minimize the error in Relative Received Power (RRP) between measurements and simulations. Additionally, the mean RMS delay spread (RMS DS) values observed were 3.86 ns from measurements and 4.17 ns from ray‐tracing simulations. In the NLoS scenario, the proposed PL FI model exhibits an error variance of 6.9 dB for the measured PL and 28.5 dB for the simulated PL. Meanwhile, the mean RMS DS values were 15.18 ns from measurements and 11.86 ns from simulations. Additionally, the results indicate a decreasing trend in RMS DS values with increasing frequency across the FR3 band in NLoS conditions. The simulations also reveal channel sparsity under NLoS conditions, indicating a reduction in the number of significant multipath components. This is primarily caused by severe attenuation and the dominance of only a few strong paths, as demonstrated by the results of the proposed model.