Empirical Path Loss Models for Long-Range Networks in Long Corridors of Multi-Floor Buildings

Long-range (LoRa) wireless networks in the UHF band are widely deployed in indoor sensing applications; however, standard propagation models such as ITU-R P.1238 and 3GPP do not accurately characterize LoRa performance because RSSI depends strongly on spreading factor (SF), bandwidth (BW), and signal-to-noise ratio (SNR), as well as building structures and inter-floor attenuation. This paper proposes new empirical path loss models for LoRa at 433 MHz, specifically developed for long-corridor, multi-floor buildings. The models incorporate a calibration factor for RSSI, an adaptive path loss exponent, and a floor attenuation factor (FAF) that increases by approximately 5 dB per floor. Measurements collected from four buildings demonstrate that the proposed models capture corridor wave-guiding behavior and extend the breakpoint distance to about 31.9 m. Validation results show high prediction accuracy, with RMSE values of 1.8–5 dB, outperforming ITU, LoRa, and 3GPP models. These models provide improved reliability for indoor LoRa network planning in complex multi-story environments.