Analysis of Indoor Propagation and Wi-Fi 5.4 GHz Coverage Estimation using ITU-R P.1238 Model: A Case Study in Sealed Office Environments

Abstract

This study analyzes indoor radio wave propagation at 5.4 GHz and estimates Wi-Fi coverage using the ITU-R P.1238-13 model in a sealed commercial office environment designed for HVAC thermal efficiency in Makassar, Indonesia. The primary challenge is that airtight construction creates layered radio frequency barriers that degrade wireless coverage quality. RSSI measurements were collected at 110 grid locations within a 483 m² floor plan and compared with three propagation models: Free-Space Path Loss (FSPL), Log-Distance, and ITU-R P.1238-13. Empirical regression yielded a calibrated path loss exponent of n = 2.8 with a shadow-fading standard deviation of  = 2.0 dB, significantly higher than typical open offices ( = 2.0–2.4), confirming that sealed HVAC construction measurably limits propagation. Penetration loss measurements at 5.4 GHz characterized six building materials (4.2 dB for tempered glass up to 28.6 dB for double brick walls). The calibrated ITU-R P.1238-13 model achieved superior accuracy: MAE = 1.4 dB, RMSE = 1.7 dB, and Pearson r = 0.993. Coverage analysis identified a coverage hole (area without coverage) of 13.6% of the floor area (±66 m²) where RSSI dropped below -80 dBm. Secondary AP placement is projected to increase satisfactory coverage from 86.4% to ≥97%. This study validates ITU-R P.1238-13 as a reliable planning tool for 5.4 GHz Wi-Fi in sealed tropical offices.