The ITU indoor propagation model, also known as ITU model for indoor attenuation, formally standardized in ITU-R Recommendation P.1238, is an empirical radio propagation model that estimates the path loss inside a room or a closed area inside a building delimited by walls of any form. Suitable for appliances designed for indoor use, this model approximates the total path loss an indoor link may experience.

Applicable to/under conditions

Primarily applied in network dimensioning for Wi-Fi, indoor cell systems (picocells and femtocells), DECT, and IoT sensor networks, the model predicts the median transmission loss between a transmitter and receiver located within the same building. It accounts for distance, operating frequency, building environment (residential, office, or commercial), and penetration through intermediate floors.

Coverage

Frequency: 900 MHz to 5.2 GHz

Floors: 1 to 3

Mathematical formulations The model

The ITU-R indoor path loss model is a modified log-distance path loss model. The site-general median path loss L is expressed as:

where, L = total transmission path loss between transmitter and receiver (dB). f = Transmission Frequency in megahertz (MHz). d = Straight-line 3D distance between transmitter and receiver in metres. N = The distance power loss coefficient (dimensionless). n = Number of floors between the transmitter and receiver. Pf(n) = the floor loss penetration factor (dB).

Calculation of distance power loss coefficient

The distance power loss coefficient, N is the quantity that expresses the loss of signal power with distance. This coefficient is an empirical one. Some values are provided in Table 1.Propagation data and prediction methods for the planning of indoor radio communication systems and the radio local area networks in the frequency range 900 MHz to 100 GHz, ITU-R Recommendations, Geneva, 2001

Frequency band Residential area Office area Commercial area 900 MHz N/A 33 20 1.2–1.3 GHz N/A 32 22 1.8–2.0 GHz 28 30 22 4 GHz N/A 28 22 5.2 GHz 30 (apartment), 28 (house) 31 N/A 5.8 GHz N/A 24 N/A 6.0 GHz N/A 22 17

Calculation of floor penetration loss factor

The floor penetration loss factor is an empirical constant dependent on the number of floors the waves need to penetrate. Some values are tabulated in Table 2.

Frequency band Number of floors Residential area Office area Commercial area 900 MHz 1 N/A 9 N/A 900 MHz 2 N/A 19 N/A 900 MHz 3 N/A 24 N/A 1.8–2.0 GHz n 4n 15+4(n-1) 6 + 3(n-1) 5.2 GHz 1 N/A 16 N/A 5.8 GHz 1 N/A 22 (1 floor), 28 (2 floors) N/A

See also

Log-distance path loss model Free-space path loss Radio propagation model Young model

References

Further reading

Introduction to RF propagation, John S. Seybold, 2000, John Wiley and Sons. Propagation data and prediction methods for the planning of indoor radio communication systems and the radio local area networks in the frequency range 900 MHz to 100 GHz, ITU-R Recommendations, Geneva, 2001. Propagation data and prediction methods for the planning of indoor radiocommunication systems and radio local area networks in the requency range 900 MHz to 100 GHz, Recommendation ITU-R P.1238-7, Geneva, 2012