ITU model for indoor attenuation

The ITU indoor propagation model, also known as "ITU model for indoor attenuation", is a 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.
This model is applicable to only the indoor environments. Typically, such appliances use the lower microwave bands around 2.4 GHz. However, the model applies to a much wider range.
Coverage.
Frequency: 900 MHz to 5.2 GHz
Floors: 1 to 3
Mathematical formulations.
The model.
The ITU indoor path loss model is formally expressed as:
formula_1
where,
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.
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.