The ITU

Itu

Itu is an old and historic municipality in the state of São Paulo in Brazil. The population in 2009 was 157,384 and the area is 641.68 km². The elevation is 583 m. This place name comes from the Tupi language, meaning big waterfall. Itu is linked with the highway numbered the SP-75 and are flowed...

 Indoor Propagation Model, also known as ITU Model for Indoor Attenuation, is a radio propagation model

Radio propagation model

A radio propagation model, also known as the Radio Wave Propagation Model or the Radio Frequency Propagation Model, is an empirical mathematical formulation for the characterization of radio wave propagation as a function of frequency, distance and other conditions...

 that estimates the path loss

Path loss

Path loss is the reduction in power density of an electromagnetic wave as it propagates through space. Path loss is a major component in the analysis and design of the link budget of a telecommunication system....

 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

Path loss

Path loss is the reduction in power density of an electromagnetic wave as it propagates through space. Path loss is a major component in the analysis and design of the link budget of a telecommunication system....

 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.

The model

The ITU indoor path loss model is formally expressed as:



where,

L = the total path loss

Path loss

Path loss is the reduction in power density of an electromagnetic wave as it propagates through space. Path loss is a major component in the analysis and design of the link budget of a telecommunication system....

. Unit: decibel

Decibel

The decibel is a logarithmic unit that indicates the ratio of a physical quantity relative to a specified or implied reference level. A ratio in decibels is ten times the logarithm to base 10 of the ratio of two power quantities...

 (dB).

f = Frequency

Frequency

Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...

 of transmission. Unit: megahertz(MHz).

d = Distance. Unit: metre (m).

N = The distance power loss coefficient.

n = Number of floors between the transmitter and receiver.

P_f(n) = the floor loss penetration factor.

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.

Frequency Band	Residential Area	Office Area	Commercial Area
900 MHz	N/A	33	20
1.2 GHz	N/A	32	22
1.3 GHz	N/A	32	22
1.8 GHz	28	30	22
4 GHz	N/A	28	22
5.2 GHz	N/A	31	N/A

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 GHz	n	4n	15+4(n-1)	6 + 3(n-1)
2.0 GHz	n	4n	15+4(n-1)	6 + 3(n-1)
5.2 GHz	1	N/A	16	N/A

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.