title: ITU model for indoor attenuation
text: # 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:
  
  $L\;=\;20\;\log _{10}f\;+\;N\;\log _{10}d\;+\;P_{f}(n)\;-\;28$
  
  where,
  
      L = the total path loss. Unit: decibel (dB).
      f = Frequency of transmission. Unit: megahertz(MHz).
      d = Distance. Unit: meter (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 |
  | 1.2–1.3 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 |
  