Log-distance path loss model

The log-distance path loss model is a radio propagation model that predicts the path loss a encounters inside a building or densely populated areas over distance.
Mathematical formulation.
The model.
Log-distance path loss model is formally expressed as:
where
Corresponding non-logarithmic model.
This corresponds to the following non-logarithmic gain model:
where
formula_16 is the average multiplicative gain at the reference distance formula_8 from the transmitter. This gain depends on factors such as carrier frequency, antenna heights and antenna gain, for example due to directional antennas; and
formula_14 is a stochastic process that reflects flat fading. In case of only slow fading (shadowing), it may have log-normal distribution with parameter formula_13 dB. In case of only fast fading due to multipath propagation, its amplitude may have Rayleigh distribution or Ricean distribution.
Empirical coefficient values for indoor propagation.
Empirical measurements of coefficients formula_11 and formula_21 in dB have shown the following values for a number of indoor wave propagation cases.