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
is the average multiplicative gain at the reference distance from the transmitter. This gain depends on factors such as carrier frequency, antenna heights and antenna gain, for example due to directional antennas; and
is a stochastic process that reflects flat fading. In case of only slow fading, it may have log-normal distribution with parameter 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 and in dB have shown the following values for a number of indoor wave propagation cases.| Building Type | Frequency of Transmission | ||
| Vacuum, infinite space | 2.0 | 0 | |
| Retail store | 914 MHz | 2.2 | 8.7 |
| Grocery store | 914 MHz | 1.8 | 5.2 |
| Office with hard partition | 1.5 GHz | 3.0 | 7 |
| Office with soft partition | 900 MHz | 2.4 | 9.6 |
| Office with soft partition | 1.9 GHz | 2.6 | 14.1 |
| Textile or chemical | 1.3 GHz | 2.0 | 3.0 |
| Textile or chemical | 4 GHz | 2.1 | 7.0, 9.7 |
| Office | 60 GHz | 2.2 | 3.92 |
| Commercial | 60 GHz | 1.7 | 7.9 |
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