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An electromagnetic wave propagating along a path C has the phase shift over C as if it was propagating a path in a vacuum, length of which, is equal to the optical path length of C. Thus, if a wave is traveling through several different media, then the optical path length of each medium can be added to find the total optical path length.
The Hata model is a radio propagation model for predicting the path loss of cellular transmissions in exterior environments, valid for microwave frequencies from 150 to 1500 MHz. It is an empirical formulation based on the data from the Okumura model , and is thus also commonly referred to as the Okumura–Hata model . [ 1 ]
This model is the combination of empirical and deterministic models for estimating path loss in an urban area over frequency range of 800 MHz to 2000 MHz. [ 2 ] COST (COopération européenne dans le domaine de la recherche Scientifique et Technique) is a European Union Forum for cooperative scientific research which has developed this model ...
All these models had one thing in common: they all predicted very short average path length. [1] The average path length depends on the system size but does not change drastically with it. Small world network theory predicts that the average path length changes proportionally to log n, where n is the number of nodes in the network.
where is the large-scale (log-normal) fading, is a reference distance at which the path loss is , is the path loss exponent; typically =. [ 1 ] [ 2 ] This model is particularly well-suited for measurements, whereby P L 0 {\displaystyle PL_{0}} and ν {\displaystyle \nu } are determined experimentally; d 0 {\displaystyle d_{0}} is selected for ...
The log-distance path loss model is a radio propagation model that predicts the path loss a signal encounters inside a building or densely populated areas over long distance. While the log-distance model is suitable for longer distances, the short-distance path loss model is often used for indoor environments or very short outdoor distances.
The path loss in other frequency bands (medium wave (MW), shortwave (SW or HF), microwave (SHF)) is predicted with similar methods, though the concrete algorithms and formulas may be very different from those for VHF/UHF. Reliable prediction of the path loss in the SW/HF band is particularly difficult, and its accuracy is comparable to weather ...
L = The median path loss. Unit: decibel (dB). L 0 = The reference path loss along 1 km. Unit: decibel (dB). = The slope of the path loss curve. Unit: decibels per decade. d = The distance on which the path loss is to be calculated. Unit: kilometer (km). F A = Adjustment factor