The Empirical Formulation Of Radio Wave Propomentation Models
• They are empirical mathematical formulation for the characterization of radio wave propagation as a function of frequency, distance and other conditions.
• These models predict the path loss (i.e. the reduction in power density of an electromagnetic wave as it propagates through space or underground) of a transmitter and also the effective coverage area of transmitter.
We know that when a signal travels from a wireless channel, it undergoes various types of Propagation Effects like – Reflection, Diffraction and Scattering because of the presence of obstructions like buildings, mountains, hills etc.
Reflection is when the EM waves encroach on objects that are greater than the wavelength …show more content…
-It is very practical and is used in Japan in Modern Land Mobile Radio Systems.
• Demerits of this model:
-It has a slow response for rapid changes in terrain. Thus, it is fairly good in urban and sub urban areas but it is not so good in rural areas.
3. Hata model:
• This model is an Empirical Formulation of graphical path loss data that is given by Okumura.
• Its frequency range is 150 MHz – 1500 MHz.
• Its formulation is limited to only certain ranges of input parameters.
• Its formulations are applicable only for quasi smooth terrain.
• The mathematical expression is as follows : L (db) = 69.55 + 26.16fc - 13.82loghte - a (hre) + (44.96.55loghte) log10d
Carrier frequency: 150MHz≤ fc ≤1500MHz
Base station antenna height (hte): 30m ≤ hb ≤ 200m
Mobile unit antenna height (hre): 1m ≤ hm ≤ 10m
Transmission distance (d):1km≤ d ≤ 20 km
• The formulas have enhanced the practical value of Okumura Method but they do not include any path specific corrections.
• This model approximates the Okumura model for distances d > 1 Km. Thus; it is a good model for first generation cellular systems.
4. Cost 231