Radio propagation model - AbsoluteAstronomy.com

A radio propagation model, also known as the Radio Wave Propagation Model or the Radio Frequency Propagation Model, is an empirical

Empirical

The word empirical denotes information gained by means of observation or experimentation. Empirical data are data produced by an experiment or observation....

mathematical formulation

Formulation

Formulation may refer to:* Clinical formulation* Formulations * Formulation science* Pharmaceutical formulation:** Galenic formulation* Pesticide formulation...

for the characterization of radio wave propagation as a function

Function (mathematics)

In mathematics, a function associates one quantity, the argument of the function, also known as the input, with another quantity, the value of the function, also known as the output. A function assigns exactly one output to each input. The argument and the value may be real numbers, but they can...

of frequency

Frequency

Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...

, distance

Distance

Distance is a numerical description of how far apart objects are. In physics or everyday discussion, distance may refer to a physical length, or an estimation based on other criteria . In mathematics, a distance function or metric is a generalization of the concept of physical distance...

and other conditions. A single model is usually developed to predict the behavior of propagation for all similar links under similar constraints. Created with the goal of formalizing the way radio waves are propagated from one place to another, such models typically predict the path loss

Path loss

Path loss is the reduction in power density of an electromagnetic wave as it propagates through space. Path loss is a major component in the analysis and design of the link budget of a telecommunication system....

along a link or the effective coverage area of a transmitter

Transmitter

In electronics and telecommunications a transmitter or radio transmitter is an electronic device which, with the aid of an antenna, produces radio waves. The transmitter itself generates a radio frequency alternating current, which is applied to the antenna. When excited by this alternating...

Characteristics

As the path loss encountered along any radio link serves as the dominant factor for characterization of propagation for the link, radio propagation models typically focus on realization of the path loss with the auxiliary task of predicting the area of coverage for a transmitter or modeling the distribution of signals over different regions.

Because each individual telecommunication link has to encounter different terrain, path, obstructions, atmospheric conditions and other phenomena, it is intractable to formulate the exact loss for all telecommunication systems in a single mathematical equation. As a result, different models exist for different types of radio links under different conditions. The models rely on computing the median path loss for a link under a certain probability that the considered conditions will occur.

Development methodology

Radio propagation models are empirical in nature, which means, they are developed based on large collections of data collected for the specific scenario. For any model, the collection of data has to be sufficiently large to provide enough likeliness (or enough scope) to all kind of situations that can happen in that specific scenario. Like all empirical models, radio propagation models do not point out the exact behavior of a link, rather, they predict the most likely behavior the link may exhibit under the specified conditions.

Variations

Different models have been developed to meet the needs of realizing the propagation behavior in different conditions. Types of models for radio propagation include:

Models for indoor applications
Models for outdoor applications
- Ground wave
  Surface wave
  In physics, a surface wave is a mechanical wave that propagates along the interface between differing media, usually two fluids with different densities. A surface wave can also be an electromagnetic wave guided by a refractive index gradient...
  
  propagation models
- Sky wave propagation models
- Environmental Attenuation models
- Point-to-Point propagation models
- Terrain models
- City Models

Models for outdoor attenuations

Near-earth propagation models
- Foliage models
  - Weissberger's modified exponential decay model
    Weissberger's Model
    Weissberger’s modified exponential decay model, or simply, Weissberger’s model, is a radio wave propagation model that estimates the path loss due to the presence of one or more trees in a point-to-point telecommunication link...
  - Early ITU Model
    Early ITU Model
    The ITU Vegetation Model is a radio propagation model that estimates the path loss encountered due to the presence of one or more trees inside a point to point telecommunication link...
  - Updated ITU model
    - One Woodland Terminal Model
      One Woodland Terminal Model
      The ITU Terrestrial Model for One Terminal in Woodland is a Radio propagation model belonging to the class of Foliage models. This model is a successor of the Early ITU Model.-Applicable To / Under Conditions:...
    - Single Vegetative Obstruction Model
      Single Vegetative Obstruction Model
      The ITU Single Vegetative Obstruction Model is a Radio propagation model that quantitatively approximates the attenuation due to the vegetation in the middle of a telecommunication link.-Applicable to/under conditions:...
- Terrain models
  - Egli Model
    Egli Model
    The Egli Model is a terrain model for radio frequency propagation. This model, which was first introduced by John Egli in his 1957 paper, was derived from real-world data on UHF and VHF television transmissions in several large cities. It predicts the total path loss for a point-to-point link...
  - Longley–Rice model
    Longley–Rice model
    The Longley–Rice model is a radio propagation model: a method for predicting the attenuation of radio signals for a telecommunication link in the frequency range of 20 MHz to 20 GHz.Longley-Rice is also known as the irregular terrain model...
  - ITU Terrain Model
    ITU Terrain Model
    The ITU Terrain Loss Model is a radio propagation model that provides a method to predict the median path loss for a telecommunication link. Developed on the basis of diffraction theory, this model predicts the path loss as a function of the height of path blockage and the First Fresnel zone for...
- City models
  - Young Model
    Young Model
    Young model is a radio propagation model that was built on the data collected on New York City. It typically models the behaviour of cellular communication systems in large cities.-Applicable to/under conditions:...
  - Okumura Model
    Okumura Model
    The Okumura model for Urban Areas is a Radio propagation model that was built using the data collected in the city of Tokyo, Japan. The model is ideal for using in cities with many urban structures but not many tall blocking structures. The model served as a base for the Hata Model.Okumura model...
  - Hata Model for Urban Areas
    Hata Model for Urban Areas
    In wireless communication, the Hata Model for Urban Areas, also known as the Okumura-Hata model for being a developed version of the Okumura Model, is the most widely used radio frequency propagation model for predicting the behaviour of cellular transmissions in built up areas...
  - Hata Model for Suburban Areas
    Hata Model for Suburban Areas
    The Hata Model for Suburban Areas, also known as the Okumura-Hata model for being a developed version of the Okumura Model, is the most widely used model in radio frequency propagation for predicting the behavior of cellular transmissions in city outskirts and other rural areas...
  - Hata Model for Open Areas
    Hata Model for Open Areas
    The Hata Model for Open Areas, also known as the Okumura-Hata model for being a developed version of the Okumura Model, is the most widely used model in radio frequency propagation for predicting the behavior of cellular transmissions in open areas. This model incorporates the graphical information...
  - COST Hata model
  - Area to Area Lee Model
    Area to Area Lee Model
    Lee Model for Area-to-Area Mode is a Radio propagation model that operates around 900 MHz. Built as two different modes, this model includes an adjustment factor that can be adjusted to make the model more flexible to different regions of propagation....
  - Point to Point Lee Model
- Band-specific models
  - 2.4 GHz (ISM Band, of particular interest for WiFi)
    - Green-Obaidat
      Mohammad S. Obaidat
      Mohammad Salameh Obaidat is a computer science/engineering academic and scholar, the President of and a Fellow of the Society for Modeling and Simulation International , and a Fellow of the Institute of Electrical and Electronics Engineers ....
      
      Model

Models for indoor attenuations

ITU Model for Indoor Attenuation
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...
Log-distance path loss model

Models for environmental effects

Rain attenuation model
- ITU rain attenuation model
- ITU rain attenuation model for satellites
- Crane global model
- Crane two-component model
- Crane model for satellite paths
- DAH model

Models for antenna/environment effects

Classical (antenna gains are orthogonal to propagation effects)
Directional beam scattering
- Greenstein-Erceg
- Environmental Directivity Antenna Model (EDAM)

External links

The following external references provide practical examples of radio propagation concepts as demonstrated using software built on the VOACAP model.

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