PROPAGATION MODELS
INDOOROUTDOOR
LOG-NORMALLOG-DISTANCE
BASIC DIVISION
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
Outdoor Propagation Models There are a number of mobile radio propagation
models to predict path loss over irregular terrain.
These methods generally aim to predict the signal strength at a particular sector.
But they vary widely in complexity and accuracy.
These models are based on systematic interpretation of measurement data obtained in the service area.
OUTDOOR APLLICATION MODELS
Ground wave 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 Early ITU Model Updated ITU model
One Woodland Terminal Model Single Vegetative Obstruction Model
Terrain models Egli Model Longley–Rice model ITU Terrain Model
Examples City models
Young Model Okumura Model Hata Model for Urban Areas Hata Model for Suburban Areas Hata Model for Open Areas COST Hata model Area to Area Lee Model Point to Point Lee Model
Band-specific models 2.4 GHz (ISM Band, of particular interest for WiFi)
Green-Obaidat Model[1
Examples of Outdoor Models
Longley-Rice Model Durkin’s Model Okumura’s Model Hata Model PCS extension to Hata Model Walfisch and Bertoni
Indoor Propagation ModelsIndoor Propagation Models
Indoor radio channel differs from traditional mobile radio channel in: distances covered are much smaller variability of the environment is greater for a much
smaller range of T-R separation distances
It is strongly influenced by specific features, such as layout of the building construction materials building type
Models for indoor attenuations
ITU Model for Indoor Attenuation
Log-distance path loss model
Log-Normal Distribution
It describes the random shadowing effects which occur over a large number of measurement locations which have the same T-R separation,but have different levels of clutter on the propagation path.
The random effects of shadowing are accounted for using the Gaussian distribution
In practice, the values of n and σ are often computed from measured data, using linear regression
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QdP rr
The probability that the received signal level will exceed a certain value γ can be calculated from the cumulative density function as
Can be used to determine the percentage of coverage area in cellular systems.
Applications
•Both theoretical and measurement-based propagation models indicate that average received signal power decreases logarithmically with distance, whether in outdoor or indoor radio channels.
• The average large-scale path loss for an arbitrary T-R separation is expressed as a function of distance by using a path loss exponent, n.
Penetration Thru Buildings/ Log-Distance Path Loss Model
UNIT - 2
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