- Other Types of Propagation Models
- Topographic models
- Use topographic databases or models of transmission path

to estimate received power - Examples: Longley-Rice/ITS, Durkin's

- Use topographic databases or models of transmission path
- Parametric models
- Use parameters that describe propagation environment

to estimate average received powers - Parameters include antenna heights, terrain type,

building heights, street widths - Examples: Okumura, Hata, Walfisch, PCS Microcell

- Use parameters that describe propagation environment

- Topographic models

- Valid for f: 40 MHz
60 GHz
- Techniques
- Geometric optics (i.e., 2-ray ground-reflection model)
- Knife-edge diffraction
- Far-field scatter
- Van der Pol-Bremmer far-field diffraction

- Modes of operation
- Point-to-point mode: uses detailed terrain path profile
- Area mode: estimates path-specific parameters

- Modifications
- For urban areas,
*urban factor (UF)*used to account

for urban clutter

- For urban areas,

- Techniques
- Uses topographic database
- Ignores off-radial reflections (no multipath propagation)
- Classifies paths in 3 ways
- LOS with no obstructions in 1st Fresnel zone
- LOS with inadequate 1st Fresnel zone clearance (6 dB loss)
- No LOS path: (1,2,3, >3 diffraction edges)

- Advantages
- Can read digital elevation map & produce signal strength contour

- Does not predict propagation effects due to foliage,

buildings, multipath

- Widely used for signal prediction in urban areas
- Applicable for:
- frequency
*f*: 150 MHz 1920 MHz - distance
*d*: 1 km 100 km - transmit antenna height
*h*_{te}: 30 m 1000m

- frequency
- Based on extensive measurements
- Technique
- Find free space path loss,
*L*_{F} - Determine median attenuation relative to free space
*A*_{mu}(*f*,*d*)

from curves - Add other correction factors for antenna heights and terrain

- Optional correction factors can be used, including terrain undulation height, isolated ridge height, average terrain slope, and mixed land-sea parameter

- Find free space path loss,

- Empirical formulation of Okumura loss data
- Applicable for:
*f*: 150 MHz 1500 MHz,*h*_{te}: 30 m 200 m,

*h*_{re}: 1 m 10 m - Standard formula for urban areas is

where*a*(*h*_{re}) is a correction factor for effective mobile antenna height, and depends on coverage area - Similar formulas (3.85), (3.86) are available for suburban

and rural environments - Valid for large-cell systems, but not PCS systems
- Has been extended to 2 GHz by European Co-operative for Scientific and Technical research (EURO-COST-231 Model)

- Known as Walfisch-Bertoni or Walfisch-Ikegami Model
- Models losses in urban environment
- free space loss
*L*_{f} - rooftop-to-street loss
*L*_{rts}- depends on street widths, frequency, height of reflection relative to receive antenna, and angle of incidence relative to street

- multiscreen diffraction loss due to rows of buildings
*L*_{ms}- depends on distance between buildings, frequency,

height of reflection and antennas, and propagation distance

- depends on distance between buildings, frequency,

*L*_{50}=*L*_{f}+*L*_{rts}*L*_{ms}

- free space loss
- See
*IS-95 CDMA and cdma2000*by Vijay Garg

- Uses 2-ray ground-reflection model for LOS microcells
- Uses log-distance model for obstructed (OBS) environment

(n: 2.56 2.69, : 7.67 9.31)

- Indoor propagation is affected by the same mechanisms as outdoors: reflection, diffraction, scattering
- Indoor conditions lead to more variation in signal levels
- Increased variation is caused by many factors in indoor
environment, including sensitivity to
- building materials and construction
- antenna placement
- doors opened or closed

- In general, indoor channels are classified as LOS or OBS

- For OBS channels, the propagation losses depend on the materials of the partitions and obstacles the signal passes through
- These
*partition losses*are categorized into same-floor

and between-floor losses - These losses are tabulated in tables 3.3-3.5 in the book
- Examples of same-floor losses
- Concrete wall: 18-15 dB @ 1300 MHz
- Sheetrock (2 sheets): 2 dB @9.6 GHz
- Dry Plywood: 1 dB @9.6 GHz
- Wet Plywood: 19 dB @9.6 GHz
- Aluminum (1/8 in): 47 dB @9.6 GHz

- Can also quantify partition losses between floors
*FAF*= floor attentuation factor (in dB)- Typical values of FAF for Office Building:
FAF, 915 MHz FAF, 1900 MHz 1 Floor 13.2 26.2 2 Floors 18.1 33.4 3 Floors 24.0 35.2 4 Floors 27.0 38.4 5 Floors 27.1 46.4 - *** Note that attenuation caused by one floor >> attenuation
caused by additional floors

- Log-distance path model is valid for many indoor environments
- Values of parameters have been measured for different types of
buildings
- Typical parameter values:
Building Frequency (MHz) *n*(dB) Retail Sore 914 2.2 8.7 Office, Hard Partition 1500 3.0 7.0 Office, Soft Partition 900 2.4 9.6 Suburban Home 900 3.0 7.0

- Modifies log-distance model for multiple-floor propagation
- Method 1

where*n*_{SF}= same-floor path-loss exponent - Method 2
- eliminates FAF by making path-loss exponent depend on # of
floors

where*n*_{MF}is the multi-floor path loss exponent

- eliminates FAF by making path-loss exponent depend on # of
floors
- Typical values of
*n*_{SF},*n*_{MF}:Same Floor 3.0 Through One Floor 4.19 Through Two Floors 5.04 Through Three Floors 5.22

- Signal strength increases with height (less attenuation due to
urban clutter)
- Typically 7.6
16.4 dB penetration loss on ground
floor
- Penetration loss decreases at about 2 dB/floor until about the
9th, and then increases
- Penetration loss in front of windows 6 dB < than locations with no windows

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