Analyzing Path Loss in Urban and Suburban Environments

1
Analyzing Path Loss in Urban and Suburban
Environments

• By Mark Anderson
• EE233C
• Dr. Mani Srivastava

2
Link Analysis

• Link Budget
• Transmitter antenna gain
• Receiver antenna and amplifier gain
• Path Loss Free space, shadowing
• Slope-intercept approximation for far-field (gt 1
  m)

3
Outline

• Empirical Measurements
• Model Parameters
• Model
• Basic Model
• Simplifying
• At/Above/Below Avg Building Height
• Compare to Empirical Results
• Conclude

4
Empirical Shortcomings

• Empirical Data
• Measure signal response at a frequency per
  distance
• In specific sub/urban environment
• Pro
• Exact match for system under consideration
• Cons
• Expensive (mounting antennae, averaging
  fast-fade, expensive measuring equipment and
  personnel, multiple locations)
• Cant generalize (frequency, environment)

5
Model Dimensions
Base station
Mobile station
R
?
?hb
?hm
w
d
x
6
Simple Model

• Path Loss has three terms
• Free Space - Lfs
• Attenuation from distance to point source
• Diffraction, roof-to-street Lrts
• Edges of buildings diffract signal between
  buildings
• Diffraction, multiple Lmd
• Multiple diffractions further attentuate signal
  as it passes rows of buildings

7
Free Space

• Related to frequency and distance from base
  antenna
• Surface of sphere (far-field approximation)
• Point source approximation
• Ignore curvature

8
Roof-to-Street Diffraction

• Edges of building act as diffractors
• Both sides diffract down into street

9
Multiple-Diffraction

• Chained diffraction through rows of buildings
• QM is very complicated, with infinite summations
  of recursive functions
• Most simplifications of the model involve
  simplifying assumptions about QM

10
Choices for Base Antennae Location

• At Average Building Height
• Cheap (licensing, site availability, zoning)
• Limits range of antennae
• Above Average Building Height
• Expensive
• Best reception (least occlusion) (closest to LOS)
• Below Building Height
• Cheapest
• Increases in Network capacity from smaller cells

11
Coverage Examples

• Base antenna height has a strong effect on
  coverage patterns (8 m Bldg)

12
Near Rooftop Base Antennae
13
Above Rooftop Base Antennae
14
Below Rooftop Base Antennae
15
Comparison

• Near Rooftop
• Above Rooftop
• Below Rooftop
• Line of Sight (LOS)
• 20 dB/decade R and 20 dB/decade f

16
Empirical/Model Comparison

• Above Rooftops
• Antenna 100 ft
• 2 vs. 4-story
• 12 dB
• Close match for
• New Jersey (suburban)
• Tokyo/New York

17
Conclusion

• Good model
• Saves cost in estimating system buildout
• Accurate across various environments

18
Paper Figure