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TRANSCRIPT
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PREDICTION MODELS
Anand Alexander
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By the end of this session, the participants will be able to:
Choose appropriate prediction models for different propagation
environments, topography, morphology and frequency ranges.
Objectives
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Okumura- Hata Model
Empirical Models:
- Okumura- Hata model
- Hata-Cost 231 model
- Walfisch-Ikegami model
- Keenan Motley model
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Okumura- Hata Model
HATA Model based upon 4 Environment Types and applies to:
Large Cells normally > 3km - High Sites Frequency, f: 150 - 1,000 MHz
Base Station Antenna Height, Hb: 30 - 200 m Mobile Antenna Height, Hm : 1 - 10 m
Transmission Path Length, d: 1 - 20 km
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Okumura- Hata Formula: Loss for Urban
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Land Cover Correction Factors (RACE Project)
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Okumura- Hata Model: Path Loss vs. Distance
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COST 231- Hata Model
900MHz GSM networks and other UHF/VHF services were modeled
successfully with the Hata formulae
1800MHz GSM frequencies became available within Europe, however
much less research had been carried out investigating the propagation of
higher frequencies. Empirical formula such as Hata was not available
The European Co-Operation in the field of Scientific and Technical
research (COST) developed the Hata formula further to include higher
frequencies (up to 2GHz)
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COST 231- Hata Model
COST 231 HATA Model is based upon the 4 Environment Types of Hata and applies to:
Large Cells normally > 3km
Frequency, f: 1,500 - 2,000 MHz
Base Station Antenna Height, Hb: 30 - 200 m
Mobile Antenna Height, Hm: 1 - 10 m
Transmission Path Length, d: 1 - 20 km
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COST 231- Hata Model: Loss Urban
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Exercise
Urban Environment
D = ?
Max Propagation Loss = 150dB
Given a UMTS Macro Urban Cellcalculate the Maximum Cell Uplink
Range given the following
parameters:
Base Station Height = 30m
Mobile Height = 1.5m
Frequency = 2GHz Maximum Loss (from a Link
Budget calculation) = 150dB
No in-building penetration
Use COST231 Hata Model
assuming a medium sized city
and/or sub-urban centres with
moderate tree density
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BTS Height and Path Loss Coefficient
Note that both Hata and COST 231 Hata have distance decay factors as:
[44.9 - 6.55 log 10 (Hb )] log 10 (d)
Base Station Height has the effect of varying decay rate
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Okumura Hata (Ericsson Variant)
A variant of the Okumura-Hata model has been developed by Ericsson. This
model can be used for rough estimations of the size of macro cells,
Lpathloss= A 13.82 log hb a(hm) + (44.9 6.55 log hb) log R
The cell range is the distance, R, corresponding to maximum allowed pathloss, Lpathmax. According to equation, the cell range is given by:
R =10 where
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Relationship between Path loss and Range
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Relationship between Path loss and Range
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Walfisch Ikegami Model
Hata and COST 231 Hata suited to cells having moderately high
base stations with cells in excess of 3km
For cells < 3km, and base station heights below 20m, particularly
microcells Hata models break down
Use of Walfish-Ikegami model for dense urban environments where
cell coverage is severely limited by clutter as with dense urban areas
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Walfisch Ikegami Model
Macrocellular Modelwhere Base Station height
> Average Rooftop Height,
but might be < highest
rooftop height
Based upon MultipleDiffractions from Rooftops
Diffraction and Reflection
mechanics dominate
Input variables relate to
geometry of environment
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Walfisch Ikegami Model
Frequency, f: 800 - 2,000 MHz
Base Station Antenna Height, Hb: 4 - 50 m
Mobile Station Antenna Height, Hm : 1 - 3 m
Transmission Path Length, d: 0.02 - 5 km
Also Considers
Height of buildings, HroofWidth of roads, wBuilding separation, bRoad orientation w,r.t to direct radio path, f( )
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Walfisch Ikegami Model
Line of Sight exists between base and mobile antennas:
Lb = 42.6 + 26logd + 20logf ; d > 20 m
Lb = Lo (free space loss)
Line of Sight exists between base and mobile antennas:
Lb = LFS + LMSD + LRSDS
(1) LFS free space loss
(2) LMSD multi-screen diffraction loss
(3) LRSDS roof-top-street diffraction loss
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Walfisch Ikegami Model
Without free Line-of-Sight between Base Station and Mobile Station:L
b= L
o+L
rts+ L
msd
Free space loss,
Lo
= 32.4 + 20.Log10(dkm) + 20.Log10 (fMHz)
Roof-top to street diffraction and scatter loss,
Lrts
= -16.9 - 10.Log10 (w) + 10.Log10 (f) + 20.Log10 (Hroof - Hm) + Lcriwith
Lcri
= -10 + 0.354. for 0
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Exercise
Calculate using the Walfish -Ikegami model, the path loss for UMTS working in
the 2GHz band:
a. For the NLOS conditions over a distance of 3 km, given f = 900 MHz, base
station antenna height is 31.5 m, mobile station antenna height is 1.5 m, building
height is 21.5 m, street width is 30 m, width of building is 20 m. The street
orientation is on the average 15 with respect to the radio path.
b. For the LOS conditions over a distance of 3 km
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Pico cell Models
Used when micro and macro cell networks cannot cope
with either signal strength or capacity requirements.
There are two types of Radio propagation in a pico cell:
LOS following a Rician distribution
NLOS following a Rayleigh distribution
Path Loss:
pWkFc
dL dB
4log20
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Suggested values of F and W in dB (IEEE report)
Building Type F(dB) W(dB)
Airport 15 4.0
Conference center 30 3.7
Hospital 11 3.6
Office 15 2.2
Parking garage 12 4.3
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General Planning Software Model (usedby Huawei)
Lp = K1 + K2logd + K3(hm) + K4log(hm) + K5log(Heff) + K6log(Heff) logd + K7diffn + Kclutter
The general planning software model expressions is:
K1-Constant related with the frequency (MHz);
K2-Constant related to the distance (km);
K3, K4-MS antenna height (m) correction factor;
K5, K6-BS antenna height (m) correction factor;
K7-Diffraction correction factor;
Kclutter-Ground fading correction factor;d-Distance between the BS and MS (km);
hm, Heff-Valid heights of the MS antenna and BS antenna (m)
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Clutter and K Parameters
0Urban
5Dense urban
-2.90Village
-2.50Parallel low build ings
-2.50Suburban
16High building
5.00Industrial & commercial area
13.00Forest
-1.00Rangeland
-2.00Open areas
-3.00Watery land
-3.0Inland water
Attenuatio
n
Clutter
0Urban
5Dense urban
-2.90Village
-2.50Parallel low build ings
-2.50Suburban
16High building
5.00Industrial & commercial area
13.00Forest
-1.00Rangeland
-2.00Open areas
-3.00Watery land
-3.0Inland water
Attenuatio
n
Clutter
-0.8K7
-6.55K6
-13.82
0.00
-2.49/800(urban)
-2.93/2000 (urban)
0/800 (large city,-
2.93/2000 (large city )
K3
44.9K
149/800 (urban),
162.5/2000 (Urban)
145/800 (big city)
165.5/2000 (big city)
K1 (MHz)
Parameter valueK parametername
-0.8
-6.55
-13.82K5
0.00K4
-2.49/800(urban)
-2.93/2000 (urban)
0/800 (large city,-
2.93/2000 (large city )
44.9K2
149/800 (urban),
162.5/2000 (Urban)
145/800 (big city)
165.5/2000 (big city)
Parameter valueK parametername
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Question and Answers
Discussion