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Propagation Modeling for Umts
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Commercial-in-Confidence
Propagation Modeling for UMTSPropagation Modeling for UMTS
Propagation Modeling for UMTS
Commercial-in-Confidence
ContentsContents• UMTS spectrum• Model types• Map data requirements• CW measurements• Model calibration exercise
Propagation Modeling for UMTS
Commercial-in-Confidence
Session AimsSession Aims• This session answers the following questions:
! What are the characteristics of a UMTS radio frequency?! What is a propagation model?! What are the main types of propagation model available?! What map data is required for a propagation model?! How do I calibrate a propagation model?
Propagation Modeling for UMTS
Commercial-in-Confidence
3rd Generation Spectrum Allocations3rd Generation Spectrum Allocations
1800 20501900 1950 20001850 2100 2150 2200
ITU(WARC-92)
Europe
Japan
Korea
USA
1885 1980 20102025 2110 2170 2200
1920 1980 20102025 2110 2170 2200
1920 1980 2110 2170
2110 21701920 1980
1850 1910 1930 1990 2110 2200
MSS MSSIMT-2000
Land Mobile
IMT-2000
Land Mobile UL
IMT-2000
Land Mobile UL
IMT-2000
Land Mobile
IMT-2000
Land Mobile DL
IMT-2000
Land Mobile DL
UMTS
Paired UL
UMTS
Paired DLUMTS
SATUMTS
SAT
UMTS
UnpairedUMTS
Unpaired
IMT-2000
Land Mobile
PCS
ULPCS
DLReserved
1900
DECTGSM 18001880
Propagation Modeling for UMTS
Commercial-in-Confidence
The UMTS Radio CarrierThe UMTS Radio Carrier• 5MHz bandwidth.• 200kHz Rasterised carriers.
! Centre frequency can be adjusted in 200kHz steps.
• Adjacent Channel Performance! Base Station
"ACLR1 = 45dBm"ALCR2 = 50dBm
! Mobile"ALCR1 = 21dBm"ALCR2 = 24dBm
fn fn+1 fn+2
Power level
ALCR2ALCR1
Power level Power
levelTX Power
5MHz
5MHz
5MHz
Propagation Modeling for UMTS
Commercial-in-Confidence
UK Spectrum AllocationsUK Spectrum AllocationsD D DE E EC C CA A A A B B B
Hutchison
One2One
Vodafone
BT Cellnet
Orange
14.6MHz 14.8MHz10MHz 10MHz 10MHz0.3MHz0.3MHz
20MHz
Propagation Modeling for UMTS
Commercial-in-Confidence
What is a propagation model?What is a propagation model?• A mathematical model used by computer planning tools to
predict coverage from a radio transmitter.! Typical inputs
" 3D terrain data" Land use data (Clutter)" Building outlines" Building heights
Propagation Modeling for UMTS
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Model Types (1)Model Types (1)Empirical (Statistical)
• Well understood. 2G standard.• Lower computational overhead.• Wide variety available.• Less accurate in small urban
cells. • Subjective clutter classification.• Only accurate in environment
where measurements were taken.
Deterministic (Ray tracing)• Few proven models available• Higher computational overhead• More map data required• More suited to small urban sites• Higher accuracy• Higher resolution
Propagation Modeling for UMTS
Street Canyon• More map data required• More suited to microcells
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Model Types (2)Model Types (2)• In practice, few planning tools use a single mode of model and most
are a hybrid of these methods.• Macrocell models are normally based on statistical techniques.• A large variety of Microcell models have been proposed.
Propagation Modeling for UMTS
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Statistical ModelsStatistical Models• Carrier wave measurements are
made from test transmitters.• The measurements are plotted
vs. log(distance).• A straight line is fitted through
the data.• A basic y=mx +c formula can be
used to estimate path loss.• The formula can be modified to
account for other factors eg. Txheight, Rx height & terrain effects.
Plot of measurements vs. log(distance)
Propagation Modeling for UMTS
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Deterministic ModelsDeterministic Models• The planning tool traces rays
from each site through an accurate 3D representation of an urban area.
• Typically a major component of the calculated path loss is free space loss.
• The effect of reflections diffraction and absorption due to buildings can be incorporated into the model.
Reflected rayDiffracted ray
Propagation Modeling for UMTS
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PopularPopular MacrocellMacrocell ModelsModels• Okumura - Hata
! Industry standard.! Not well suited for ranges under 1km.! Upper frequency limit 2GHz.
• Wavecall! Not so well accepted.! Fully deterministic no calibration required.! Suitable for urban macro and microcells.! Available for many common planning systems.
Propagation Modeling for UMTS
Commercial-in-Confidence
Popular Popular Microcell Microcell ModelsModelsPropagation Modeling for UMTS
Prediction Model Method Used Parameters 2D 3D Over Roof-top Required Data ResultsUniversity of Lund Dual Slope
Empirical− √ × × 2D Building
LayoutPath Loss
University of Karlsruhe Ray Launching Reflected +Penetrated Rays
√ × × 2D BuildingLayout
Path Loss + CIR
CNET Ray Tracing9 Reflections +Ground + Street
Diffraction√ × ×
2D BuildingLayout Path Loss
Swiss Telecom Ray Tracing Reflection +Diffraction
√ × × 2D BuildingLayout
Path Loss + CIR
Ericsson Mathematical − √ × WalfischIkegami Method
2D BuildingLayout
Path Loss
Telecom Street Canyon − √ × Walfisch BertoniMethod
2D BuildingLayout
Path Loss
Walfisch Ikegami Semi -Empirical − √ × WalfischIkegami Method
2D BuildingClasses
Path Loss
University of Valencia Ray TracingScattering +Diffraction
√ × Walfisch BertoniMethod
2D BuildingLayout +
Building Height
Path Loss
CNET Ray Launching Reflection +Diffraction
× √ × 3D BuildingLayout
Path Loss + CIR
ASCOM ETH Ray TracingReflection fromWall and Street × √ ×
2D BuildingLayout +
Building HeightPath Loss + CIR
University of Stuttgard Ray Launching6 Reflections + 2
Diffractions × √ ×2D Building
Layout +Building Height
Path Loss + CIR
University of Karlsruhe Ray TracingThe Most
Dominant Raysare Considered
× √ ×2D Building
Layout +Building Height
Path Loss + CIR
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Map data requirements (1)Map data requirements (1)• The minimum requirements for
map data are:! Height! Clutter
• Some propagation models also require building information:
! Building vectors! Building rasters
Propagation Modeling for UMTS
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Map data requirements (2)Map data requirements (2)• The resolution of map data will depend on several things.
! Budget" You can pay as much as you like for map data." Better data requires deeper pockets.
! Area type" Urban areas warrant higher resolution data (1 - 50 m)." Rural areas warrant lower resolution data (50 - 200 m).
! Model type" Microcell models require better data than Macrocell models." Macrocell models typically use 20 - 200 m." Microcell models typically require 1 - 20 m.
Propagation Modeling for UMTS
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Carrier Wave (CW) MeasurementsCarrier Wave (CW) Measurements• CW measurements are
accurate radio measurements used to calibrate propagation models.
• A number of temporary test sites are used for the test transmissions.
• Signal strength measurements and GPS fixes are made along predefined routes.
• These measurements must be averaged before they can be used for model calibration.
GPS
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CW Test SitesCW Test Sites• A typical network would require 3 different propagation models eg.
! Urban! Suburban! Rural
• Each model would require measurements from 10 - 15 test sites for calibration.
• The test sites used for propagation modeling should:! Be representative of typical cellular sites.! Should be free of obstructions.
Propagation Modeling for UMTS
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CW Test RoutesCW Test Routes• CW test routes must be planned carefully.• Routes must avoid:
! Elevated sections of road.! Cuttings.! Tunnels.! Bridges.
• Sufficient measurements must be made in each clutter type for the model to be valid.
• Typically the distances driven for each site would be in the order of! 80km per urban test site.! 160km per rural test site.
Propagation Modeling for UMTS
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CW Measurement EquipmentCW Measurement Equipment• Measurements should be distance based.
! Measurements should be taken no closer than 0.38λ.
• Equipment can be:! Distance triggered.! Time triggered.
• GPS outputs position every 1 second.! Position interpolation is required for each measurement.
• Test mobile measurements are NOT suitable.
Propagation Modeling for UMTS
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