Clutter

Report
ATDI
Propagation Models in
ICS telecom
Webinar aim:
identify which radio propagation models
are implemented in ICS telecom
Including:
• Propagation model limitations
• Clutter settings
• What calculations take place
• Identifying the most appropriate model
• Examining the useful / popular radio propagation models
nb. Due to time constraints the lesser known radio
propagation models including corrections such as rain, gas
and reflections will not be covered.
Webinar aim:
present propagation models in a
similar form to ITU-R P.1144-5
Method Application
Type
Output Frequency Distance
% time
% location Terminal
height
Input data
ATDI
implementation
& comments
Name of Where the Point- Field
Valid
Valid
% time
% locations Valid
Data
Comments on
Method application tostrength, frequency distance factored
factored
range of required to implementation
in ICS
is used eg. point pathloss range of
(s)
into
into
terminal operate the in ICS Telecom
Telecom Broadcast, or
operation
calculation calculation heights propagation
areonautical point
calculation
etc
to
area
A guide to radio propagation models in ICS telecom
will be published shortly.
Definitions
•
•
•
•
Digital Terrain Model (DTM) – bare ground height – man-made modifications
tend to be ignored such as cuttings and embankments, etc
Clutter – What is on the bare ground including trees, buildings (suburban,
urban)
Absorption
Power absorbed by obstacle
Diffraction
Diffraction loss
•
•
T = transmitter
R = receiver
How clutter is used
Clutter code 9
Used for “building
layers” – not covered
in this presentation
Applies factor to clutter
height ie, if forrest 15m
high diffraction point
= 0.6 x 15 = 9m
dB/km applied every time
clutter is in transit
Flat attenuation
Applied only at
Receiver pixel
Clutter height
Applied at all locations
Clutter settings
Clutter
RX
RX
T/R over ground
spot
T/R over ground
relaxed
Over
Clutter
Over
Ground
Clutter
Ground
General Concept
Represents pixel of clutter urban
Represents pixel of ground (DTM)
Represents pixel of ground (DTM)
Represents pixel of clutter suburban
Represents pixel of clutter urban
Diffraction loss
From last diffraction
point
Represents pixel on ground (DTM)
Represents pixel of clutter urban
with clutter height x and dB/km y
Absorption loss = 4 x y / DTM raster size
Clutter attenuation = MIN (diffraction loss , absorption loss)
Clutter attenuation = Diffraction loss + Absorption loss
dB/km
Diffraction loss
from last diffraction
point
A
B
Flat attenuation
Absorption loss = 4 x y / DTM raster size
At Location A (RX height > Clutter height)
Clutter attenuation = MIN(Diffraction loss , Absorption loss)
Clutter attenuation = Diffraction loss + Absorption loss
At Location B (RX height < Clutter height)
Clutter attenuation = MIN(Diffraction loss , Absorption loss) + Flat attenuation
Clutter attenuation = Diffraction loss + Absorption loss + Flat attenuation
Diffraction loss
from last diffraction
point
10dB
Flat + absorption
10dB
Represents pixel of ground (DTM)
Represents pixel of clutter urban
with clutter height x and dB/km y
Clutter attenuation = MIN (Diffraction loss , Absorption loss = summation of flat loss for
each separate obstacle)
Clutter attenuation = Diffraction loss + Absorption loss which is summation of flat loss for
Each separate obstacle
Clutter height 8m
Clutter height 30m
10dB
Diffraction loss
Only if RX > clutter height
Flat + diffraction mode
If RX height < Clutter height Clutter loss = diffraction + clutter attenuations
into RX pixel)
Clutter might be used to identify
Roof tops / street levels
Clutter not used in calculation
Clutter when using
DSM or DEM
Other Clutter modes
• CCIR and UER are similar to flat + diffraction, except with standard values
for mobiles (CCIR) and TV reception (UER)
• TSB-88 Mode (NTIA report TSB-88-B similar to flat + diffraction except
clutter attenuation need to change with frequency (clutter height should
be set to zero)
• USER same as flat + diffraction except where RX height > clutter height in
which case it is diffraction + flat attenuation into last pixel
Clutter code 9 has a specific role and is used as identification for building
layer
Building layers are not covered in this webinar
Demonstrate best way to test clutter settings and attenuations.
DEMO
Radio Propagation Models
• Main Models
–
–
–
–
–
ITU-R 525/526 Deygout
ITU-R 525/526 Bullington
ITU-R 1546-3
ITU-R 1812-2
ITU-R 452
• Other Useful Models
– Okumura/ Hata / Davids
– ITU-R 528 (optional add on)
These models will be covered in detail during this webinar.
•
•
Other models
– Fresnel method +
– Wojnar method
– Wein method
– ITU-R 370
– ITU-R 1225
– Medium Frequency
– 3GPP – LTE Rural
– 3GPP – LTE urban
– SUI method
– Hata – Cost 231
– Cost 231 Open
– Skywave LF & MF
Add-on models
– Itm122 - Irregular Terrain Model
– ITM_NTIA Longley Rice (ITM)
– Ground wave – ITU-R P368-7
– RRC04
– Skywave ITU-R P.435, ITU-R P.1147
– Tropospheric Scatter
These models will not be covered
during the webinar . The applicability
of these models will be covered in the
Guide to Radio Propagation models
ICS Telecom / HTZ Warfare Radio
Propagation model settings
• In concept
Some propagation models do not
split into these 3 conditions easily;
in some cases they do not apply
TX
Location
RX Location(s)
ITU-R 525 / 526 Deygout
• Standard model in ICS telecom since version 1
• Three worst-case intrusions into the Fresnel zone
taken into account
• ATDI updated method with Deygout94 diffraction where
multiple intrusions are taken into account
• The ITU have now updated method
Method
Rec ITU-R
P.525
Rec ITU-R
P.526-11 and
earlier
Application
Type
All services
Point-topoint
Point-topoint
All services
Output
Frequency
Field strength 100 MHz to
100 GHz
Field strength 30 MHz to
100 GHz
Distance
% time
Not specified Not
applicable
Radio
Not
horizon
applicable
(50% time
only)
% location
Not
applicable
Not
applicable
Terminal height
No Limits
specified
No Limits
specified
Input data
Frequency
Distance
Path profile data
Frequency
Distance
ATDI implementation &
comments
Implemented
Implemented, This
model takes into
account a maximum
of 3 intrusions into
the Fresnel zone and
is a Dygout model
ITU-R 525/526-12 Bullington
• 526 model uses the following parts of 526-12
– Spherical earth section 3.2
– Bullington model section 4.5
• Rounded earth, knife edge,
multiple obstacles , smooth earth
not implemented because it causes
discontinuities as models switch
Bullington model uses single
effective Diffraction point
Method
Rec ITU-R
P.525
Rec ITU-R
P.526-12 and
latter
Application
Type
All services
Point-topoint
Point-topoint
All services
Output
Frequency
Field strength 100 MHz to
100 GHz
Field strength 10 MHz to
100 GHz
Distance
% time
Not specified Not
applicable
Radio
Not
horizon
applicable
(50% time
only)
% location
Not
applicable
Not
applicable
Terminal height
No Limits
specified
No Limits
specified
Input data
Frequency
Distance
Path profile data
Frequency
Distance
ATDI implementation &
comments
Implemented
Implemented, This
model takes into
account the worst
intrusions and
develops and single
representative
intrusion and uses
Bullington model
ITU-R 452
• Point to Point calculation
• Based on ITU-R P. 525 / 526-10 (Deygout)**
• For 50 to 0.001% time
• Settings must be correct in ICS telecom
• 2 clutter variables in the calculation ha and dk.
– - ha is set in clutter heights
– dk value applied is based on clutter code
Method
Rec. ITU-R
P.452
Application
Type
Services
Point-toemploying point
stations on
the surface
of the Earth;
interference
Output
Path loss
Frequency
100 MHz to 50
GHz
Distance
% time
Not specified
but up to
and beyond
the radio
horizon
0.001 to 50
Average year
and worst
month
% location
Not
applicable
** Note this will be changed to Bullington in near future
Terminal height
Input data
No limits specified Path profile data
Frequency
Percentage time
Tx antenna height
Rx antenna height
Latitude and
longitude of Tx
Latitude and
longitude of Rx
Meteorological data
ATDI implementation &
comments
Implemented. Note
do NOT tick “Flat
earth profile sent to
DLL”
The codes 2,3,4,5,8,10 are fixed for a given clutter
e.g. if you have coniferous trees it must be code 8 , then fill in height = 20m.
Similarly, .dk is derived from a lookup – DON’T enter it.
If clutter code=8 (Coniferous trees), dk=0.05;
If clutter code=5 (Tropical rain forest), dk=0.03;
If clutter code=2, 3 or 4 (Urban), dk=0.02;
If clutter code=10 (Industrial zone), dk=0.05.
For the remaining clutters, fill in the heights and it will use the corresponding value of dk:
If clutter height=4m, dk=0.1;
If clutter height=5m, dk=0.07;
If clutter height=15m, dk=0.05;
If clutter height=9m, dk=0.025;
If clutter height=12m, dk=0.02;
If clutter height=25m, dk=0.02;
ha must be set in the clutter dialogue box
MUST be un-ticked
ITU-R P.453 (Fig 1,2) or 452-14 (Fig 13)
ITU-R P.453 (Fig 4-7) or P. 452-14 (Fig 11)
Recommended clutter settings based on
452-14 Table 4
ATDI recommends that
ATDI standard clutter
designations are used
Note 1: Clutter level 6 must be sea / water
Note 2: Ofcom has modified version of Infotera Clutter to use with P.452 model.
ITU-R 1546
•
•
•
•
•
Broadcast / International Coordination / Interference
Related to ITU-R 370
Only considers terrain within 15km of transmitter
Uses clutter and takes off angle to modify prediction
Uses propagation curves for different frequencies / %
time
• Not symmetrical (loss A  B  Loss B  A )
If not standard then ATDI clutter codes
will need to be set up
Method
Rec. ITU-R P.1546
Application
Terrestrial
services
Type
Output
Frequency
Point-to-area Field strength 30 to 3 000 MHz
Distance
1 to 1 000
km
% time
1 to 50
% location
1 to 99
Terminal height
Input data
ATDI implementation &
comments
Tx/base: effective Terrain height and
Implemented. Clutter
height from less
ground cover
needs to be loaded
than 0 m to 3 000 (optional)
and clutter heights
m
Path classification
and calculation
Rx/mobile: ³1 m
Distance
method defined. This
Tx antenna height
has also been
Frequency
extended for GE06
Percentage time
(separate DLL file) use
Rx antenna height
with warm/cold sea
Terrain clearance
definition. Note this
angle
model in nonPercentage locations reciprocal
Refractivity gradient
ITU-R 1812-2
• This is a combination of ITU-R P.452, P525,
P526-12 and is for point to area calculations
• This is the only propagation model that takes
clutter into account at both ends of the path
Method
Application
Rec. ITU-R P.1812
Terrestrial
services
Type
Output
Frequency
Point-to-area Field strength 30 MHz to 3 000
MHz
Distance
% time
Not
1 to 50
specified but
up to and
beyond the
radio
horizon
% location
1 to 99
Terminal height
No limit
Input data
ATDI implementation &
comments
Path profile data
Frequency
Percentage time
Tx antenna height
Rx antenna height
Latitude and longitude
of Tx
Latitude and longitude
of Rx Meteorological
data
Implemented. Clutter
heights need to be
defined for mid path
clutter height, Clutter
values used with
terminal heights from
table 2 as standard for
terminal clutter losses
ITU-R P.1812-2
Terminal clutter height is related
to Clutter code
(ITU-R P.1812-2 Table 2)
ATDI Clutter
code
6
0
1
2,3,4,5,8
7
Okumura Hata
• Mobile operators tend to use this model and fine tune it
with drive tests
• Model is based on clutter not terrain, so is designed for
small ranges
The extended Hata model has not been
implemented yet. If required please let ATDI
know. NB. this model is for SRD with ranges in
meters and for indoor and outdoor.
To use this model effectively on a DTM a high
resolution map would be required (1 -5 m /
pixel)
Propagation Regions
• Line of sight
(LOS)
Loss
Distance
• Diffraction
• Tropospheric
Note: This propagation model is an add on to ICS Telecom and needs to be
Purchased separately
Other Corrections to
Propagation Models
• Rain - World based on ITU-R P.538 and UK rain on Ofcom data
• Snow – Isotherm level (level at which water freezes) if path passes
though this level this correction is applied
• Fog – ITU-R 840
• Gas – ITU-R 676 (Note ITU-R F.1820 is Gas attenuation from HAP at
47GHz)
• Wave height - (applies an effective clutter height depending on wind
strength)
• Reflections
Comparison of Radio Propagation
models in ICS telecom
DEMO
Thank you for attending today
Any questions?
ATDI Limited
The Beehive – City Place – Gatwick
West Sussex – RH6 0PA – UK
Tel +44 (0)1293 522052 - Fax +44 (0)1293 522521
Email: [email protected]

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