Introduction to SEAMCAT
European Communications Office
Jean-Philippe Kermoal - SEAMCAT Manager (ECO)
December 2009
EUROPEAN
COMMUNICATIONS
OFFICE
Nansensgade 19
DK-1366 Copenhagen
Denmark
Telephone:
Telefax:
+ 45 33 89 63 00
+ 45 33 89 63 30
E-mail: [email protected]
Web Site: http://www.ero.dk
Outline
• Part 1 - Why SEAMCAT?
• Part 2 - SEAMCAT-3 software tool
• Part 3 - Principles of modelling various systems:
– Traditional – SEAMCAT 3.1.X
– CDMA – SEAMCAT 3.1.X
• Part 4 - SEAMCAT information
• Conclusions
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Part 1:
Why SEAMCAT?
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Spectrum engineering
challenges
increasing penetration of the
existing radio applications
regulatory
technological
introduction of new
radio applications economic considerations
The requirement for global compatibility amongst many
radio systems within a congested radio spectrum
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Need for spectrum sharing
• There are no more “empty” spectrum
• Proposed new systems have to find way of
“sharing” with some of existing systems
• Thus the need for spectrum engineering and
optimisation:
– to find which existing radio systems are easiest to
share with, and then
– determine the “sharing rules”
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Sharing methods
• Spacing radio systems in frequency
– Using the gaps between existing channels
• Spacing geographically
– Using the gaps between intended deployment areas
(e.g. cities vs. rural areas)
• Time sharing
– Exploiting different work time (day vs. night)
• Working at different power levels
– E.g. “underlay” spectrum use by UWB
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Sharing implementation
• Agile (cognitive) radio systems require
minimum sharing rules as they could be
adapting dynamically
– Simple example: finding free channel in a given
geographic area
• Traditional rigid-design radio system will
require precisely defined sharing rules
– Maximum transmit power, guard-bands to existing
systems, etc
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Defining the sharing rules
• Analytical analysis, usually by worst-case
approach:
– Minimum Coupling Loss (MCL) method, to establish
rigid rules for minimum “separation”
• Statistical analysis of random trials:
– The Monte-Carlo method, to establish probability of
interference for a given realistic deployment scenario
– That is where SEAMCAT comes into picture!
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The MCL approach
• The stationary worst-case is assumed
Wanted
Signal
Victim
Interferer
Dmin, or minimum frequency separation for D=0
– However such worst-case assumption will not be
permanent during normal operation and therefore sharing
rules might be unnecessarily stringent – spectrum use
not optimal!
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Monte-Carlo approach
• Repeated random generation of interferers and their
parameters (activity, power, etc…)
Wanted
Signal
t=t0
Victim
t=ti
t=t1
Active
Interferer
Inactive
Interferer
– After many trials, not only unfavourable, but also favourable
cases will be accounted, the resulting rules will be more “fair”
– spectrum use optimal!
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Monte-Carlo Assumption
• User will need to define the distributions of
various input parameters, e.g.:
– How the power of interferer varies (PControl?)
– How the interferer’s frequency channel varies
– How the distance between interferer and victim
varies, and many others
• Number of trials has to be sufficiently high
(many 1000s) for statistical reliability:
– Not a problem with modern computers
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Part 2:
SEAMCAT-3 Software tool
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History
• Developed in CEPT as a co-operation between
National Regulatory Administrations, ERO,
industry
• First released in Jan-2000, then gradually
developed in several phases
• Freely downloadable from ERO website
(www.ero.dk/seamcat)
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Purpose
• SEAMCAT is designed for:
– Generic co-existence studies between different
radiocommunications systems operating in same or
adjacent frequency bands
– Evaluation of transmitter and receiver masks
– Evaluation of various limits:
 unwanted emissions (spurious and out-of-band),
 blocking/selectivity, etc.
• Not designed for system planning purposes
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SEAMCAT tool
• Used for analysis of a variety of radio
compatibility scenarios:
– quantification of probability of interference between
various radio systems
– consideration of spatial and temporal distributions of
the received signals
• Can model any type of radio systems in
terrestrial interference scenarios
• Based on Monte-Carlo generation
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Typical examples of
modelled system
• Mobile:
– Land Mobile Systems
– Short Range Devices
– Earth based components of satellite systems
• Broadcasting:
– terrestrial systems
– DTH receivers of satellite systems
• Fixed:
– Point-to-Point and Point-to-Multipoint
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Installing SEAMCAT
On-line Webstart:
Internet connection is needed at least for the
installation; during later runs Internet used (if available)
to check for updated version
(Windows, Linux etc...)
Off-line
(Windows only)
• No special processor/memory needs
• Java RTE should be installed on your PC, at least version 1.6 required
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Software architecture
Plug-ins
Technical Library
User Interface
Workspace
(.sws)
Event Generation Engine
Results
XML File
CDMA Engine
Future Calculation Engine
Reports
XML stylesheets
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Interference Calculation Engine
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EGE Display
CDMA Display
Display
ICE Display
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Main interface
• Windows-oriented
• Data exchange via XML files
• Main element – workspace:
– Simulations input data – scenario:
 equipment parameters, placement, propagations
settings, etc. etc.
– Simulation controls: number of events etc
– Simulation results: signal vectors, Pinterference
– Physically - an XML file with “sws” extension
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SEAMCAT-3 software
• Conceived in early 2003
• Conceptually the same interface structure as in
•
•
•
•
SEAMCAT-2: workspace based, dialogue views
Main reason: need to model CDMA
Also: improvement of user interfacing and
general use convenience
Implemented in Java
Source code available upon request
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Graphic interface
• Shows positions of generated transceivers in
victim and interfering systems;
• Overview of results (dRSS, iRSS)
• Intuitive check of simulation scenario;
• Detailed insight into simulated data for
modelled CDMA system (last snapshot only);
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Extra features
• Propagation model plug-in API(Application
Programing Interface)
• Post processing plug-in API
• Batch simulation format (Automation of repetitive
compatibility studies to be run at once)
• Remote computing
(Public use of a powerful server at
ERO and possibility to set-up local SEAMCAT server)
• Custom simulation report
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(XSLT->XML style sheet)
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Plug-in
• A plug-in is a (little) software programme,
which may be developed by the user
• Written using standard Java language, compiled
using open development tools
• The pre-compiled code may be then “pluggedin” at certain “insertion points” of SEAMCAT
simulation flow to produce the desired “userdefined” functionality
• No perceivable impact on simulation speed
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Propagation
model plug-in
• This plug-in may be used to define ANY kind of
propagation model, no complexity limit
• The plug-in may be inserted at any point where
propagation model is defined in the scenario:
–
–
–
–
Victim link
Interfering link
Interference path
CDMA/OFDMA modules
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Post-processing plug-in
• This plug-in is invoked at the end of the
snapshot generation and may be used e.g.:
– Powerful API
– Introduce user-defined consistency checks
– Model some special system design features, e.g.
Smart Antennas, etc.
– Account for any additional environment features, e.g.
terrain/clutter impact, etc
– To save intermediate results into external files for
signal processing in other tools (Matlab, etc)
– not applicable to CDMA (victim)
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Remote computing
• To ease carrying out lengthy simulations
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Batch simulation
• “Batch” function allows automation of repetitive
compatibility studies by scheduling several
SEAMCAT simulations to be done in one run of
the programme
• Typical case – to study the impact of change of
any one (or few) scenario parameters on the
probability of interference
• Since version 3, any parameter (and any
number of them) could be varied in batch
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Part 3:
Principles of modelling various
systems
- ”Traditional” system
- CDMA system
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Main elements of
SEAMCAT scenario
Start
While
i=1,N
iRSS
A
Generate position data of Wt, Vr
Calculate dRSSi
dRSS
B
Victim
Receiver
(Vr)
Victim link
dRSS
vector
While
i=1,N
Interfering
Transmitter
(It)
C
While j=1,M
Interfering
link
Generate position data of Itj, Wrj
Calculate iRSSi,j
Wanted
Transmitter
(Wt)
Wanted
Receiver
(Wr)
D
Calculate iRSSiSUM
iRSS vector
dRSS, iRSS to ICE
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Creating simulations
scenario
• User defines a scenario, describing mutual
positioning of two systems in geographical
domain…
5 km
MS-Iti
Wti
Wr
BS-Vr
…as well as many other parameters
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Scenario parameters
•
•
•
•
•
Positioning of two systems in frequency
Powers
Masks
Activity
Etc.
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Event generation
• Random generation of transceivers
• Link budget
• Signal values
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How event generation
works*
• Succession of snapshots…
dRSS
WT
1) Calculate d, Ptx, GaTx, GaRx, L
2) Calculate dRSSi
VR
IT
iRSS
Snapshot#
WT
2) CalculateVR
iRSSi
Snapshot#
1) Calculate d, Ptx, GaTx, GaRx, L
1) Calculate d, Ptx, GaTx, GaRx, L
2) Calculate received signal, if PC, adjust Ptx
IT
WR
WR
(*) Except CDMA/OFDMA systems
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Results of event
generation
• Vectors for useful and interfering signals:
dRSS
iRSS
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Evaluating probability
of interference
dRSS -> (C)
- For each random event where
dRSS>sensitivity:
Desired signal value (dBm)
Interfering signal (dBm)
C/Itrial > C/Itarget?
Interference (dB)
iRSS -> (I)
Noise Floor (dBm)
- If C/Itriali >C/Itarget: “good” event
- If C/Itriali <C/Itarget: “interfered”
- Finally, after cycle of Nall events:
Overall Pinterference= 1- (Ngood/Nall)dRSS>sens
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CDMA modelling
• Modelling of CDMA systems as victim, interferer,
or both:
–
–
–
–
Voice traffic only;
Quasi-static time within a snapshot;
One direction at a time (uplink or downlink);
Particular CDMA standard defined by setting Link Level
Data (CDMA2000-1X, W-CDMA/UMTS)
• Impact of interference measured by excess
outage (capacity loss due to interference)
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CDMA procedure
1
Pre-simulation
This part of the GUI is used to assist the user when configuring the workspace.
All CDMA specific GUI elements are available as part of either VictimLink or InterferingLink configuration dialogs.
2
Simulation
The simulation GUI elements are shown during the simulation and are used to provide information about what SEAMCAT
is doing.
Since CDMA simulation can take much longer than non-CDMA simulations, there are special GUI parts used to provide
information to the user.
3
Results
4
Detailed information on the last snapshot
After a simulation these GUI parts are used to provide access to calculated results but also detailed insight into the last
snapshot of the simulation.
Inspecting the last snapshot is considered a good way to validate the configuration of the simulated workspace.
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• First a succession of snapshots are run
without interference, gradually loading the
system to find the target non-interfered
capacity per cell
Start
• Then the standard range of EGE snapshots
While i=1, N
is applied to generate the derived number
While j=1, L
of “target” users
Generate position data of Wt , Vr
• apply interference and note the impact in Iterative process of power balancing
in CDMA cells
terms of how many of initial users were
Record dRSS or other parameter,
e.g. non-interfered CDMA capacity
disconnected
j
j
i
CDMA as
interferer
C
While j=1, M
CDMA as
victim
While k=1, M
Generate position data of Itk, Wrk
Calculate iRSSi,k
Generate position data of Itj, Wrj
Repeat iterative process of power
balancing in victim CDMA cells, now
with iRSS present as external impact
Iterative process of power balancing
in CDMA cells
While j=1, M
Record impacti of interference, e.g.
loss of CDMA capacity
Calculate iRSSi,j
(N) records of
interference impact
D
To further engines
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CDMA: Power Control
• Modelled CDMA cell is surrounded by two
tiers of auxiliary cells, and total cluster of 19
(57 for three-sector deployment option) is
considered in power control tuning
• Application of Wrap-Around technique for
calculation of distance to closest BS produces
effect of “endless” uniform network
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Modelled CDMA cell
InterfererVictim distance
Other radio
system, counterpart in
interference
simulation
Modelled CDMA cell
Two auto-generated tiers
of auxiliary CDMA cells
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Clear legend
BS antenna display
BS or MS
info display
Last snapshot displayed
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General system info
Cell specific info
Connected - voice active user
Active link
Inactive link
Dropped user
CDMA interferer
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CDMA network-edge case
• Instead of centre cell, takes the cell at the
edge of CDMA PC cluster as a reference cell,
wrap-around formulas adjusted as if no other
cells are located beyond that cell
• This should be useful for e.g. cross-border or
similar interference scenarios
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Setting Network edge case
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CDMA results
Non-interfered capacity
(red)
Interfered capacity
(blue)
Difference
(green)
Number of connected UE
•
•
•
•
Initial capacity: Number of connected UEs before any external interference is
considered.
Interfered capacity: Results after external interference is applied.
Excess outage, users: How many UEs were dropped due to external interference.
Outage percentage: Percentage of UEs dropped due to external interference.
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CDMA results
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Part 4:
SEAMCAT information
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On-line manual
www.ero.dk/seamcat
www.seamcat.org/xwiki
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CEPT SEAMCAT workspace
publicly available
• Existing .sws files which have been generated as part of some
ECC report or CEPT reports activities can be found at
www.erodocdb.dk
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Reference material and
workspaces
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Conclusions
• Sharing rules are important element of spectrum
•
•
•
•
optimisation process
Unless some intelligent interference avoidance is
implemented in radio systems, the careful choice of
sharing conditions is the only means for achieving
successful co-existence and optimal spectrum use
Statistical tool SEAMCAT is a powerful tool for such
analysis
On-line manual
Existing CEPT SEAMCAT workspaces are publicly available
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Thank you - Any questions?
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