‘One Sky for Europe’
EUROCONTROL
© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
AAeronautical eronautical CCommunications ommunications
TTechnologies echnologies SSimulatorimulator
Bertrand Desperier - EEC [email protected]
Patrick Delhaise - Eurocontrol DAS/CSM [email protected]
‘One Sky for Europe’
EUROCONTROL
© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
Simulating the air/ground sub-network
(i.e physical and data-link layers in OSI model)
A modular architecture for re-using parts
First development for VDL mode 2
Multi platform supported (currently PC under windows)
OVERVIEWOVERVIEW
Adaptation and validation of key air/ground sub-network
Prediction of system performance and capacity limits.
Optimisation of parameters, standards function, and implementation aspects
respecting operational requirements
‘One Sky for Europe’
EUROCONTROL
© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
Area to be studied
PrinciplePrinciple
CommunicationChannels
Station 1
Station 3
Station N
Station 2
Capacity/ Reliability Analyser
AIR TRAFFIC INPUT
MSG INPUT-Random-Deterministic
Frequen
cy
Time
GS1
SYSTEM PARAMETERS
GS2
GS3
‘One Sky for Europe’
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© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
Relative channelsRelative channels
AC 1
AC 2
AC 3
1/31/2
2/3
2/3
1 2 3
Each station perceives differently the common channel at a given time
1/2
1/3
t(AC 3)
Absolute time
t(AC 2)
t(AC 1)
Level
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CHANNEL FILTER
STATION (AC or GS)
SYSTEM
Generic ArchitectureGeneric Architecture
Channel
Upper layersMessages
Air traffic System parameters
Relative channel information
‘One Sky for Europe’
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© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
Upper layersMessages
Air traffic
AnalyseCapacityreliability
Average delay ...
CHANNEL FILTER
STATION (AC or GS)
System parameters
Channel Monitor
Relative position calculator
Propagationmodel
Power
Delay
Data
Rx
Transmitter
Data Link
SYSTEM
Generic ArchitectureGeneric Architecture
Receiver
Channel
‘One Sky for Europe’
EUROCONTROL
© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
InputsInputs Air traffic
For each station (airborne and ground) 3-D positions in a given area
Can be extracted from any air traffic simulator
(RAMS, TAAM, SAAM…) or radar plots record Messages profiles
Messages transmission rate distribution Message length distribution Messages exchange based on events
System parameters Propagation model (several accuracy levels) Physical layer Medium access control layer
Data-link layer
‘One Sky for Europe’
EUROCONTROL
© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
Application of Certification tests for single station
Theoretical models-comparison for the whole sub-network (Mathematical checks for
simple cases)
Field trials
Cross check with other simulators
Initial operation feedback
Validation achievedValidation achieved
Other ACTS application areas Other ACTS application areas Other VDL modes (3,4)
1090 E.S.
UAT
3G systems
Satellites systems
……………………..
‘One Sky for Europe’
EUROCONTROL
© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
VDL Mode 2-ACTSVDL Mode 2-ACTS
‘One Sky for Europe’
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© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
ACARS Ground-Stations
ACARS applications in a Management Unit, CMU or ATSU
Analogic VHF radio or VDR running in ACARS mode
Current ACARS configuration
ACARS
applications
ACARS network
ACARS, VDL 2, AOA, ATN,ACARS, VDL 2, AOA, ATN, ...
ATN
New
CNS/ATM
applications
VDL 2Ground-Stations
Unchanged
ACARS
applications
AVLC
VDR running VDL mode2
CMU/ ATSU
D8PSK Tx/Rx
CSMA
AOA phase
VD
L 2
AOA data path
Unchanged
New CNS/ATM applications
ATN Router
8208
ATN phase
‘One Sky for Europe’
EUROCONTROL
© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
VDL2 Simulation Objectives
Accurate evaluation of capacity and performance of any VDL2 channel: Net Throughput Vs Channel load Collisions rate, retransmission rate Transmission delays
Identifying the critical aspects:
The impact of the “hidden and the exposed stations”
The ground-station density as providers currently plan
Critical capacity environment (airport or en-route domains...? )
Best frequency scenarios for current and future (2005-2010) air traffic demands both supporting ATS and AOC needs
‘One Sky for Europe’
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© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
Optimising the VDL Mode 2 MAC sub-layer (CSMA) and data-link layer (AVLC) parameters :
CSMA persistence (p) Different timers values (e.g M1, TM1, T1)
Evaluating the possible benefit of improvements to VDL Mode 2 standard: among others evaluating the impact of
Different p-values given to avionics (static or dynamic value), ground-
stations (en-route) and ground-stations (at airport). Hand-off mechanism (SQP scale, HO criteria)
VDL2 Simulation ObjectivesVDL2 Simulation Objectives
Giving input for future real time ATC simulations including data-link : To evaluate impact on operations of
Transmission delays Lost messages
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© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
Accurate Propagation delay (1m- precision)
VHF propagation model including large scale fading
D8PSK behaviour => BER calculation
Reed Solomon FEC-function, and related Frame error rate
VDL2 specific p-persistent CSMA Mac layer mechanism
Hidden/Exposed terminal effects
AVLC Data link layer aspects including hand-off
Dynamic Air traffic and tuneable Ground stations location
AOC and ATS Traffic Messages distribution in time
AOC and ATS message sizes distribution
ACTS VDL2 CapabilitiesACTS VDL2 Capabilities
• Standards:
• SARPS - VDL2 Technical Manual
• MOPS
• ARINC 618-5, 631-3
• MASPS RTCA/DO-224 A
‘One Sky for Europe’
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© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
Sept 02 High Level Simulation Requirements Oct/Nov 02 Architecture Jan 03 First Software release including VDL2 physical and MAC layer Feb 03 AVLC implementation March 03 First Simulation Inputs Scenarios definition March-December 03 Theoretical and cross check validation June 03 Discussion of initial results with AEEC, SITA and ARINC Nov 03 Definition of second set of simulations Jan- June 04 Presentation of results and contributions (in AEEC, ICAO WGM, with manufacturers, airlines, standard bodies…)
Main MilestonesMain Milestones
‘One Sky for Europe’
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© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
Technical aspectsTechnical aspectsACTS VDL Mode 2ACTS VDL Mode 2
‘One Sky for Europe’
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© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
Time samplingTime sampling
The simulator is not real time => Time has to be sampled.
However, the simulator is triggered on events
Time sampling frequency is critical for the simulation accuracy:
eg : with Fs = 300 MHz (period of 33 ns) => Position accuracy = 1m
‘One Sky for Europe’
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© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
Hidden and exposed terminalHidden and exposed terminal
GS 2GS 1
Hidden terminal can create collisions on the uplink
Exposed terminal can delay the downlink messages
Cases to be consideredRH AC1
RH GS1
Area to be studied
RH AC1
Interfering Area
GS1 and GS2 can not see each other, Aircraft sees both GS
‘One Sky for Europe’
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© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
VHF Propagation ModelsVHF Propagation Models
Free space propagation model commonly used by other simulators
Large scale fading (2 rays model vertical polarisation) which have been validated by STNA
Free SpaceLarge scale
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Receiving processReceiving process
Reception success rate can be derived from the transmitter/ receiver relative position
Propagationmodel
PReceived power
No ModulationScheme
BER
Tx and Rx filter loss
SNRprocess
Receiver
N0
Collided Frames power
SNR
Rx filter width
CorrectingCode
Frame length
FER Success/Failure
Random
RelativeTx/Rx
positions
Out of LOS ?
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Message collision processMessage collision processFor collision, worst cases are always considered:
Frames involved in collision are considered as additional WGN
=> BER and FER are then computed as previously with the specific noise level
10 15 20 25 30 35 40 45 5010
-5
10-4
10-3
10-2
10-1
100
SNR (dB)
SIR=10 dB
SIR=16 dB
SIR=17.5 dB
SIR=20 dB
SIR=30 dB
BER
‘One Sky for Europe’
EUROCONTROL
© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
List of system parametersList of system parameters Propagation model
Model in use ground type
Physical parameters Transmission power Antenna gain Cable lossVSWR Possibility to define range for these values Noise figure Filter widthChannel frequency
Mac sub-layer (CSMA) Station’s persistence TM1 : timer between two attempts M1 TM2
AVLC AVLC (VME, DLS) timers Number of retransmission Hands off algorithm
‘One Sky for Europe’
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© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
INPUTS Collection ProcessINPUTS Collection ProcessHigh- LevelHigh- Level
ECTL Analysis and
StatisticsLINK 2000+
ECTL CFMU
Flight DB
TrafficSimulator
Replay
ACTS
ARINC SITA
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Air Traffic inputAir Traffic input
Time ID Lat Long Alt Status04:40:18 TYR413D 47.8003 13.0192 1411 ON TAXI TO GATE04:40:18 TYR531L 47.9715 16.4778 3000 ON APPROACH04:40:18 TYR541G 48.0987 16.5806 586 ON TAXI TO GATE04:40:21 TYR413D 47.8005 13.0194 1411 ON TAXI TO GATE04:40:21 TYR531L 47.9725 16.4809 3000 ON APPROACH04:40:21 TYR541G 48.0985 16.5803 586 ON TAXI TO GATE04:40:24 TYR413D 47.8007 13.0196 1411 ON TAXI TO
The first step shall consist in using an Air traffic simulator log file.
The second step shall be to run an external library using CFMU flight plan as an input and able to give at any time any flight information. RAMS will provide such tool.
For more accurate simulations other information about aircraft behaviour, such as pitch, roll… could be integrated to achieve a more realistic link budget.
‘One Sky for Europe’
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© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
Formal co-operation with ARINC and SITA is setup to provide under NDA typical AOC traffic message profiles for airlines flying in Europe.
4 classes of airlines in terms of data-link usage:
Class 0 No data-link Class S Small Class M Medium Class L Large
Both deterministic and stochastic message distribution : The number of exchanged messages depends on :
The airline The flight phase (random distribution into the Flight Phase)
AOC Message profiles AOC Message profiles
‘One Sky for Europe’
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© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
4 classes of data-link users : Class 0 No data-link Class S Small Class M Medium Class L Large
Nr. Name Triggering event UL Msg
Nb DL Msg
Nb
1 Preflight at
gate 30 min. before take-
off 1 1 3 2 6 7
2 Taxi to dept.
runway Leaving dept. gate
(OUT) 1 1 1 1 1 2
3 Take-off Start from dept.
runway (OFF) 0 0 1 1 1 1
4 Departure 1 min. after take-off 0 0 1 0 1 1
5 En route Reaching TOC (top
of climb) 1 1 4 3 6 13
6 Approach Reaching TOD (top
of descend) 1 1 1 2 3 6
7 Landing Touch-down on dest.
runway (ON) 0 0 1 1 1 1
8 Taxi to dest.
gate Leaving dest. runway
1 1 1 1 1 2
9 Postflight at
gate Arriving at dest. gate
(IN) 2 2 3 3 5 6
AOC Messages profileAOC Messages profile
A message size distribution is also implemented for uplink and downlink, it depends on the airline class.
‘One Sky for Europe’
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ATS- Link 2000+ ApplicationsATS- Link 2000+ Applications
CM Application Service DLIC (Datalink initiation Capability)
CPDLC Application Service ACM (ATC communication management) ACL (ATC clearance) AMC (ATC Microphone check) DCL (Departure clearance) DSC (Downstream clearance)
DFIS Application Service D-ATIS
ADS Application Service FLIPCY (Flight plan consistency)
Transactions per flight 1 DLIC / FIR (ATSU) 1 FLIPCY / FIR (ATSU) 1 D-ATIS / Departure airport 1 D-ATIS / Departure TMA 1 D-ATIS / Arrival TMA 1 D-ATIS / Arrival airport 1 DCL / Departure airport 1 ACM / ATSU sector 5 ACL (3U,2D) / Departure TMA 16 ACL (1-2 per ATSU) in En-Route 10 ACL (6U,4D) / Arrival TMA 1DSC / En-Route 1 AMC / Sector
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Simulator Output (per station)Simulator Output (per station) Transmitter
Number of INF transmission request Number of INF transmitted % Re-transmission 0, 1, 2 …N2Average and maximum CSMA delay % of TM2 occurrence
Receiver Number of received INF Transmission delay (Average, maximum) (CSMA, propagation) in s Round trip delay in s % of msg out of delay (depending on the application) % of successfully acknowledged transmitted messages
Application related statistics: %CPDLC within allowed round trip delay % CAP within allowed one way delay
Others statistics: % of lost frames : % collision + % low SNR Hands off successes and failure Log on delay
‘One Sky for Europe’
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© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
Average and maximum uplink and downlink transmission delay
Average and maximum uplink, downlink round trip delay
Real channel load (for each GS point of view) (in % of time)
Net Throughput :with regards to INF0 frames (in kbits/s)
User data rate (without layers overhead) (in kbit/s)
Uplink and downlink success rate
Hands off success rate
Simulator Output (Simulator Output (common to all stationscommon to all stations))
‘One Sky for Europe’
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© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
2 main scenarios based on a critical sector : CDG-airport, Paris
The air traffic will be the peak hour of the peak day of 2002 (30 August)
2005 Single VDL 2 channel across Europe GS deployment as shown on map All AOC traffic assumed migrated to VDL2
2010 Stepwise, from 2 possibly up to 4 frequencies GS configuration as shown on map Increased AOC traffic, all ATS/Link2000 applications considered Aircraft equipment rate according to EUROCONTROL STATFOR inputs
ScenariosScenarios
‘One Sky for Europe’
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© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
Sita VDL2 Ground stations in 2005Sita VDL2 Ground stations in 2005
Area to be studied
Interfering area
‘One Sky for Europe’
EUROCONTROL
© 2002 European Organisation for the Safety of Air Navigation (EUROCONTROL)
For further information please contact :
Bertrand DESPERIER EEC / Brétigny CNS Tel +33 1 69 88 76 09Fax +33 1 69 88 78 [email protected]
Patrick DELHAISEEUROCONTROL DAS/CSMTel +32 2 729 34 78Fax +32 2 729 35 [email protected]