One Sky for Europe EUROCONTROL © 2002 European Organisation for the Safety of Air Navigation...

‘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]


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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


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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


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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


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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


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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


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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

……………………..


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VDL Mode 2-ACTSVDL Mode 2-ACTS


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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


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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


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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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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


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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


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Technical aspectsTechnical aspectsACTS VDL Mode 2ACTS VDL Mode 2


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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


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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


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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


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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


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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.


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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


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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.


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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


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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))


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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


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Sita VDL2 Ground stations in 2005Sita VDL2 Ground stations in 2005

Area to be studied

Interfering area


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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]

One Sky for Europe EUROCONTROL © 2002 European Organisation for the Safety of Air Navigation...

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Transcript of One Sky for Europe EUROCONTROL © 2002 European Organisation for the Safety of Air Navigation...