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UIC ERTMS World Conference. GSM-R Quality Performance Tools … and how to use it for ETCS L2. Why is Quality of Service important ?. Tools are needed to prove QoS. 2. GSM-R is essential for train operations QoS is important to support safe and on time train operations
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UIC ERTMS World Conference GSM-R Quality Performance Tools …andhowtouseitfor ETCS L2
Whyis Quality of Service important? Tools areneededtoproveQoS 2 • GSM-Ris essential fortrainoperations • QoSisimportanttosupportsafe and on time trainoperations • Restrictionshaveinfluenceon delayminutes • Frequentdisruptionscauseunintended actionsbyuserswhichleadtounsafe conditions
Stakeholder • Who else is interested in a high QoS? 3 QoS is not only relevant for GSM-R network operators to fulfil requirements and expectations of users and to avoid rail service disruptions. • Train operating companies, to provide good service to passengers • Rail infrastructure managers, to avoid unsafe conditions and penalties for delay minutes • National authorities and Notified Bodies, to approve and certify the GSM-R network according to technical specifications for interoperability
MeasurestoensureQoS WhatarethebasicactivitiestoensuretheneededQoS? 4 • DetailedQoSmeasurementsbeforestartofoperation • Repetitive measurements (at least once a year) • includingpublicnetworks • Usageof Performance Monitoring Tools • Analysis ofdataprovidedby GSM-R managementtools (e.g. fault history, errorstatistics) • Monitoring of KPI development • Considerationof additional informationprovidedby: • Connected Systems (Onboardequipment, RBC) • Users • Externalsupporttoverifyexistingdata
QoS – importantrequirements 5 Importantrequirementsregarding all activitiestoensureQoSare: • completeness • traceability • automatisation • acceptance …definitionofstandardizedtestcases is vital! …andit must beclearwhatthe impact on trainoperationsis, if a KPI cannotbefulfilled!
Call Performance Monitoring Reports • Radio Module: RxLev, RxQual, Timing Advance,… • ISDN Module: terminated and originated PtP Calls, VGCS,… • Euroradio Module: ETCS and GSM-R features • Roaming Module: inbound / outbound roaming,… • GPRS Module: data application QoS analyses • List of worst cells • Most frequent end causes • Failure distribution per mobile
Black Box Measurement System Data GSM-R Black Box installed in engines Collected Data • A hugeamountofdatacomingfromseveralblack box systemsprovidingstatistical relevant analysis • trendofquality / performance
GSM-R measurementsystem in roadbedandtrackmeasurementwaggon Performance dataexactlycorrelatedtotrackchainage Database GSM-R submeasurementsystem (FME) DB Query Eachtrackonce a year High prioupto 6 times a year
Activevs. Passive Probes Active Probes / Test system Based on the generation of artificial traffic Passive Probes Based on data extraction from network elements Pro’s • Allows to monitor all the transactions • Massive quantity of data ensures statistical relevancy • Allows to perform the type of test wich is of interest, when and where it is required/necessery Limitations • It’s just a snapshot picture of the network • Not statistically relevant • Data available only if there are transactions: no calls no data…. • Not possible to perform the test required when and where needed.
Traffic model vs. Monitoring recommendations Traffic Model Monitoring recommendations Historic lines with GSM-R train radio. No ETCS Level 2. • Human generated traffic • Voice calls • Low traffic volume • Active Probes are a must-have • Passive Probes suggested • OMC-R counters for monitoring High speed lines with ETCS Level 2 in operation. • OBU traffic • Long continous data connections • High availability requirements • Passive Probes are a must have • Active Probes needed for periodic data testing QoS according to UIC standard O-2475
Usecase: QoSmeasurementsfor ETCS L2 in Austria 11 • ForthenewbuiltlinesQoSmeasurementsweredonefor a speedupto 330km/h • The measurementsaredonewithin different campaigns • After everymeasurementcampaignthesystemshavetobeoptimized! • Forstatistical valid resultsmeasurementsareperformedseveraltimesforeverytrack! • ~ 16 days per track • ~ 120 testruns in total per track • morethan 200 hoursofmeasurementsper track
QoS Measurement System Mobiles from different supplierswereusedwhichareinstalled in thecab. Based on theshowntestequipment, itispossibletogetinformationaboutthebehaviourof different onboardequipment.
Key Performance Indicator • Summary ofmeasurementresultsofbothmeasuringdaysandbothmeasurementsystems: • Connection Loss Rate (seeexamplebelow) • HandoverSuccessRate (seeexamplebelow) • Network Registration Delay • Transfer Delay • Error Free Period • etc. 14
Conclusions 15 • The Austrian experience is that continuous QoS activities should be done with internal resources in order to take into account railway specific conditions • Nevertheless it is necessary to define for which activities external support is necessary (SLA contracts, detailed evaluations, etc.) • Try to combine QoS measurements with other activities such as track inspection • This allows to reduce efforts and to combine different information (e.g. GPS coordinates and track position) • Results have to be taken into account in further planning processes • Information exchange between network operations and planning department • It is important to identify critical areas and to focus on that • QoS ensuring is an ongoing process, therefore we are still working to improve the applied methods!
Questions? Thank you for your attention! 16
