Joachim Pomy Consultantjoachimpomyde OPTICOM Germany ITU Workshop on Performance Quality of Service and Quality of Experience of Emerging Networks and Services Athens Greece 78 September 2015 ID: 780145
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Quality of Service (QoS), Quality of Experience (QoE) and Performance
Joachim PomyConsultant@joachimpomy.deOPTICOM, Germany
ITU Workshop on “Performance, Quality of Service and Quality of Experience ofEmerging Networks and Services”(Athens, Greece 7-8 September 2015)
Slide2Where it All Begins:Real Communication Situation
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Slide3... and where End-to-End Quality comes to Play:
Employing a Telecommunication System3
... can you hear me ?
... I want to speak now !
Slide4Definitions start here: ITU-T Rec. E.800
Quality of Service
Service Support PerformanceService Operability PerformanceServeabilityService Security Performance
4Network PerformanceCharging PerformanceProvisioning PerformanceAdministration PerformanceAvailability PerformanceTransmission Performance
Network Performance (NP)Pre-requisite to Quality of Service (QoS)Not directly visible to the userQuality of Service (QoS)Performance of the Service offered to the UserSome QoS Aspects directly perceivable, some indirectly
Slide5Four Viewpoints of QoS
Consistent Approach to QoSWell-defined and Relevant (e.g. Customer-affecting)
Used to Plan and Deploy NetworksIncludes Monitoring Service Quality ITU-T Rec. G.1000 defines four Viewpoints of QoSCustomer's QoS RrequirementsService provider's offerings of QoS (or targeted QoS)QoS achieved or deliveredCustomer survey ratings of QoSIdeally there would be 1:1 Correspondence between Delivered QoS and Perceived QoS
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Slide64 Viewpoints of QoS
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Slide7ITU-T Rec. G.101
The Transmission Plan
Fundamental principles of transmission planningA good transmission plan is set up in order to deliver to users signals that are at a desirable level and free from objectionable amounts of delay, echo and distortion Has to take into account transmission parameters and impairments, different network configurations and elements Specific transmission plans have to be set up in order to take care of specific transmission impairments and conditions fortraditional narrow-band telephone networks
mobile networkspacket switched networksmultimedia applications 7
Slide8Traditional Transmission Planning
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Slide9Transmission Planning Today
ITU-T Rec. G.108: Transmission Planning with the E-ModelTraditional transmission planning methodologies no longer flexible enough to account for new factors
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Slide10Transmission Planning Challenges - 1
Multinational networks require planning which takes into account regional differences in loss plan requirements and inter-network transmission plans
Due to liberalization of the telecommunication markets (e.g. in Europe) there are no longer laid down ranges of values for transmission parameters by regulationThe changing scenario in the public network operator domain is impacting transmission performance10
Slide11Transmission Planning Challenges - 2
G.108 is applicable to the use of new technology within the networks, including wireless (cordless or mobile), IP transmission etc.
G.108 provides planning methods and contains necessary information and tools which will enable the planner to design the network transmission plan Guidelines and planning examples are based on the use of the E-Model11
Slide12E-Model - ITU-T Rec. G.107
Computational model for use in transmission planning Assessing the combined effects of variations in several transmission parameters that affect conversational quality of 3.1 kHz handset telephony
Covers also packet lossFor many combinations of high importance to transmission planners, the E-model can be used with confidenceCaution must be exercised when using the E-model for some conditions 12
Slide13Reference connection of the E-model
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Slide14Effects of Talker Echo in the Presence of Delay
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50
60
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90
100
0
50
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Mouth-to-Ear-Delay / ms
E-Model Rating R
no Talker Echo
TELR=65 dB
TELR=55 dB
TELR=45 dB
TELR=35 dB
TELR=25 dB
Slide15Categories of Communication Quality
in Terms of Users' Satisfaction Classes
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Voice Quality Continuum
Slide16Example with Delay as Impairment
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Slide17QoE Definition
ITU-T Rec. G.100 / P.10 definesQuality of Experience (QoE): The overall acceptability of an application or service, as perceived subjectively by the end-user.
NOTE 1 – Quality of experience includes the complete end-to-end system effects (client, terminal, network, services infrastructure, etc.).NOTE 2 – Overall acceptability may be influenced by user expectations and context.17
under review !
Slide18QoE Implications
QoE includes „everything“Many aspects out of control of OperatorsIncludes Terminal Aspects
Conext and Environment of the UserProper QoS and NPTechnical pre-requisitesFor achieving desired QoE 18
Slide19Users‘
Perception of Speech Quality
19Speech(Transmission) Quality
...
...
Sound Quality &
Naturalness
Intellegibility
Listening & Talking
Efforts
Conversational
Efforts
Doubletalk
Capability
Expectation
Backgroundnoise
Transmission
Speech
Charakteristic
Individual
Perception
Network
Conditions
Environmental
Conditions
Slide20Motivation for Multimedia Quality - 1
Quality as perceived by the User A Promotional Factor for the Market
User compares Quality of New Telecommunication ServicesWith Quality experienced in the PastWith other Telecommunication Service offersWith Quality experienced for Entertainment Services 20
Slide21Motivation for Multimedia Quality
Individual Quality ThresholdUsers try new Service only few times ( ~ 3x … 5x )If Quality below Indivdual Threshold Users give up
e.g. Download of a Website takes too long User remembers this experienceWill try a few times and conclude this as Static Effect:"This website is not useable - let's try the Offer of the Competitor…" 21
Slide22Diffusion, Transmission Qualityand Expectation for an Innovation
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Diffusion Theory generally accepted for describing Consumer Behaviour on the Introduction of an Innovation or New ServiceNumber of Users develops in S‑shaped Curve5 Classes of Users:(1) Innovators(2) Early Adaptors(3) Early Majority(4) Late Majority(5) LaggardsTrade-off between Transmission Quality and New Functionality
Slide23Changes in Users' Behaviour - 1
Users tend to be much more reluctant to accept lower qualityThis is quoted frequently
True for some sorts of social callsDefinitively NOT true for sensible business callsDoes it help network operators when defining QoS for their network ?High quality has to be provided when demanded by business customers or other sensible clientsBut the distribution of quality acceptance over time and areas cannot be matched with the occurrence of impairments in the networkNot really useful for designing networks
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Slide24Changes in Users' Behaviour - 2
Users switch between different communication devicesWireline, wireless, PC, PDA etcDepending on place, task, purpose
And depending on QUALITY24
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Slide25Key Parameters affecting MM Quality
Media Distortion End-to-End Delay
Echo Effects Information Loss Background Noise Distortion Loss of Synchronization between Media Streams25
Slide26Example: Lip Sync
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Slide27Impairments in packet networks
Distinction between Effects
that occur in the Network andMechanisms in the Terminals that are affected Terminals can be used to correct for the Effects in the Network Remaining Issues are:End-to-End Delay is increased when compensating for other EffectsLoss of Information can be Concealed but Not Recovered
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Slide28Impairments in packet networks
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Slide29QoS Layers in Mobile
QoS model for mobile has four layers.
First layer is the Network Availabilitydefines QoS rather from the viewpoint of the service provider than the service userSecond layer is the Network Accessfrom user's point of view basic requirement for all the other QoS aspects and parametersThird layer contains other QoS aspectsService Access, Service Integrity & Service Retainability
Different services are located in the fourth layerTheir outcome are the QoS parameters as perceived by the user29
Slide30QoS aspects of Mobile
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Slide31POLQA™ - Rec. P.863
The limitations of existing standards that are now addressed by
POLQACDMAChinese 3G TD-SCDMAPOLQA offers immediate, strong support for testing of new wideband 4G/LTE networks delivering HD-quality voice services
Tests carried out during the POLQA evaluation included future technologies such asUnified CommunicationsNext Gen Networks4G/LTEHD Voice, i.e. "wide-band" and "super-wide-band" See POLQA: The Next Generation in Voice Quality Testing http://www.polqa.info31
Slide3232
Slide3333
POLQA Introduction - (c) OPTICOM GmbH 2010
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Performance Validation
The ITU has validated POLQA on:
Languages included in the POLQA validation:
German
Swiss German
Italian
,
Japanese
,
Swedish
American English and British English
Chinese (Mandarin),
Czech,
Dutch,
French,
47000
file
pairs
across
64
subjective
experiments
Slide34Confidence
Intervalls for Different Sample Sizes (1)
Effect of different sample sizes in a measurement campaignbased on the Pearson-Clopper formulas for calculation of confidence intervalsvalid in a generic way and even for small sample sizesfor higher sample numbers, the calculation of confidence intervals based on the approximation of a normal distribution can be applied
Three different graphs are depicted: Sample sizes in the range:between 100 and 1 100 samples;between 1 100 and 2 100 samples; andbetween 1 000 and 11 000 samples.34
Slide35Confidence
Intervalls for Different Sample Sizes (2)
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Slide36Confidence
Intervalls for Different Sample Sizes (3)
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Slide37Confidence
Intervalls for Different Sample Sizes (4)
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Slide38KPIs based on Network Counters
Vendor specific = network internal KPIs
different strategieshow to count network eventswhich events are included in which counter(s)Requires knowledge of specific systemspecialists with detailed system knowledgetesting the countersdocumentation may be faulty
approach to counter change with system updateMobile operators struggling with thismost operator live in a multi vendor environmentcounters from different vendors cannot be directly comparedrequires continous attention and a strategy38
Slide39KPIs from Users' Perspective = KQIs
Key Quality Indicators (KQIs) = external indicatorscan be assessed in the FieldFor Monitoring, Regulation etc.
a subset can be selectedapplicable across all vendors & operatorsnot limited to mobile, but also good for broadband 39
Slide40KPIs versus KQIs
Sometimes confused
KPIs = internal indicatorspart of network performancebased on network countersessential for operation, maintenance, business modelcould be reported, audited etc.however, meaningless when out of contextKQIs
= external indicatorsbasis for QoS assessment as perceived by the uservendor independantoperator independantideal to compare different operators on a statistical basiscannot be reported from the system itselfrequires some kind of field testing, drive, walk etc.40
Slide41Any questions ?
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Contact:
Consultant@joachimpomy.de