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Institute of Computer Science Department of Distributed Systems Prof. Dr.-Ing. P. Tran-Gia QoEWeb: Quality of Experience and User Behaviour Modelling for Web Traffic Tobias Hoßfeld hossfeld@informatik.uni-wuerzburg.de
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2 Tobias Hoßfeld hossfeld@informatik.uni-wuerzburg.de Partner University of Würzburg Tobias Hoßfeld, Daniel Schlosser, Thomas Zinner, Valentin Burger Blekinge Institute of Technology Markus Fiedler, Patrik Arlos, Junaid Shaikh France Telecom SA Sergio Beker, Denis Collange, Frédéric Guyard, Frédérique Millo Warsaw University of Technology Zbigniew Kotulski, Wojciech Mazurczyk, Tomasz Ciszkowski http://www3.informatik.uni-wuerzburg.de/research/projects/qoeweb/
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3 Tobias Hoßfeld hossfeld@informatik.uni-wuerzburg.de Motivation User behavior strongly influences systems e.g. selfishness, churn, or pollution in P2P systems time-based or volume-based models in shared systems But, current web traffic models do not consider QoE / user behavior / impatience ! Derive QoE and user behavior model for web traffic based on active measurements in a laboratory test passive measurements within an operator’s network Apply model and evaluate its impact on selected examples wireless networks with shared capacity reputation management to react before the user reacts
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4 Tobias Hoßfeld hossfeld@informatik.uni-wuerzburg.de Agenda Impact of User Behavior Example: rate control in UMTS Active and passive measurements QoE and User Behaviour Modelling for Web Traffic non-linear interdependency between QoE and QoS timely behavior Reputation Management Work plan
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5 Tobias Hoßfeld hossfeld@informatik.uni-wuerzburg.de Example: Rate Control in UMTS Systems Best-effort user and QoS user with guaranteed bandwidth Time- and volume-based user: e.g. voice calls and FTP user Impact of user behavior on performance of system? Transmission Power for QoS user? Rate for BE user! BS x Time Transmission Power for QoS1 QoS1 QoS2 QoS4 QoS3 BE3 BE1 BE2 Transmission Power for BE3 Constant Transmission Power for DPCCH
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6 Tobias Hoßfeld hossfeld@informatik.uni-wuerzburg.de A Priori Source Traffic Model of a Web User Viewing Time V Web Page WWW Session InterSessionTime I Inline Object GetReq. TCP 1 TCP 2 TCP 3 TCP 4 GetReq. Inline Object Inline Object GetReq.Inline Object Inline Object GetReq. Inline Object Main Object GetReq. Web Page Number X of Web Pages GetReq. Volume R of GetRequest Volume M of Main Object Volume O of Inline Object Number N of Inline Objects N
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7 Tobias Hoßfeld hossfeld@informatik.uni-wuerzburg.de Simulation: Web Users in Rate-Controlled UMTS Different conclusions according to user behaviour model volume-based users: rate control degenerates?! time-based users: rate control works as expected?! Important to get realistic models volume-based userstime-based users web users rate decreases duration of session increases number of users increases
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8 Tobias Hoßfeld hossfeld@informatik.uni-wuerzburg.de Basic Queueing Theory Birth-Death-Model Time-based users Volume-based users 0 µ0µ0 1 λλ µ1µ1 M(1)-1M(1)M(1)+1 λλλλ µ M(1)-1 µ M(1) µ M(1)+1 µ M(1)+2 n-1n λλ µ n-1 µnµn Basic queueing theory leads to same qualitative results understanding of system behavior will be applied in QoEWeb
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9 Tobias Hoßfeld hossfeld@informatik.uni-wuerzburg.de Agenda Impact of User Behavior Example: rate control in UMTS Active and passive measurements QoE and User Behaviour Modelling for Web Traffic non-linear interdependency between QoE and QoS timely behavior Reputation Management Work plan
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10 Tobias Hoßfeld hossfeld@informatik.uni-wuerzburg.de Objectives of Measurements Active measurements quantification of user impatience due to bad network conditions quantification of the decrease of satisfaction as a function of time or actions disturb QoS in laboratory environment user survey can also be applied to interpret passive measurements Passive measurements investigate the statistical behavior of web traffic analyze the correlations between the behavior of users and some network performance metrics
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11 Tobias Hoßfeld hossfeld@informatik.uni-wuerzburg.de Passive Measurements: Traffic Modeling Daily behavior Typical hours Model of web transfers / sessions Traffic metrics: up/down volume, type of end Network performance criteria: throughput, loss rate, RTT Application level performance: response time, cancelled downloads Type of web transfers with similar characteristics Aggregation in sessions (threshold ?) Type of web servers Influence of the hourly variations Model the behavior of web users, typology
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12 Tobias Hoßfeld hossfeld@informatik.uni-wuerzburg.de Analysis of Correlations Correlation between traffic metrics and performance criteria For web transfers / sessions / users significant performance criteria, dependence function according to the type of transfer / session the type of users
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13 Tobias Hoßfeld hossfeld@informatik.uni-wuerzburg.de Agenda Impact of User Behavior Example: rate control in UMTS Active and passive measurements QoE and User Behaviour Modelling for Web Traffic non-linear interdependency between QoE and QoS timely behavior Reputation Management Work plan
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14 Tobias Hoßfeld hossfeld@informatik.uni-wuerzburg.de Interdependency between QoE and QoS Comparing iLBC and G.711 voice codecs Similar results for both codecs regarding packet loss IQX (exponential interdepency) cannot be rejected iLBCG.711
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15 Tobias Hoßfeld hossfeld@informatik.uni-wuerzburg.de Impact of Autocorrelated Delays For different correlation factors, still exponential relationship valid Clear impact of correlation, i.e. timely dependencies, on QoE
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16 Tobias Hoßfeld hossfeld@informatik.uni-wuerzburg.de Combining Active and Passive Measurements Viewing Time V Web Page WWW Session InterSessionTime I Inline Object GetReq. TCP 1 TCP 2 TCP 3 TCP 4 GetReq. Inline Object Inline Object GetReq.Inline Object Inline Object GetReq. Inline Object Main Object GetReq. Web Page Number X of Web Pages GetReq. Volume R of GetRequest Volume M of Main Object Volume O of Inline Object Number N of Inline Objects N User will abort if QoE is too bad or enjoy browsing and prolongs sessions for good QoE Content and usage of web is changing download of documents: pdf, ppt, … video streams services like chat or RDP Web page may not only be provided by a single server, but from a CDN from different service providers (Akamai, ads server, …)
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17 Tobias Hoßfeld hossfeld@informatik.uni-wuerzburg.de Agenda Impact of User Behavior Example: rate control in UMTS Active and passive measurements QoE and User Behaviour Modelling for Web Traffic non-linear interdependency between QoE and QoS timely behavior Reputation Management Work plan
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18 Tobias Hoßfeld hossfeld@informatik.uni-wuerzburg.de Reputation concept Reputation is a proven mechanism for reflecting aggregated level of trust to network services, users, shared resources (e.g. auctioning systems, P2P networks, distributed wireless networks such as MANET; eBay, eDonkey, SecMon) Reputation management is a feedback decision process being in charge of examining the given reputation (e.g. QoE, service performance) and triggering/enforcing remedy procedures on the on-line or threshold basis Key features of reputation present and historical measurements are weighted and reflect an its evolution and dynamics in distributed P2P environments reputation is shared among network nodes reinforcing decision process based on historical measurements estimates future expectations
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19 Tobias Hoßfeld hossfeld@informatik.uni-wuerzburg.de Reputation application in QoEWeb Reputation building For a particular Web service/Web traffic a perceived level of user satisfaction ST is expressed by QoE metrics and quantified according to the created model of user behaviour Own experience OE of reputation is fed by ST, applying historical data shaping with WMA function For shared reputation V service reputation SR is created with respect to credibility of recommenders IR Reputation usage in QoEWeb Evaluation of QoE metrics dynamic with respect to a particular Web services (web surfing, high throughput data, live streaming, interactive real time communication, etc) Detects deterioration of networks performance before the user perceived QoE goes down below a critical level
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20 Tobias Hoßfeld hossfeld@informatik.uni-wuerzburg.de Agenda Impact of User Behavior Example: rate control in UMTS Active and passive measurements QoE and User Behaviour Modelling for Web Traffic non-linear interdependency between QoE and QoS timely behavior Reputation Management Work plan
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21 Tobias Hoßfeld hossfeld@informatik.uni-wuerzburg.de Work Plan
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