URICA Usageawa Re Interactive Content Adaptation for Mobile

URICA: Usage-awa. Re Interactive Content Adaptation for Mobile Devices Iqbal Mohomed, Jim Chengming Cai and Eyal de Lara Department of Computer Science University of Toronto Euro. Sys 2006: Session 10 – User Studies Wallach / de Lara

Heterogeneity in Mobile Devices • Significant Resource Variability among Mobile Devices • Screen real-estate • Networking • Battery Life • User Interface • Memory • Processing Capability

Need for Adaptation Downloaded Data 600 KB Network Connectivity Time (seconds) 1 Mbps (DSL) 5 3 G (384 Kbps) 12. 5 GPRS (40 Kbps) 120 Content must be customized!

Manual Adaptation • Publishers make available content for several classes of devices • e. g. , HTML and WAP versions of Web page • Disadvantages: High human cost • Done for every device (multiple versions) • Maintaining consistency and coherence • You can never cover all possible versions! • Continuous effort to support new types of devices • In practice: • Only done for few high-traffic sites • Limited number of devices • Slow update propagation • Not Scalable

Automatic Adaptation Mobile Device Adaptation Proxy Unmodified Content Server We Have The Mechanism But … The Hard Problem is Policies!

Achieving Fine Grain Adaptation • Usage affects the customization that is needed • Machines have a hard time distinguishing between good and bad adaptations • People are better

Achieving Fine Grain Adaptation • Usage affects the customization that is needed • Machines have a hard time distinguishing between good and bad adaptations • People are better • Users performing same task on content have similar adaptation requirements • Rely on a few users to adapt content for everyone

Usage-awa. Re Interactive Content Adaptation (URICA) • Allow users to interactively refine system’s adaptation decision • System learns from user modifications • Uses history for future adaptation predictions • Applicable to a wide range of adaptation types, such as image fidelity and page layout

How it Works 40 KB Server 1 Improve Fidelity Application Mobile 1 Adaptation Proxy Server 2 10 KB 20 KB Application Mobile 2 Prediction

Chameleon – a URICA prototype • Reduces bandwidth consumption and download latencies • Image Fidelity Adaptation System • Transcodes JPEG images on-the-fly to reduce file size • Uses history for prediction • Pocket Internet Explorer for Pocket. PC PDAs • Users can tap on images to improve fidelity

Adaptation Requirements Locality in user preferences Variation due to task and user preferences

Chameleon Prediction Policies • Minimizing bandwidth consumption or the number of user interactions required is trivial! • However, may not result in optimal latency

Chameleon Prediction Policies • Minimizing bandwidth consumption or the number of user interactions required is trivial! • However, may not result in optimal latency Start 2 3 4 Bandwidth Optimal 5

Chameleon Prediction Policies • Minimizing bandwidth consumption or the number of user interactions required is trivial! • However, may not result in optimal latency Download Time per Slice: 3 seconds User’s Average Interaction Time: 2 seconds User’s Desired Fidelity: 4 Start 2 3 4 5

Chameleon Prediction Policies • Minimizing bandwidth consumption or the number of user interactions required is trivial! • However, may not result in optimal latency Download Time per Slice: 3 seconds User’s Average Interaction Time: 2 seconds User’s Desired Fidelity: 4 Interaction Time Start 2 3 4 5 Download Time Fulfillment Time

Chameleon Prediction Policies • Minimizing bandwidth consumption or the number of user interactions required is trivial! • However, may not result in optimal latency Download Time per Slice: 3 seconds User’s Average Interaction Time: 2 seconds User’s Desired Fidelity: 4 Start 2 3 4 5 Interaction Time Download Time 0 6 Fulfillment Time

Chameleon Prediction Policies • Minimizing bandwidth consumption or the number of user interactions required is trivial! • However, may not result in optimal latency Download Time per Slice: 3 seconds User’s Average Interaction Time: 2 seconds User’s Desired Fidelity: 4 Start 2 3 4 5 Interaction Time Download Time 2 9 Fulfillment Time

Chameleon Prediction Policies • Minimizing bandwidth consumption or the number of user interactions required is trivial! • However, may not result in optimal latency Download Time per Slice: 3 seconds User’s Average Interaction Time: 2 seconds User’s Desired Fidelity: 4 Start 2 3 4 5 Interaction Time Download Time 4 12 Fulfillment Time

Chameleon Prediction Policies • Minimizing bandwidth consumption or the number of user interactions required is trivial! • However, may not result in optimal latency Download Time per Slice: 3 seconds User’s Average Interaction Time: 2 seconds User’s Desired Fidelity: 4 Start 2 3 4 5 Interaction Time Download Time Fulfillment Time 4 12 16

Personalized Adaptation Schedule • Optimizes expected fulfillment time • Time to reach fidelity level that satisfies user • Includes download and interaction time • Determines optimal personalized adaptation schedule • List of predictions • Schedule based on • Object adaptation history • Immediate bandwidth • User interaction time

PAS In Operation User’s Average Interaction Time: 2 seconds User’s Desired Fidelity: 4 Download Time per Slice: 3 seconds BW Start Optimal 2 3 4 5 Interaction Time Download Time Fulfillment Time 4 12 16

PAS In Operation User’s Average Interaction Time: 2 seconds User’s Desired Fidelity: 4 Download Time per Slice: 3 seconds BW Start Optimal 2 3 4 Start 3 4 5 PAS 5 Interaction Time Download Time Fulfillment Time 4 12 16 2 12 14

PAS In Operation User’s Average Interaction Time: 2 seconds User’s Desired Fidelity: 4 Download Time per Slice: 3 seconds BW Start Optimal 2 3 4 Start 3 4 5 PAS 5 Interaction Time Download Time Fulfillment Time 4 12 16 2 12 14 Download Time per Slice: 1 second PAS Start 5 0 5 5

User Study • 30 Participants • 3 Web sites • Word Recognition and Photo Album web site – all users doing the same task • Poster Ads web site – 3 groups, each with distinct task • PDA with CDMA 1 X Network Connectivity (66100 Kbps) • Prediction Mechanism was disabled • Chameleon initially served images at fidelity 1 • Users tapped on images to get next fidelity • Experiments performed on collected traces

Fulfillment Time Optimization – Single Task Adaptation can improve fulfillment time PAS has near-optimal performance

Fulfillment Time Optimization – Multiple Tasks Optimal behavior requires taking into account bandwidth and interaction time along with history

Fulfillment Time As Bandwidth Changes PAS is flexible Mean’s problems exacerbate

Additional Results in Paper • PAS can be used to achieve a desired tradeoff between bandwidth consumption and the number of required interactions • Users can specify a cost for having to interact with the system to correct the adaptation • Effect of User Interface on Adaptive Behavior of Users

Summary http: //adaptive. cs. toronto. edu/ Questions? • URICA is a general-purpose automatic content adaptation technique • Learns from user corrections to adaptation decisions • Chameleon is an image fidelity adaptation system that can be used to: • optimize fulfillment time • reduce bandwidth consumption • achieve user’s desired tradeoff between bandwidth consumption and the need to provide interactions