USER-ACTIVITY AWARE STRATEGIES FOR MOBILE INFORMATION ACCESS A Thesis Presented to The Academic Faculty by Tae-Young Chang In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the School of Electrical and Computer Engineering Georgia Institute of Technology April 2008 USER-ACTIVITY AWARE STRATEGIES FOR MOBILE INFORMATION ACCESS Approved by: Professor Raghupathy Sivakumar, Professor Magnus Egerstedt Advisor School of Electrical and Computer School of Electrical and Computer Engineering Engineering Georgia Institute of Technology Georgia Institute of Technology Professor George Riley Professor Umakishore Ramachandran School of Electrical and Computer College of Computing Engineering Georgia Institute of Technology Georgia Institute of Technology Professor Chuanyi Ji Date Approved: January 9, 2008 School of Electrical and Computer Engineering Georgia Institute of Technology To my family iii ACKNOWLEDGEMENTS I would like to acknowledge many people for helping me during my doctoral work. First of all, I would like to extend my sincere gratitude and appreciation to my advisor, Professor Raghupathy Sivakumar, for his assistance, advice, and support during my study. Throughout my doctoral work, he encouraged me to develop independent thinking and research skills. He continually stimulated my analytical thinking and greatly assisted me with scientific writing. I would like to thank Prof. George Riley and Prof. Chuanyi Ji for serving on my proposal and dissertation committees. I also thank Prof. Magnus Egerstedt and Prof. Umakishore Ramachandran for serving on the dissertation committee. They gave valuable opinions during the preparation and presentation of this dissertation, and I am deeply thankful to them. I thank the present and past members of the GNAN research group for their warm advice and support. Special thanks to Aravind, Zhenyun, Karthik and Kyu-Han for their collaboration in my research. My thanks also go out to Ashraf, Hung-Yun, Seung-Jong, Ram, Yujie for their friendship and assistance. Sandeep, Sriram, and Cheng-Lin shared their constructive comments on my research, and I wish to thank them. I thank Dr. Yeonsik Jeong for his valuable advice. My very special thanks to my parents and sisters. Their unwavering faith and confidence in my abilities is what has shaped me to be the person I am today. Finally, I woud like to thank my wife, Yejin, and my daughter, Katherine Yuna for their loving support, encouragement, and sacrifice during my study. iv TABLE OF CONTENTS DEDICATION ....................................... iii ACKNOWLEDGEMENTS ................................ iv LISTOFTABLES .................................... ix LISTOFFIGURES .................................... x SUMMARY......................................... xii I INTRODUCTION.................................. 1 II MOTIVATIONANDRELATEDWORKS . 4 2.1 ProblemSetting ................................ 4 2.2 Challenges ................................... 5 2.2.1 Greedy Content Fetching . 5 2.2.2 Non-Linearity in Size between User-Activity and File Update . 6 2.3 RelatedWorks ................................. 6 2.3.1 MobileFileSystems .......................... 6 2.3.2 Thin-ClientComputing . 8 2.3.3 WebCharacteristics .......................... 9 2.3.4 WebCaching.............................. 9 2.3.5 Prefetching............................... 11 2.3.6 Transcoding .............................. 12 III CONTRIBUTIONSANDOVERVIEW . 15 IV APPLICATION-UNAWARE READ ACCESS FOR NON-PARTITIONABLECONTENT . 19 4.1 Introduction .................................. 19 4.2 Motivation ................................... 20 4.2.1 Not all content is always seen by users . 21 4.2.2 Users suffer when response times are large . 23 4.2.3 Larger file transmissions suffer from frequent disconnections . 24 4.2.4 Greedy transmission makes network utilization inefficient . 25 4.3 Application-unaware content partitioning . ........ 26 v 4.3.1 Graphical-domain content partitioning . 26 4.3.2 Thin-clientcomputing. 29 4.4 Cut-LoadArchitecture. 35 4.4.1 Dynamic Mode Selection . 36 4.4.2 OpportunisticHoarding. 40 4.4.3 ModeTransfer ............................. 43 4.4.4 Integrated Operation . 44 4.5 PerformanceEvaluation . 44 4.5.1 SimulationSetup............................ 44 4.5.2 Impact of thin-screen data size . 46 4.5.3 Impact of network characteristics . 48 4.5.4 Impactofweight............................ 51 4.5.5 PrototypeStrawman ......................... 52 4.6 Summary.................................... 54 V APPLICATION-AWARE READ ACCESS FOR PARTITIONABLECONTENT . .. .. .. .. .. .. .. 55 5.1 Introduction .................................. 55 5.2 Motivation ................................... 56 5.2.1 Web Access Model and Simulation Setup . 56 5.2.2 Screen Contention Problem . 59 5.2.3 Bandwidth Underutilization Problem . 62 5.2.4 Summary................................ 64 5.3 OverviewofSolution.............................. 64 5.4 ObjectPrioritization(OP) . 66 5.4.1 Initial Object Prioritization . 67 5.4.2 Selective Object Fetching . 68 5.4.3 Re-prioritization ............................ 68 5.4.4 AnalyticalModel ........................... 69 5.5 ObjectsReordering(OR) . 69 5.5.1 InitialObjectsAssignment . 69 5.5.2 DynamicObjectsRescheduling. 70 vi 5.5.3 TCP-awareObjectsReordering . 71 5.5.4 AnalyticalModel ........................... 72 5.6 Connection Management (CM) . 73 5.6.1 Per-Connection Load Estimation . 73 5.6.2 Dynamic Connection Assignment . 73 5.6.3 AnalyticalModel ........................... 74 5.7 SimulationResults............................... 75 5.7.1 SimulationSetup............................ 75 5.7.2 Impact of Object Characteristics . 76 5.7.3 Impact of Number of Connections and Servers . 77 5.7.4 Impact of Network Characteristics . 77 5.7.5 ImpactofFastScroll ......................... 78 5.8 PrototypeImplementation . 79 5.8.1 Background: Architectural Overview of Web Browser . ..... 79 5.8.2 PrototypeDesign ........................... 81 5.8.3 PerformanceResults. .. .. .. .. .. .. .. 82 5.9 Summary.................................... 84 VI USER-ACTIVITY SHIPPING FOR FILE SYNCHRONIZATION . 86 6.1 Introduction .................................. 86 6.2 Motivation ................................... 87 6.3 ArchitectureofMimic . .. .. .. .. .. .. .. .. 90 6.3.1 OverviewofMimic........................... 90 6.3.2 Message Optimization . 92 6.3.3 Integration with File System . 95 6.4 ClientOperationsinMimic . 97 6.4.1 Decision of Mimic Operation . 97 6.4.2 AR Header Generation . 98 6.4.3 MessageCapture............................ 99 6.4.4 Termination .............................. 100 6.4.5 Bookkeeping .............................. 101 6.5 ServerOperationsinMimic. 102 vii 6.5.1 Decision of Playback Operation . 102 6.5.2 Initialization .............................. 102 6.5.3 ActivityPlayback .. .. .. .. .. .. .. .. 103 6.5.4 File Verification . 104 6.6 PerformanceEvaluation . 105 6.6.1 PrototypeDescription. 105 6.6.2 ExperimentalSetup . 108 6.6.3 TransferSizePerformance . 109 6.6.4 LatencyPerformance . 115 6.6.5 SystemOverheads .. .. .. .. .. .. .. .. 117 6.6.6 User statistics and expected results . 117 6.7 Summary.................................... 120 VII CONCLUSIONS................................... 121 REFERENCES....................................... 123 VITA ............................................ 131 viii LIST OF TABLES 1 An example of content classification. 38 2 Web statistics of Top 50 Web Sites. 58 3 Comparison between diff andactivitysize.. 89 4 Application index for experiments. 106 5 User activity index for experiments. 107 6 Statistics of insertion, modification, and deletion in the test. 118 7 Expected transfer-size reductions from insertion, modification, and deletion. 118 8 Frequency of copying and meta-data change in the test. ....... 119 9 Expected transfer-size reductions from copy-and-paste and meta-data change. 119 ix LIST OF FIGURES 1 TransfersizeinHTML. ............................. 22 2 TransfersizeinAcrobat............................. 22 3 TransfersizeinWord. .............................. 22 4 ResponsetimeinHTML. ............................ 22 5 ResponsetimeinAcrobat............................. 22 6 ResponsetimeinWord. ............................. 22 7 Bandwidthwastage. ............................... 25 8 Time-outrate. .................................. 26 9 Thin-clientcomputingmodel. 29 10 TransfersizeinWLAN. ............................. 31 11 ResponsetimeinWLAN. ............................ 32 12 ResponsetimeinWWAN............................. 32 13 Average transfer size for 10 sample pictures. ........ 33 14 Transfer size of localized computing. ...... 33 15 Cut-Load architecture overview. 35 16 Transmissioninthickmode.. 41 17 Transmissionindualmode. 41 18 Pseudo code for the integrated operation. ...... 45 19 PDF of document and thin-screen data size. ..... 47 20 Per-screenresponsetimeinCut-Load. ..... 47 21 CumulativeresponsetimeinCut-Load. 49 22 ImpactofbandwidthinCut-Load . 50 23 ImpactofframelossrateinCut-Load . 50 24 ImpactofweightinCut-Load . 51 25 Cut-Loadprototype. ............................... 52 26 Experimental results of Cut-Load prototype. ....... 53 27 Typical network topology for Web access. ..... 57 28 Object fetching sequence at amazon.com. ................... 60 29 Fetching with screen contention in a conventional Web browser........ 60 x 30 Fetching without screen contention in an ideal Web browser. ........ 61 31 Impactofscreencontention.. 61 32 Fetching with synchronized ending time in ideal