The Influence of Delay on Cloud Gaming Quality of Experience (T-Labs Series in Telecommunication Services)

This book provides an understanding of the impact of delay on cloud gaming Quality of Experience (QoE) and proposes techniques to compensate for this impact, leading to a better gaming experience when there are network delays. The author studies why some games in the cloud are more delay sensitive than others by identifying game characteristics influencing a user's delay perception and predicting the gaming QoE degraded by the delay. The author also investigates the impact of jitter and serial-position effects on gaming QoE and delay. Using the insight gained, the author presents delay compensation techniques that can mitigate the negative influence of delay on gaming QoE that use the game characteristics to adapt the games. Preface 7 Acknowledgments 9 Contents 10 About the Author 13 Acronyms 14 1 Introduction 17 1.1 Motivation 17 1.2 Research Question and Scope 19 1.3 Structure of the Book 21 2 Gaming QoE Assessment 22 2.1 Introduction 22 2.2 Cloud Gaming 23 2.3 Concept of QoE 25 2.4 Gaming Taxonomy 26 2.5 Gaming QoE Influencing Factors 28 2.5.1 Human Factors 28 2.5.2 Context Factors 29 2.5.3 System Factors 29 Media-Related System Influencing Factors 30 Playing Devices 30 Network 31 Game 32 2.6 Quality Features 33 2.6.1 Game-Related Aspects 33 Interaction Quality 33 Playing Quality 34 Appeal 34 2.6.2 Player Experience Aspects 34 2.7 Methods for Assessing Gaming QoE 35 2.7.1 Questionnaire 38 2.7.2 Experimental Setup of Laboratory Environment 41 2.7.3 Experimenting Using Crowdsourcing Platform 41 Rating Platform 42 Crowd Gaming Framework 43 2.8 Summary 45 3 Influence of Delay on Gaming QoE 46 3.1 Introduction 46 3.2 Interactive Dataset of ITU-T Rec. G.1072 47 3.2.1 Data Analyses 49 3.3 Game Characteristics Influencing Delay Sensitivity of Games 51 3.3.1 Focus Group Study (Study 3.1) 52 Demographics of Participants 53 Experiment Details 53 Identified Characteristics 53 3.3.2 Definition and Categorization of the Characteristics 54 Temporal Accuracy (TA) 54 Spatial Accuracy (SA) 55 Predictability (PR) 56 Number of Input Directions (NID) 56 Consequences (CQ) 57 Importance of Actions (IoA) 57 Number of Required Actions (NRA) 58 Feedback Frequency (FF) 59 Type of Input (ToI) 59 3.3.3 Quantification of the Game Characteristics (Study 3.2) 60 Experiment Details 60 Data Analysis 61 3.3.4 Characteristics Grouping 62 3.3.5 Discussion 62 3.4 Delay Sensitivity Classification 63 3.4.1 Dataset Details 64 Crowdsourcing Game Dataset (CSGDS) 64 3.4.2 Decision Tree 65 3.4.3 Performance of the Classification 67 3.4.4 Discussion 68 3.5 User Strategy and User Inputs (Study 3.3) 69 3.5.1 Experiment Details 69 3.5.2 Influence of Player Strategies on Delay Perception 71 3.5.3 Influence of Player Strategies on User Input Characteristics 71 3.5.4 IQ and Gaming QoE 73 3.5.5 Discussion 74 3.6 Predicting the Influence of Delay on IQ 74 3.7 Impact of Performance and Delay on Gaming QoE (Study 3.4) 75 3.7.1 Experiment Details 76 3.7.2 Demographic Information of the Test Participants 76 3.7.3 Influence of Performance on Gaming QoE 77 3.7.4 Relationship Between Delay, Performance, and QoE 78 3.7.5 Discussion 79 3.8 Summary 79 4 Influence of Time-Varying Delay on Gaming QoE 81 4.1 Introduction 81 4.2 Influence of Jitter on Gaming QoE (Study 4.1) 81 4.2.1 Experiment Details 82 4.2.2 Data Analysis 84 4.2.3 Comparison of Crowdsourcing and Laboratory Study (Study 4.2) 85 Data Analysis 86 4.2.4 Discussion 87 4.3 The Serial-Position Effects of Delay on Gaming QoE 88 4.3.1 Experiment Details 89 4.3.2 Data Analysis 92 4.3.3 Discussion 93 4.4 Impact of Gamers' Adaptation to Delay on Gaming QoE 94 4.4.1 Experiment Details (Study 4.3) 95 4.4.2 Data Analysis 96 Correlation Between Subjective and Objective Performance 97 Impact of User Adaptability to Delay on User Performance 98 Impact of User Adaptability to Delay on Gaming QoE 100 4.4.3 Discussion 101 4.5 Summary 103 5 Delay Compensation Technique 105 5.1 Introduction 105 5.2 Overview of Delay Compensation Techniques 106 5.2.1 Delay Compensation on Online Gaming 106 5.2.2 Delay Compensation on Cloud Gaming 107 5.3 Proposed Technique (Study 5.1) 108 5.3.1 Experiment Details 109 5.3.2 Adaptation by Reducing the Spatial Accuracy 110 5.3.3 Adaptation by Reducing the Temporal Accuracy 111 5.3.4 Adaptation Using Both Temporal and Spatial Accuracy 112 5.3.5 Discussion 113 5.4 Extension of the Proposed Delay Compensation Technique (Study 5.2) 114 5.4.1 Experiment Details 114 Demographic Information of the Test Participants 115 5.4.2 Evaluation and Results 115 Adaptation Using Spatial Accuracy 116 Adaptation Using Temporal Accuracy 117 Adaptation Using Predictability 118 Adaptation Using Number of Required Actions 119 Adaptation Using Consequences 121 Visible and Invisible Adaptation 122 5.4.3 Discussion 124 5.5 Delay Compensation Techniques on the Variation of Delay 126 5.5.1 Game Adaptation Technique in Jitter 126 5.5.2 De-Jitter Buffering and the Adaptation 127 5.5.3 Dynamic Adaptation and Invisible Adaptation 129 5.6 Discussion and Summary 131 6 Conclusion and Outlook 133 6.1 Summary 133 6.2 Answers to Research Questions 135 6.2.1 Research Question 1 135 RQ1.1: What Are the Game Characteristics Influencing the Delay Sensitivity of Cloud Games? 135 RQ1.2: Can Games be Classified Regarding Their Delay Sensitivity Based on Expert Judgement? 136 RQ1.3: Can the Delay Sensitivity Classification Improve Gaming QoE Prediction? 136 6.2.2 Research Question 2 136 RQ2.1: What Is the Impact of Jitter on Gaming QoE? 136 RQ2.2: What Is the Impact of Serial-Position Effects on Gaming QoE? 137 RQ2.3: What Is the Impact of Frequent Delay Variation on Gaming QoE? 137 6.2.3 Research Question 3 137 RQ3.1: Can Adaptation Technique Compensate for the Influence of Delay? 137 RQ3.2: Can Adaptation Technique Compensate for the Influence of Delay Variation? 138 6.3 Contributions of the Book 138 6.4 Limitations 139 6.5 Future Work 140 A Additional Material Related to Subjective Experiments 142 B Snapshot of the Game Used in CSGDS 147 C Questionnaire Used for Expert Judgment 152 References 155 Index 163