Master Thesis Electrical Engineering October 2013 Energy Consumptions of Text Input Methods on Smartphones Henry C. Obison Chiagozie C. Ajuorah School of Computing and Engineering Blekinge Institute of Technology 371 79 Karlskrona Sweden This thesis is submitted to the School of Computing and Engineering at Blekinge Institute of Technology in partial fulfillment of the requirements for the degree of Master of Science in Electrical Engineering. The thesis is equivalent to 20 weeks of full time studies. Contact Information: Authors: Henry C. Obison E-mail: [email protected] Chiagozie C. Ajuorah E-mail: [email protected] External advisor: Sven Ekström Senior Software Architect Zimpl AB Jöns Filsgatan 2 21133 Malmö Sweden University advisor: Dr. Dragos Ilie Email: [email protected] Examiner: Dr. Patrik Arlos Email: [email protected] School of Computing and Engineering Internet : www.bth.se/com Blekinge Institute of Technology Phone : +46 455 38 50 00 371 79 Karlskrona Fax : +46 455 38 50 57 Sweden ii Abstract Mobile computing devices, in particular smartphones are powered from Lithium-ion batteries, which are limited in capacity. With the increasing popularity of mobile systems, various text input methods have been developed to improve user experience and performance. Briefly, text input method is a user interface that can be used to compose an electronic mail, configure mobile Virtual Private Network, and carryout bank transactions and online purchases. Efficient energy management in these systems requires an extensive knowledge of where and how the energy is being used. This thesis investigates the energy consumption of text input methods on various smartphones. Hence, the authors modeled the energy consumption profile of text input methods on smartphones and analyze the energy usage benchmarks of the battery. This paper presents a systematic technique to conduct application specific measurements. The data analysis showed substantial variations in the energy consumptions of various text input methods on a smartphone. Keywords: Energy consumption, Power Monitor, Smartphones, Text input methods. i Acknowledgements We are very grateful to our thesis supervisor Dr. Dragos Ilie for his advice and timely feedbacks in this thesis. Our gratitude also goes to Dr. Patrik Arlos for his suggestion on Energy measurement. We are indeed grateful to Assoc. Prof. Claes Jogréus for validating the statistical analysis used in this thesis. We are thankful to Prof. Wlodek Kulesza for his guidance on referencing and research methods. We appreciate the numerous strategic supports of Prof. Tony Gorschek and Prof. Markus Fiedler during this thesis. Our special thanks go to all the people who participated in filling-out the questionnaires. We are very thankful to the Zimpl AB for entrusting us with this research project. Our profound gratitude goes to our external supervisor Sven Ekström, Charlotta Tönsgård, and all the staff of Zimpl AB for their immense support during this thesis. To our family and friends, we are indebted to you for your unconditional supports. Henry C. Obison Chiagozie C. Ajuorah ii Contents Abstract i Acknowledgements ii Contents iii List of Figures v List of Tables vi List of Acronyms viii 1 Introduction 1 1.1 Background ........................................................................................... 2 1.2 Objective ............................................................................................... 4 1.3 Research Questions ............................................................................... 4 1.4 Research Method .................................................................................. 4 1.5 Thesis layout ......................................................................................... 5 2 Literature Review 7 2.1 Energy Consumption on Smartphones ................................................. 7 2.2 Energy Meters ....................................................................................... 7 2.2.1 Component Level ............................................................................................. 8 2.2.2 Device Level .................................................................................................... 9 2.3 Technologies of Text Inputs ................................................................. 9 2.4 Touchscreen Mechanisms ..................................................................... 9 2.5 Smartphone Operating Systems .......................................................... 10 2.6 Smartphone Input Methods ................................................................. 10 2.6.1 SwiftKey Flow ............................................................................................... 11 2.6.2 Swype ............................................................................................................ 11 2.6.3 Zimpl ............................................................................................................. 12 2.7 Quality of Experience ......................................................................... 12 3 Implementation 14 3.1 Measurement Set-up ........................................................................... 14 3.2 Control Protocol and Power Monitor Data ......................................... 15 3.3 Battery By-pass Modification and Testing ......................................... 15 3.4 Power Monitor and PowerTool software ............................................ 16 3.4.1 Power-up a Smartphone using PowerTool software ...................................... 16 3.4.2 Statistics and other Settings ........................................................................... 17 3.4.3 Data Sampling ............................................................................................... 17 3.5 Modeling Energy consumption profile of Text input methods........... 17 3.5.1 Power measurement precautions .................................................................... 17 iii 3.5.2 Idle mode ....................................................................................................... 18 3.5.3 Active mode ................................................................................................... 19 3.6 Data Collection ................................................................................... 21 3.7 Safety Recommendation ..................................................................... 21 4 Results and Discussion 22 4.1 Analysis of Energy.............................................................................. 22 4.1.1 Energy consumption profile: Idle mode ......................................................... 23 4.1.2 Energy consumption profile: Active mode .................................................... 25 4.2 Energy consumption model of Text input methods ............................ 26 4.3 Testing Energy variations with ANOVA............................................ 27 4.4 Battery-life Estimation ........................................................................ 31 4.5 Validity of Results .............................................................................. 32 5 Survey Results 33 5.1 Network Usage ................................................................................... 33 5.2 Smartphone user experience ............................................................... 34 6 Conclusion 38 A PowerTool software and Power Monitor hardware specifications 40 A.1 Hardware and Software Requirements for the Workstation ............... 40 A.2 Data Exporting Features of the Power Monitor .................................. 40 A.3 Electrical Specifications of Power Monitor and AC Power Adapter . 41 B Experimental data 42 B.1 Laboratory pictures ............................................................................. 42 B.2 Average Power Consumptions - Idle mode ........................................ 42 B.3 Average Power Consumptions - Active mode .................................... 43 B.3.1 Active mode power data measured on Samsung Galaxy S3 4G .................... 43 B.3.2 Active mode power data measured on HTC Desire ....................................... 45 B.3.3 Active mode power data measured on Samsung Galaxy Nexus I9250 .......... 46 B.3.4 Data for ANOVA Two-factor with replication .............................................. 47 B.4 MATLAB Function Code ................................................................... 50 C Specifications of Smartphones 52 C.1 Specifications of Smartphones............................................................ 52 C.2 Specifications of HTC Desire ............................................................. 52 C.3 Specifications of Samsung Galaxy Nexus I9250 ................................ 53 D Survey Questionnaire 54 References 57 iv List of Figures Fig. 1.1 Shannon’s noisy channel model and Text input. ................................. 2 Fig. 1.2 Layout of capacitive touchscreen. ........................................................ 3 Fig. 2.1 Power profiling and Battery life tests................................................... 8 Fig. 2.2 SwiftKey Flow. .................................................................................. 11 Fig. 2.3 Swype input method. .......................................................................... 11 Fig. 2.4 Zimpl tap and slide. ............................................................................ 12 Fig. 3.1 Measurement set-up overview. .........................................................