Smartphones in wireless communication without mobile networks A study on Android smartphones and XBee radio modules Dag Roger Stokland Rui Thesis submitted for the degree of Master in Programming and Networks 60 credits Institute of Informatics Faculty of Mathematics and Natural Sciences UNIVERSITY OF OSLO November 2016 © Dag Roger Stokland Rui 2016 Smartphones in wireless communication without mobile networks Dag Roger Stokland Rui http://www.duo.uio.no/ Print: Reprosentralen, Universitetet i Oslo Abstract Smartphones are among the most popular communication devices there are today. They have the functionality, the flexibility, the prevalence and the economic and technological growth that makes them interesting for new applications. This thesis will focus on the use of smartphones as communication terminals without the use of mobile cellular networks. It explains how smartphones can be used for communication in situations when the mobile network is out of range or not working. These situations include emergency situations in case of hurricanes or flooding, but also less demanding situations where alternative communication may be useful. This thesis compares the current communication technologies available on smartphones and explores the alternatives in order to improve the use smartphones in communication without mobile networks. Finally, the thesis proposes an implementation where a radio module is used together with an Android smartphone to create a wireless messaging system. Foreword First of all I want to thank my supervisor Joar Martin Østby. Thank you for making it possible for me to work on this thesis, and thank you for supporting and helping me through these years. Writing this thesis would have been impossible without you. I would also like to thank my family and my friends for supporting and helping me. Special thanks to Alexander Lorenzo, Hilde Stokland Rui and Odd Vidar Rui for helping me test the application. Many thanks to everyone else who I has helped me, including Josef Noll, Frank Li, Amol Pophale and the people at Sonen, Institute of informatics, University of Oslo. Through this thesis I have learned a lot, and I hope it can be of use to someone. I II Contents 1 INTRODUCTION .................................................................................................................................... 1 1.1 MOTIVATION ................................................................................................................................................ 2 1.1.1 Situations without network coverage ............................................................................................. 3 1.1.2 Why smartphones?.......................................................................................................................... 4 1.2 DEVELOPMENT CHOICES .................................................................................................................................. 5 1.3 GOALS ......................................................................................................................................................... 5 1.4 THESIS STRUCTURE ......................................................................................................................................... 6 2 BACKGROUND ...................................................................................................................................... 7 2.1 ELECTRONIC COMMUNICATION ......................................................................................................................... 7 2.2 WIRELESS COMMUNICATION ............................................................................................................................ 8 2.2.1 Modulation ...................................................................................................................................... 9 2.2.2 Radio frequencies and bands ........................................................................................................ 10 2.2.3 Regulations .................................................................................................................................... 13 2.2.4 Systems and devices ...................................................................................................................... 14 2.3 MOBILE NETWORKS AND EMERGENCY COMMUNICATION SYSTEMS FAILURES ........................................................... 17 2.4 WIRELESS MULTI-HOP NETWORKS ................................................................................................................... 18 2.5 SMARTPHONE BASED ALTERNATIVE COMMUNICATION ......................................................................................... 19 2.5.1 GoTenna ........................................................................................................................................ 20 2.5.2 Beartooth Walkie-Talkie ................................................................................................................ 20 2.5.3 Serval Mesh ................................................................................................................................... 21 2.5.4 FireChat ......................................................................................................................................... 21 2.5.5 Future applications ........................................................................................................................ 21 3 TECHNOLOGICAL POSSIBILITIES AND LIMITATIONS ............................................................................. 23 3.1 ANDROID ................................................................................................................................................... 23 3.1.1 Connectivity ................................................................................................................................... 24 3.2 ANDROID AD HOC WI-FI ............................................................................................................................... 29 3.3 EXTERNAL HARDWARE FOR COMMUNICATION ................................................................................................... 30 3.3.1 Challenges ..................................................................................................................................... 30 3.3.2 Considered hardware .................................................................................................................... 31 3.3 HARDWARE DECISION ................................................................................................................................... 38 3.3.1 XBee-PRO DigiMesh 2.4 ................................................................................................................. 38 3.3.2 Android smartphone as USB Host ................................................................................................. 39 3.3.3 Arduino as USB Host ...................................................................................................................... 40 4 DEVELOPMENT OF THE XBEE TERMINAL APP ...................................................................................... 41 III 4.1 THE XBEE TERMINAL APP .............................................................................................................................. 41 4.2 SYSTEM OVERVIEW ....................................................................................................................................... 42 4.3 ANDROID PROGRAMMING ............................................................................................................................. 43 4.3.1 Activities and Fragments ............................................................................................................... 43 4.3.2 AndroidManifest.xml ..................................................................................................................... 44 4.3.3 Intents and intent-filters ................................................................................................................ 44 4.3.4 The Android Framework ................................................................................................................ 44 4.4 XBEE TERMINAL USER INTERFACE .................................................................................................................... 45 4.4.1 Node list interface ......................................................................................................................... 46 4.4.2 Chat interface ................................................................................................................................ 46 4.4.3 Remote SMS interface ................................................................................................................... 47 4.4.4 Voice interface ............................................................................................................................... 48 4.5 USB-TO-SERIAL COMMUNICATION .................................................................................................................. 49 4.5.1 Android as USB Host ...................................................................................................................... 50 4.5.2 Arduino as USB Host ...................................................................................................................... 52 4.6 SERIAL COMMUNICATION WITH THE XBEE-PRO 2.4