LI-FI APPLICATION USING AMBIENT LIGHT SENSOR A Project Presented to the faculty of the Department of Computer Science California State University, Sacramento Submitted in partial satisfaction of the requirements for the degree of MASTER OF SCIENCE in Computer Science by Khushal Shingala FALL 2019 © 2019 Khushal Shingala ALL RIGHTS RESERVED ii LI-FI APPLICATION USING AMBIENT LIGHT SENSOR A Project by Khushal Shingala Approved by: __________________________________, Committee Chair Dr. Xuyu Wang __________________________________, Second Reader Dr. Jingwei Yang ____________________________ Date iii Student: Khushal Shingala I certify that this student has met the requirements for format contained in the University format manual, and this project is suitable for electronic submission to the library and credit is to be awarded for the project. __________________________, Graduate Coordinator ___________________ Dr. Jinsong Ouyang Date Department of Computer Science iv Abstract of LI-FI APPLICATION USING AMBIENT LIGHT SENSOR by Khushal Shingala Light is the fastest medium that data can be transferred through. Potential transfer speeds are 1000 times faster than radio waves can achieve. NASA claims to have had success with transferring data from spacecraft to earth and back using lasers. Space-X plan to use lasers for inter communication in their satellite network and MARS missions. This is the revolution of Li-Fi communication technology. After analysis and study of such technologies, it appears that there were certain imitations to the idea of Light fixture to phone camera data transfer. So, I’m introducing Ambient light sensor approach over camera. The goal of this project is to deliver the working actual pathway for the development of a Li-Fi system that could later be adapted to the manufacture of LED lighting systems and integrated to be used with mainstream smartphone hardware. For this project, an Arduino was the easiest way to implement a PC to output connection. A commercial cool white LED was selected for Li-Fi waves due to the centered and even light spectrum it emits. On receiver side, I used ambient light sensor which is also widely v available in all smartphones. Previously, this sensor was not used for Li-Fi communication because of very low sampling rate. So, I’m using sampling rate adjustment property to identify each transmitted signal uniquely. In this project, I’m proposing how to modify frequencies that LED transmits, how to calibrate Ambient light sensor sampling rate and how to handle the environmental noises. So that, we can identify and prove a sensor pathway that will allow the clean and rapid sample rates that we are seeking for Li-Fi communication. _______________________, Committee Chair Dr. Xuyu Wang _______________________ Date vi DEDICATION To My Parents vii ACKNOWLEDGEMENTS I thank my professor, Dr. Xuyu Wang, for his guidance and encouragement throughout the project. I thank him for helping me to shape my project idea and giving me good feedback at every step of the project. I thank professor, Dr. Jingwei Yang for reviewing my report and encouraging me. Lastly, I would like to thank my parents for trusting me and encouraging me to achieve my goals. viii TABLE OF CONTENTS Page Dedication .................................................................................................................. vii Acknowledgements ................................................................................................... viii List of Tables ................................................................................................................ x List of Figures ............................................................................................................. xi Chapter 1. INTRODUCTION ……………………………………………………………… 1 2. LITERATURE REVIEW ....................................................................................... 4 3. TECHNOLOGIES USED ....................................................................................... 6 4. OVERVIEW ........................................................................................................... 8 5. SYSTEM ARCHITECTURE ............................................................................... 16 6. BIT MAPPING ..................................................................................................... 20 7. ASCII MAPPING ................................................................................................. 33 8. ALTERNATIVE EXPERIMENTS ...................................................................... 37 9. CONCLUSION ..................................................................................................... 42 10. FUTURE WORK ................................................................................................ 43 References ................................................................................................................... 45 ix LIST OF TABLES Tables Page 1. Samsung Galaxy S9 Specifications ........................................................................19 2. Environment Light Analysis ..................................................................................22 x LIST OF FIGURES Figures Page 1. Li-Fi Technology ......................................................................................................8 2. Illuminance and Luminance ....................................................................................11 3. 10w Cool White LED .............................................................................................12 4. 5mm Cool White LED ............................................................................................13 5. 10w RGB LED ........................................................................................................14 6. Ambient Light Sensor .............................................................................................15 7. System Architecture ................................................................................................16 8. Transmitter Setup ....................................................................................................18 9. Demodulation Workflow ........................................................................................21 10. Arduino And Smartphone Setup ............................................................................24 11. Decoding Algorithm ..............................................................................................25 12. Result Snippet from Smartphone ...........................................................................26 13. 10mm LED – Brightness Vs Distance for Bit 0 ....................................................27 14. 10mm LED – Brightness Vs Distance for Bit 1 ....................................................28 15. 15mm LED – Brightness Vs Distance for Bit 0 ....................................................28 16. 15mm LED – Brightness Vs Distance for Bit 1 ....................................................29 17. Bit Error Rate For 10mm LED ..............................................................................30 18. Bit Error Rate For 15mm LED. .............................................................................30 xi 19. Angle Vs Brightness For 10mm LED ....................................................................31 20. Angle Vs Bit Error Rate For 10mm LED. .............................................................32 21. Decoded Data .........................................................................................................36 22. 5mm Cool White LED Setup .................................................................................38 23. 10w RGB LED Setup.............................................................................................40 xii 1 Chapter 1: Introduction Data transfer and communication are one of the key activities of our daily activities. Where we mostly use Bluetooth and Wi-Fi technologies. But, speed of Bluetooth is 3 Mbps or above and speed of Wi-Fi is 1300 Mbps or above, which are very limited. Currently all wireless communication cannot communicate with multiple devices at a time with same speed due to its fixed bandwidth. To resolve these issues, Professor Harald Hass who is the researcher in mobile and optical communication, gave the ideology of transmitting the data using visual light spectrum (380-740 nanometers). He proposed that how usual household LED bulb can provide the data communication to multiple computer systems with speed up to 224 Gbps. This proposed innovation got famous as Light-Fidelity (Li-Fi). It is a specific range remote communication technology dependent on LED light, and utilize the light spectrum as a data packets rather than conventional Radio Frequency as in Bluetooth or Wi-Fi. Now, the applications and innovations towards Li-Fi communication is revolutionary increasing. I have studied an IEEE paper “CSI-based fingerprinting for indoor localization: A deep learning approach” [1], which mentioned that Li-Fi communication can be used for Indoor Navigation. Indoor Navigation uses the indoor ceiling LEDs, where LEDs can send its position data. We can also use light's directional property and intensity to map the smartphone's current location and increase the accuracy at several centimeters. This can replace the static indoor maps, cost of mapping the position nodes and limited application of Global Positioning System (GPS). Currently, innovations in Li-Fi are increasing