Ph.D. DISSERTATION DEFENSE

Candidate: Bo Liu Degree: Doctor of Philosophy School/Department: Charles V. Schaefer, Jr. School of Engineering and Science / Electrical and Computer Engineering Date: Thursday, March 18, 2021 Time/Location: 9:00a.m. / Zoom meeting ID: 506 875 4099

Title: Towards Visible Light Communication Using Mobile Devices

Chairperson: Dr. Yudong Yao, Department of Electrical and Computer Engineering, Stevens Institute of Technology

Committee Members: Dr. Yingying Chen, Department of Electrical and Computer Engineering, Rutgers University Dr. Hong Man, Department of Electrical and Computer Engineering, Stevens Institute of Technology Dr. Hui Wang, Department of Computer Science, Stevens Institute of Technology

ABSTRACT

New Mobile devices equipped with variety of sensors have been pervasively used by people in nowadays. These mobile devices have the capability to sense data with Visible Light Communication (VLC). VLC grows rapidly in the past decade for many applications (e.g., indoor data transmission, human sensing, and visual MIMO) due to its RF interference immunity and inherent high security. However, most existing VLC systems heavily rely on fixed infrastructures with less adaptability to emerging light weight mobile applications. Light storage, a low-cost portable VLC system is explored by taking the advantage of commercial smartphone flashlight as the transmitter and solar panel equipped with both data reception and energy harvesting modules as the receiver. The system can achieve concurrent data transmission and energy harvesting from the visible light signals and is validated in both indoor and outdoor environments. Then a secure visible light communication system is presented leveraging the unique color shift property over screen-to-camera channel. To facilitate such design, two secret key mapping algorithms, key matching based and nearest next hop based, are developed to convert the secret key into gridded optical patterns on screen, which can only be correctly recognized by the legitimate user through an accessible region and allow regular data stream transmission through valid grids. After secured VLC channel, a no physical contact VLC-based gesture recognition system, AirSlide, is developed utilizing proximity and light sensors on COTS mobile devices. The designed algorithm captures key factors of unknown data when the operating finger moves in detection zone and compares it with training data so that the user can experience a new secured way to do no physical contact gesture control on mobile device without involving camera.