Visible Light Communication (VLC) emerges as a new wireless communication technology with appealing benefits not present in radio communication. However, current VLC designs commonly require LED lights to emit shining light beams, which greatly limits the applicable scenarios of VLC (e.g., in a sunny day when indoor lighting is not needed). It also entails high energy overhead and unpleasant visual experiences for mobile devices to transmit data using VLC. We design and develop DarkLight, a new VLC primitive that allows light-based communication to be sustained even when LEDs emit extremely-low luminance. The key idea is to encode data into ultra-short, imperceptible light pulses. We tackle challenges in circuit designs, data encoding/decoding schemes, and DarkLight networking, to efficiently generate and reliably detect ultra-short light pulses using off-the-shelf, low-cost LEDs and photodiodes. Our DarkLight prototype supports 1.8-m distance with 1.6-Kbps data rate. By loosening up VLC's reliance on visible light beams, DarkLight presents an unconventional direction of VLC design and fundamentally broadens VLC's application scenarios.

• Paper
• Presentation: slides

	Zhao Tian, Kevin Wright, and Xia Zhou. The DarkLight Rises: Visible Light Communication in the Dark, ACM Conference on Mobile Computing and Networking (MobiCom), October, 2016, New York, USA. Best Video Award. [PDF]
	Zhao Tian, Kevin Wright, and Xia Zhou. Lighting Up the Internet of Things with DarkVLC, International Workshop on Mobile Computing Systems and Applications (ACM HotMobile), February, 2016, St. Augustine, Florida. [PDF]

We sincerely thank the reviewers for their insightful comments. We thank DartNets lab members for their support on our study. Special thanks to Abby Starr and other members in Dartmouth DALI lab for helping produce the video. This work is supported in part by the National Science Foundation under grant CNS-1552924 and CNS-1421528. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect those of the funding agencies or others.

• The Atlantic: How Light Bulbs Watch You Buy Groceries
• EE Times: Communicating Invisibly With Dimmed Down Visible Light
• Compound Semiconductor: Visible LED Communications in the Dark?
• New Electronics: Visible light communication now possible in the dark
• EurekAlert!: Dartmouth researchers' 'DarkLight' enables visible light communication in the dark