Towards High-Speed Passive Visible Light Communication with Event Cameras and Digital Micro-Mirrors

TL;DR

This work significantly extends this work by proposing a massive spatial data channel framework for DMDs, where individual channels can be decoded in parallel using an event camera at the receiver, markedly surpassing current benchmarks by 16x.

Abstract

Passive visible light communication (VLC) modulates light propagation or reflection to transmit data without directly modulating the light source. Thus, passive VLC provides an alternative to conventional VLC, enabling communication where the light source cannot be directly controlled. There have been ongoing efforts to explore new methods and devices for modulating light propagation or reflection. The state-of-the-art has broken the 100 kbps data rate barrier for passive VLC by using a digital micro-mirror device (DMD) as the light modulating platform, or transmitter, and a photo-diode as the receiver. We significantly extend this work by proposing a massive spatial data channel framework for DMDs, where individual channels can be decoded in parallel using an event camera at the receiver. For the event camera, we introduce event processing algorithms to detect numerous channels and decode bits from individual channels with high reliability. Our prototype, built with off-the-shelf event cameras and DMDs, can decode up to $\sim$2,000 parallel channels, achieving a data transmission rate of 1.6 Mbps, markedly surpassing current benchmarks by 16x.

Figures (21)

• Figure 1: Unlike PhotoLink xu2022exploiting, which configures all micro-mirrors in the DMD to the same state to create a single channel, Selene establishes multiple concurrent VLC channels by controlling clusters of mirrors independently. Moreover, the event camera is selected for its superior temporal resolution compared to conventional RGB cameras and its higher spatial resolution relative to photo-diodes.
• Figure 2: The VLC channels can be distributed in a visual shape (character A) and projected to on light cover cases (a) and ground/walls (b).
• Figure 3: (a) The pixels in event cameras can independently and continuously capture changes in light intensity, where $X,Y$ are the pixel positions and $T$ is the timestamp. (b) During the exposure time $T_{e}$, only one column of pixels is sampled based on the rolling shutter mechanism of COMS cameras, while $T_{f}$ represents the frame rate.
• Figure 4: The large intensity change may trigger multiple events to be generated.
• Figure 5: The ratio between duplicated events and unique events vs. the received light intensity change.