Detection of visible light communication sources over high dynamic range

Abstract

The disclosure provides detection of visible light communication sources over a high dynamic range. A visible light communication (VLC) receiver captures frames of a scene with a camera to detect flashing light signals from a VLC transmitter such as an array of LEDs. The method assembles an enhanced dynamic range image sequence from the frames. At least one VLC source is detected in the enhanced sequence, wherein the source occupies a respective subwindow within the scene. An imaging exposure such as the exposure time used for capturing images at the subwindow is optimized according to a brightness of the respective VLC source. Then a plurality of subwindow images are captured using the optimized exposure. VLC data visible in the subwindow images is then decoded.

Description

Technical field [0001] The present invention generally relates to visible light communication (VLC) for sending digital data, and more specifically, relates to the detection and isolation of multiple VLC sources in camera images and optimizing signal-to-noise ratio performance by capturing sub-window images of each VLC source And data transfer speed. Background technique [0002] Visible light-based communication (VLC) (also known as LiFi) is a wireless data communication technology that is being actively researched for automotive applications and for consumer electronics applications. Data transmission involves modulating (ie, blinking) a light source such as a light emitting diode (LED) to encode data, and receiving modulated light at a light sensor such as a photodiode or camera to decode the data. [0003] A vehicle with a VLC receiver can receive VLC signals from a fixed source (such as an LED traffic light) or from a mobile source (such as an LED signal light, such as a tail...

AI Technical Summary

Problems solved by technology

This leads to a difficult environment for detecting dark signals or signals where ON / OFF states are indistinguishable

Alternately, when imaging LiFi emitters during nighttime operations, the camera's exposure settings may cause blooming artifacts

Photodiodes will provide a large dynamic range in the analog-to-digital response, but they will not be able to distinguish data transmission from LEDs of similar intensity because photodiodes do not detect the position of the light source, only the intensity

Also, photodiodes lack the ability of cameras to locate LiFi emitters

While a camera sensor such as a CMOS based device will allow discrimination between two LED signals of similar intensity, it typically does not have sufficient dynamic range to operate in challenging daytime environments with a lot of ambient light

Additionally, there are additional challenges related to varying strength LiFi signals interfering with each other in the automotive environment and difficulty increasing data transfer rates

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