VLC Source Detection via Dynamic Subwindow Exposure

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Solution Overview

Problem

Visible light communication (VLC) systems face challenges in detecting and distinguishing multiple VLC sources in outdoor automotive environments, particularly with varying light intensities and ambient light interference, which affects data transmission rates and accuracy.

Innovation Solution

The method involves capturing high dynamic range (HDR) images by combining frames with varying exposure durations to detect VLC sources, determining optimal exposure settings for each source, and using subwindowing to isolate and decode data from individual VLC sources, thereby maximizing data transfer rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a camera with wide field of view is used to detect multiple VLC sources, then the ability to detect and track multiple sources is improved, but the image quality and signal-to-noise ratio deteriorate due to distributing sensor pixels across a larger area

Engineering Contradiction:

Improveability to detect and track multiple VLC sourcesVSAvoidsignal-to-noise ratio

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent divides the image frame into multiple regions of interest (ROIs) corresponding to different VLC sources. Instead of processing the entire wide-field image uniformly, the system segments the frame and focuses computational resources on specific subregions containing active transmitters, thereby maintaining high signal-to-noise ratio while tracking multiple sources simultaneously

Inventive Principle:

Principle #1Segmentation

2Ease of operation

If a global exposure time is used for the entire image frame, then the exposure settings are simple to manage, but the data transmission rate deteriorates when VLC sources have varying light intensities

Engineering Contradiction:

Improveexposure settings managementVSAvoiddata transmission rate

Core Design Contradiction:

Ease of operationVSProductivity

Solution Approach 1:

The patent implements dynamic, per-ROI exposure time adjustment based on the detected intensity of each VLC source. The system continuously adapts exposure parameters for different regions independently, allowing optimal signal capture for each transmitter regardless of intensity variations, thereby maximizing data transmission rates across multiple sources with varying brightness levels

Inventive Principle:

Principle #15Dynamics

3Measurement precision

If the exposure time is increased to capture dim VLC sources, then the detection of low-intensity sources is improved, but blooming artifacts occur when imaging bright LiFi transmitters

Engineering Contradiction:

Improvedetection of low-intensity VLC sourcesVSAvoidblooming artifacts

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent applies different exposure times to different regions of interest based on the intensity characteristics of individual VLC sources. Dim sources receive longer exposure times for adequate signal capture, while bright sources are captured with shorter exposure times to prevent saturation and blooming artifacts. This localized exposure strategy allows simultaneous optimization for both low-intensity and high-intensity transmitters within the same image frame

Inventive Principle:

Principle #3Local quality

4Adaptability or versatility

If multiple VLC sources with varying intensities are detected simultaneously, then the coverage of the communication system is improved, but the difficulty of distinguishing and decoding individual sources increases

Engineering Contradiction:

Improvecoverage of communication systemVSAvoiddistinguishing and decoding individual sources

Core Design Contradiction:

Adaptability or versatilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent segments the image frame into distinct regions of interest, each associated with a specific VLC source. By spatially separating the detection and decoding processes for each source into dedicated ROIs, the system eliminates interference between simultaneous transmissions from multiple sources, making it feasible to distinguish and decode individual sources even when they transmit at different intensities simultaneously

Inventive Principle:

Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables reliable detection and decoding of VLC sources in challenging environments, enhancing data transfer rates and accuracy by optimizing exposure settings and using subwindowing to focus on individual light sources, thus overcoming the limitations of global exposure times and ambient light interference.

Implementation Method 1

receiving the modulated light at a light sensor such as a photodiode or a camera to decode the data

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS10193627B1Detection of visible light communication sources over a high dynamic range

Publication Date: 2019.01.29 FORD GLOBAL TECH LLC

AI summary

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.