Optical Wireless Communication Using Dual-Wavelength Segmentation
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Solution Overview
Problem
Optical wireless communication systems face challenges in maintaining signal quality when the illumination light source is dimmed or turned off, as highly sensitive detectors may saturate or distort signals, and the human eye perceives average luminosity rather than rapid variations, limiting data transmission capabilities.
Innovation Solution
The system employs a secondary light source with non-overlapping wavelength ranges to continue data transmission when the illumination light is dimmed or off, using a controller to adjust the intensity of the secondary light source to compensate for dimming, allowing data transmission even in low-light conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the illumination light source is dimmed to achieve lower illumination levels, then the illumination intensity is reduced, but the signal quality of the optical wireless communication deteriorates
Solution Approach 1:
The system divides the communication function into two separate light sources: one dedicated to illumination and another dedicated to data transmission. This segmentation allows each light source to be optimized for its specific function, enabling the illumination light to be dimmed without compromising communication signal quality, as the data transmission light operates independently.
Solution Approach 2:
The system transitions from using a single light source for both illumination and communication to using multiple light sources with different wavelength ranges. By adding the second light source operating in a different spectral dimension (visible vs. infrared), the system can maintain communication performance across varying illumination levels.
2Illumination intensity
If the illumination light source is turned off to achieve complete darkness, then the illumination intensity is reduced to zero, but optical wireless communication becomes impossible
Solution Approach 1:
The system separates the illumination function from the communication function by using distinct light sources. When complete darkness is required, the illumination light can be turned off while the data transmission light continues to operate independently, maintaining communication capability without providing visible illumination.
Solution Approach 2:
The second light source acts as an intermediary for data transmission when the primary illumination light is off. This intermediary light source operates in the infrared spectrum, which is invisible to the human eye, allowing communication to proceed without providing visible light.
3Measurement precision
If a highly sensitive detector is used to receive low luminosity level signals, then the detector sensitivity is increased, but signal distortion and saturation issues occur
Solution Approach 1:
The system changes the operating parameters of the light source by using a second light source with higher output power in the infrared spectrum. This compensates for the low luminosity conditions and allows the use of standard detectors without saturation, while the modulated signal remains detectable through its characteristic frequency signature.
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 enhances signal quality and link reliability by maintaining data transmission across a wide range of brightness settings, including low-light conditions, by using invisible light that is not perceivable to the human eye, thereby overcoming the limitations of traditional optical wireless communication systems.
Implementation Method 1
Data may be transmitted using light by modulating an intensity of the light. The optical signal has rapid changes in luminosity levels.
Implementation Method 2
The further light may have a wavelength between 700 nm and 1 mm
Implementation Method 3
The further light may have a wavelength below 400 nm
Data Source
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Figure 5
AI summary
An optical wireless communication system comprising a transmitter apparatus that comprises: an illumination light source configured to output visible light for illumination purposes, and a controller configured to control operation of the illumination light source to produce modulation of the visible light to provide an optical wireless communication signal representing data; a further light source configured to output further light, wherein the controller is configured to control operation of the further light source to produce modulation of the further light to provide a further optical wireless communication signal representing substantially the same data, wherein the visible light and the further light have different wavelengths.