Adaptive Dimming Visible Light Communication System
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Solution Overview
Problem
Existing visible light communication systems face limitations in achieving stable signal transmission and high transmission rates due to limitations in dimming control, particularly with MPPM and OFDM methods, which are susceptible to interference from rising and falling edges, leading to increased bit error rates and reduced bandwidth.
Innovation Solution
A visible light communication system with adaptive dimming using an adaptive M-PAM modulator and dual-path pulse generator for seamless switching between visible light and infrared signals, allowing for independent modulation and demodulation of signals, and dynamic adjustment of modulation orders based on light intensity and LED performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If MPPM dimming control is used in visible light communication, then brightness adjustment capability is improved, but transmission rate is limited by duty cycle and signal stability deteriorates in low-light environments
Solution Approach 1:
The patent implements dynamic switching between visible light and infrared light paths based on real-time detection of LED light output. The system continuously monitors the actual light intensity and adjusts the transmission path selection accordingly, enabling the transmission rate to adapt dynamically to changing lighting conditions and maintain high performance across the full dimming range.
Solution Approach 2:
The patent introduces an intermediary infrared light path that acts as a mediator when visible light transmission becomes unreliable. By detecting when visible light signal quality deteriorates (due to low duty cycle or LED aging), the system switches to the infrared path, which operates independently and maintains stable transmission even when visible light dimming control limits performance.
2Device complexity
If rising edge and falling edge delay times are not considered in MPPM signaling, then system complexity is reduced, but signal interference increases and bit error rate rises
Solution Approach 1:
The patent applies preliminary action by pre-calculating and compensating for the rising edge and falling edge delay times of the LED. The system determines these delay characteristics in advance and uses them to adjust the timing of subsequent transmissions, thereby preventing signal interference and bit errors before they occur, rather than reacting to them after they happen.
Solution Approach 2:
The patent implements feedback by continuously detecting the actual light output of the LED and using this information to adjust transmission parameters. The system measures the real-time light intensity and uses this feedback to optimize the timing and selection of transmission paths, dynamically compensating for delay effects and maintaining reliable communication.
3Device complexity
If visible light and infrared light are transmitted alternately without considering delay times, then device complexity is reduced, but transmission quality deteriorates due to signal interference from rising and falling edges
Solution Approach 1:
The patent applies preliminary action by pre-calculating and compensating for the rising edge and falling edge delay times of the LED. The system determines these delay characteristics in advance and uses them to adjust the timing of subsequent transmissions, thereby preventing signal interference and bit errors before they occur, rather than reacting to them after they happen.
Solution Approach 2:
The patent implements feedback by continuously detecting the actual light output of the LED and using this information to adjust transmission parameters. The system measures the real-time light intensity and uses this feedback to optimize the timing and selection of transmission paths, dynamically compensating for delay effects and maintaining reliable communication.
4Device complexity
If LED aging is not accounted for in modulation scheme, then system simplicity is maintained, but communication stability decreases over time
Solution Approach 1:
The patent implements feedback by continuously detecting the actual light output of the LED and using this information to adjust transmission parameters. The system measures the real-time light intensity and uses this feedback to optimize the timing and selection of transmission paths, dynamically compensating for delay effects and maintaining reliable communication.
Solution Approach 2:
The patent implements dynamic switching between visible light and infrared light paths based on real-time detection of LED light output. The system continuously monitors the actual light intensity and adjusts the transmission path selection accordingly, enabling the transmission rate to adapt dynamically to changing lighting conditions and maintain high performance across the full dimming range.
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 solution enables seamless and delay-less transmission of hybrid signals, reduces bit error rates, and improves transmission efficiency by adapting to LED performance, ensuring stable and high-speed communication even in low-light environments.
Implementation Method 1
a visible light emitter, connected to the adaptive M-PAM modulator, wherein the visible light emitter converts the second electrical signal into visible light
Implementation Method 2
an infrared light emitter, connected to the adaptive M-PAM modulator, wherein the infrared light emitter converts the first electrical signal into infrared light
Implementation Method 3
The first photoelectric sensor acquires light intensity of visible light emitted by the visible light emitter, and the second photoelectric sensor acquires light intensity of infrared light emitted by the infrared light emitter
Data Source
AI summary
The invention provides a visible light communication system with adaptive dimming and a modulation and demodulation method. The system includes: a source; an adaptive M-PAM modulator, separately modulating a signal transmitted by the signal source into a first and a second electrical signal; and a dual-path pulse generator, alternately generating a first and a second pulse control signal, where the first and the second pulse control signal are both periodic signals, where when a remaining operating duration of a high level of the first pulse control signal equals to a time of a rising edge of the second pulse control signal, the second pulse control signal starts to be generated, and when a remaining operating duration of a high level of the second pulse control signal is equal to a time of a rising edge of the first pulse control signal, the first pulse control signal starts to be generated.