S2-PSK Optical Wireless Communication Using Dual Light Sources
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Solution Overview
Problem
Current optical wireless communication systems using LEDs and image sensors face limitations in data transmission efficiency, particularly in environments with varying frame rates and noise, such as vehicle-to-vehicle communication, due to the reliance on single light sources and inadequate noise handling.
Innovation Solution
The implementation of a Spatial 2-Phase Shift Keying (S2-PSK) modulation method using two light sources, where one light source serves as a reference and the other as a data source, with a modulator generating binary data signals that are phase-shifted relative to the reference signal, and a demodulator using artificial neural networks to accurately detect and decode the data signals amidst noise, employing line encoding and decoding to enhance data integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single light source is used for optical wireless communication, then the device complexity is reduced, but the data transmission efficiency and noise handling capability deteriorate
Solution Approach 1:
The patent divides the communication function into two separate light sources: one dedicated to transmitting data signals and another dedicated to transmitting reference signals. This segmentation allows each light source to be optimized for its specific function, improving data transmission efficiency through S2-PSK modulation while keeping the overall device complexity manageable by using standard LED components.
Solution Approach 2:
The patent transitions from temporal signal separation to spatial signal separation by using two different light sources (different spatial positions) to transmit different signal types simultaneously. This dimensional change enables continuous data transmission without temporal multiplexing overhead and allows the receiver to distinguish between data and reference signals through spatial differentiation.
2Adaptability or versatility
If conventional modulation methods are used without spatial separation, then the system is simpler to implement, but the ability to handle noise and frame rate variations deteriorates
Solution Approach 1:
The patent introduces a dedicated reference signal light source as an intermediary that provides a stable spatial reference for the receiver. This intermediary enables the system to handle noise and frame rate variations by allowing the receiver to distinguish between signal variations caused by environmental factors and actual data changes, without requiring complex error correction algorithms.
Solution Approach 2:
The patent changes the spatial parameter by using two different light source positions instead of varying temporal parameters. This parameter change fundamentally improves noise handling capability because spatially separated signals are less susceptible to temporal noise and frame rate variations, while the implementation remains relatively simple by using standard LED technology.
3Reliability
If spatial separation of data and reference signals is implemented, then communication reliability improves, but the device complexity increases
Solution Approach 1:
The patent segments the communication function into two independent light sources, each handling a specific signal type. This segmentation improves communication reliability by preventing signal interference and enabling robust demodulation through spatial differentiation, while the device complexity remains acceptable because standard LED components and basic control circuits are used.
Solution Approach 2:
The patent makes the two light sources serve multiple functions: they simultaneously provide spatial separation for reliable signal transmission and can be controlled independently for flexible data encoding. This multi-functionality approach improves communication reliability while avoiding the need for additional specialized components that would increase device complexity.
4Productivity
If two light sources are used for S2-PSK modulation, then data transmission speed and reliability improve, but the manufacturing cost and complexity increase
Solution Approach 1:
The patent segments the transmission function into two light sources to achieve S2-PSK modulation, which doubles the data transmission speed compared to conventional methods. The manufacturing cost increase is minimized by using standard LED components and simple control circuits that can be integrated into existing infrastructure.
Solution Approach 2:
The patent changes the spatial parameter by using two different light source positions to encode data at higher speeds through S2-PSK modulation. This parameter change achieves doubled transmission speed while maintaining ease of manufacture because the solution uses conventional LED technology and basic control electronics rather than requiring specialized high-speed components.
Data Source
AI summary
An optical wireless communication apparatus includes: a modulator for generating a reference signal including periodically repeating binary zeros and ones, receiving an input of a first binary data signal, and outputting a second binary data signal, wherein the second binary data signal has the same frequency as the reference signal, and has the same phase as the reference signal when the first binary data signal comprises binary zeros and has an opposite phase to the reference signal when the first binary data signal comprises binary ones, or has the same phase as the reference signal when the first binary data signal comprises binary ones and has an opposite phase to the reference signal when the first binary data signal comprises binary zeros, and a transmitter for turning a first light source on or off according to the reference signal, and turning a second light source on or off according to the second binary data signal.