DSM-PSK Optical Wireless Transmission Using Image Sensors
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Solution Overview
Problem
Current Visible Light Communication (VLC) technologies, such as IEEE 802.15.7, are limited by the need for dedicated communication apparatuses and do not efficiently utilize image sensors for data transmission, which restricts their application in optical wireless communication systems.
Innovation Solution
The DSM-PSK optical wireless communication method uses LEDs and image sensors to transmit data by converting binary signals into global phase shift signals, creating ordered pulse wave signals with specific phases and duty ratios, and turning light sources on and off accordingly, allowing for efficient data transmission using a modulator and demodulator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dedicated communication apparatuses such as VLC dongles are used for data transmission, then communication functionality is achieved, but device complexity and cost increase
Solution Approach 1:
The patent enables image sensors, originally designed for imaging purposes, to perform dual functions by simultaneously capturing images and detecting optical signals for communication. This multi-functionality eliminates the need for dedicated communication apparatuses, reducing device complexity while maintaining reliable communication functionality through phase-shift keying modulation detected by the image sensor
Solution Approach 2:
The image sensor serves itself by utilizing its existing imaging capability to also perform communication functions. The sensor processes both imaging data and communication signals through its inherent photodetection properties, eliminating the need for separate dedicated communication hardware and reducing overall system complexity
2Adaptability or versatility
If image sensors are used instead of photo diodes for optical wireless communication, then versatility and ease of operation improve, but signal detection precision and reliability may deteriorate
Solution Approach 1:
The patent segments the image sensor's detection capability by assigning specific pixel regions or time periods dedicated to communication signal detection, while other regions or periods handle imaging. This segmentation allows the image sensor to maintain high signal detection precision for communication purposes while preserving its imaging versatility
Solution Approach 2:
The patent employs periodic modulation schemes where the image sensor alternates between imaging mode and communication signal detection mode. During specific time periods, the sensor focuses on detecting phase-shifted communication signals with high precision, while other periods are dedicated to imaging, thus maintaining both versatility and detection precision
3Productivity
If multiple light sources are used for DSM-PSK modulation, then data transmission efficiency improves, but device complexity increases
Solution Approach 1:
The patent combines multiple light sources into a unified modulation system where all sources are controlled by a single modulator to generate phase-shifted signals. This merging approach maintains data transmission efficiency through parallel light source activation while reducing device complexity by using a centralized control mechanism rather than separate modulation circuits for each light source
4Productivity
If high-order phase shift keying (M≥3) is used, then data transmission rate improves, but difficulty of detecting and measuring increases
Solution Approach 1:
The patent introduces a reference signal as an intermediary that the image sensor compares against received phase-shifted signals. This reference signal serves as a benchmark for determining the phase shift amount, making high-order phase shift detection (M≥3) more accurate and less difficult by providing a clear comparison standard rather than requiring direct absolute phase measurement
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 method enables efficient wireless communication using LEDs and image sensors, particularly for applications like vehicle-to-vehicle communication, by effectively separating and demodulating data signals from reference signals, supporting both global and rolling shutter methods, and handling variable frame rates and noise environments.
Implementation Method 1
converting, by the modulator, the binary data signal into a global phase shift signal having an integer value from 0 to M−1
Implementation Method 2
turning on and off, by a transmitter, each of light sources of the reference light source group including M ordered light sources, according to each pulse wave signal of the reference signal group
Implementation Method 3
receiving, by a receiver, consecutively photographed images from an image sensor; detecting, by a demodulator, ON/OFF states of a reference light source group including M ordered light sources and a data light source group including M ordered light sources on the images
Data Source
AI summary
A DSM-PSK optical wireless transmission method includes the steps of: receiving a binary data signal, allowing a modulator to convert the binary data signal into a global phase shift signal, generating a reference signal group including M number of pulse signals having the same period, the same duty ratio of d/M, mutually different phases, and a determined sequence, generating a data signal group including M number of pulse signals having a determined sequence, the pulse signals having been obtained by phase-shifting the reference signal group according to the global phase shift signal, flickering each light source of a reference light source group including M number of light sources having a determined sequence, according to each pulse signal of the reference signal group, and flickering each light source of a data light source group including M number of light sources having a determined sequence, according to each pulse signal of the data signal group.