Coded Light Signaling for Accurate Mobile Device Location
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Solution Overview
Problem
Existing methods for locating a person in a crowd, such as text messaging or indoor positioning systems, are often inaccurate and prone to errors, making it difficult to find someone in a crowd effectively.
Innovation Solution
A method where mobile devices transmit and receive coded light signals, allowing one device to identify and display the location of another device by modulating the light source's color, intensity, and duty cycle, enabling accurate location determination in a group of people.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If text messaging or indoor positioning systems are used to locate a person in a crowd, then communication between users is enabled, but accuracy and reliability of location determination deteriorates
Solution Approach 1:
The patent replaces traditional mechanical/electronic positioning systems (GPS, indoor positioning) with an optical signaling system. Mobile devices emit coded light signals that can be detected by camera sensors, transforming the location determination problem from radio-frequency-based to optical-based measurement, thereby achieving higher accuracy and reliability in crowded environments.
Solution Approach 2:
The patent utilizes color-coded light signals emitted by mobile devices to represent different location information or device identifiers. By modulating the color, intensity, and duty cycle of LED light sources, the system encodes position data in a visually detectable manner, enabling accurate location determination through optical rather than electronic means.
2Measurement precision
If coded light signals are emitted by mobile devices, then location accuracy is improved, but device complexity increases
Solution Approach 1:
The patent leverages existing multi-functional components in mobile devices: standard LED light sources (originally for display or notification) are repurposed for coded signal emission, and built-in camera sensors (originally for photography) are used for detecting and decoding the light signals. This approach achieves high measurement precision without adding dedicated specialized hardware, thereby limiting the increase in device complexity.
Solution Approach 2:
The mobile device's existing light source and camera system serve dual purposes: the light source communicates location information optically while the camera receives and decodes signals from other devices. The device essentially uses its own built-in components for both transmitting and receiving location data, reducing the need for additional external equipment.
3Loss of information
If light sources are modulated to encode location data, then information transmission accuracy is improved, but energy consumption increases
Solution Approach 1:
The patent employs periodic modulation of the light source at specific duty cycles to encode location information. By varying the duty cycle (the ratio of on-time to total period), the system transmits data efficiently using pulsed rather than continuous illumination, thereby reducing overall energy consumption while maintaining high transmission accuracy through the coded signal patterns.
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 provides an accurate and error-proof way to locate a person in a crowd by using coded light signals, allowing users to visually identify the location of the emitting device, even in a dense environment, with the added benefit of using existing camera technology and network synchronization for robust detection.
Implementation Method 1
driving a light source of a light emitting mobile device such that it emits light being coded according to the code by controlling a time-varying, modulated current to the light source to produce variations in the light output by modulating the color, intensity and/or duty cycle of the light
Implementation Method 2
capturing, by a light receiving mobile device, a stream of images comprising the light emitted by the light source
Data Source
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AI summary
A method (800) of locating a mobile device in a group of mobile devices is disclosed. The method comprises transmitting (802) a request message defining a code, receiving (804) the request message, driving (806) a light source of a light emitting mobile device such that it emits light being coded according to the code, detecting (808), by a light receiving device, the light emitted by the light source, retrieving (810) the code from the light, identifying (812) the light emitting mobile device based on the code, and providing (814) an indicator on the light receiving mobile device, the indicator indicating the location of the light emitting mobile device.