Visible Light Communication Location Correction for Mobile Shadowing
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Solution Overview
Problem
Extending visible light communication to mobile devices is challenging due to issues like bandwidth sharing and shadowing, especially when using ambient lighting, which is less predictable than radio waves and sensitive to device orientation.
Innovation Solution
A location-aware communication system that uses light transmission units with identifiers, a mobile device with a light sensor and orientation sensing system to determine its location by analyzing light intensity and correcting for orientation, allowing dynamic clustering of light fixtures to follow the user and reduce shadowing, and integrating dead reckoning for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If visible light communication is used for mobile devices, then communication capability is provided, but location determination becomes inaccurate due to sensitivity to device orientation
Solution Approach 1:
The system corrects light intensity measurements by adjusting for device orientation parameters (roll, pitch, yaw) obtained from the orientation sensing system. By changing the measurement parameters based on orientation data, the system compensates for the sensitivity of light sensors to angular changes, thereby maintaining location determination accuracy while preserving communication capability.
Solution Approach 2:
The orientation sensing system continuously monitors device orientation and feeds this information back to the location determination algorithm. This feedback loop allows the system to dynamically adjust location calculations based on real-time orientation data, correcting for the confounding effect of orientation sensitivity on light intensity measurements.
2Productivity
If multiple light fixtures are used for communication, then bandwidth is increased, but shadowing effects increase and system complexity increases
Solution Approach 1:
The system dynamically clusters light fixtures into mobile device-specific groups based on real-time location determination. Instead of statically assigning fixtures, the clustering changes dynamically as devices move, allowing the system to adapt the number and composition of active fixtures per device. This reduces overall system complexity while maintaining high bandwidth through dynamic resource allocation.
Solution Approach 2:
The system segments the entire light fixture infrastructure into separate, device-specific clusters. Each mobile device receives dedicated clusters of light fixtures for its communication needs, isolating interference and shadowing effects to specific segments rather than affecting the entire system. This segmentation allows independent optimization of each device's communication channel.
3Ease of manufacture
If light fixtures are fixed for communication, then infrastructure is simple, but shadowing occurs during handoff between fixtures
Solution Approach 1:
The system transitions from fixed, static light fixture assignment to dynamic, mobile-device-following clusters. As devices move through the environment, the clusters of light fixtures automatically reconfigure to track and follow the devices, ensuring continuous communication without shadowing interruptions. This dynamic adaptation maintains reliability while keeping the physical infrastructure simple and fixed.
Solution Approach 2:
The location server acts as an intermediary that coordinates between the fixed light fixtures and mobile devices. It processes location data, determines optimal fixture clusters, and manages handoffs between fixtures, eliminating the need for complex mobile infrastructure while preventing shadowing-related communication failures through intelligent coordination.
4Area of stationary object
If ambient lighting is used for communication, then existing infrastructure is utilized, but signal predictability decreases compared to radio waves
Solution Approach 1:
The system replaces the inherent unpredictability of ambient light propagation with a controlled measurement and correction approach. By using the orientation sensing system to characterize and compensate for light propagation variations, the system creates predictable effective channels from an otherwise unpredictable physical medium, enabling reliable communication over existing ambient lighting infrastructure.
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 system enables accurate mobile device localization without auxiliary hardware, reduces shadowing, and enhances communication efficiency by dynamically allocating light transmitters, providing a shadow-free experience similar to wireless radio signals while being compatible with ambient lighting.
Implementation Method 1
The mobile device includes a light sensor for receiving light from a set of the light transmission units and processing that light to extract the identifier of the light transmission units of the set and an intensity of the light signal
Data Source
AI summary
A visible light communication system identifies the location of a mobile device using light intensities corrected by mobile device orientation. This location can be used to generate a dynamic cluster of visible light transmitters about the mobile device providing improved “handoff” between transmitters and reduced shadowing.