Passive Optical Identifier Tags for VLC Indoor Positioning
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Solution Overview
Problem
Conventional visible light communication (VLC) based indoor positioning systems are costly, energy-intensive, and complex due to the use of active devices for receiver-side information processing and localization, which limits their efficiency and scalability in indoor environments.
Innovation Solution
A VLC-based system employing passive optical identifier tags that reflect unique wavelengths, using a light source, a receiver with an array of photodiodes, and a processing system to analyze power profiles and identify the position and identity of tags, enabling cost-effective and efficient localization without the need for active devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If active devices like detectors and sensors are used at user terminals for VLC-based indoor positioning, then positioning functionality is achieved, but cost, energy consumption, and complexity increase
Solution Approach 1:
Instead of placing active detection devices at the mobile user terminal, the patent inverts the architecture by placing passive optical identifier tags on the user terminal and keeping the active light source and detector at the fixed infrastructure. This inversion eliminates the need for complex active devices in mobile terminals while maintaining positioning functionality.
Solution Approach 2:
The patent replaces expensive, complex active detectors and sensors with inexpensive passive optical identifier tags. These passive tags have no moving parts, require no power, and are much simpler in construction, effectively serving as disposable or low-maintenance components that dramatically reduce system complexity and cost.
2Measurement precision
If active devices are deployed on mobile users for localization, then positioning accuracy is achieved, but energy consumption and cost increase
Solution Approach 1:
The passive optical identifier tags on mobile users automatically reflect incoming light from ceiling-mounted LEDs without requiring any power consumption from the mobile device. The tags passively modulate the reflected light based on their unique identification patterns, enabling localization without draining mobile device batteries.
Solution Approach 2:
The patent shifts the energy burden from mobile users to the fixed infrastructure. Instead of mobile devices consuming energy to transmit signals, the fixed LED ceiling provides continuous illumination and the passive tags on mobile devices simply reflect this light, eliminating mobile energy consumption for positioning.
3Reliability
If conventional VLC-based positioning techniques are used with active devices, then positioning is achieved, but device cost and system complexity increase
Solution Approach 1:
The patent replaces expensive active electronic components (detectors, sensors, processors) with inexpensive passive optical elements. The passive optical identifier tags can be manufactured using simple optical coatings or dichroic mirrors, making them orders of magnitude cheaper than active devices while maintaining positioning capability.
Solution Approach 2:
The patent extracts the active components from the mobile user terminal and relocates them to the fixed infrastructure. By removing detectors, sensors, and processing units from mobile devices and placing only passive reflective tags there, the system dramatically reduces device cost while centralizing complexity in the fixed ceiling-mounted units.
4Ease of operation
If mobile devices with active components are used for positioning, then localization function is provided, but device fragility and maintenance requirements increase
Solution Approach 1:
The passive optical identifier tags are extremely durable with no moving parts, electronic components, or power requirements. They can be manufactured as simple optical coatings or solid-state reflective elements that are resistant to shock, vibration, and environmental conditions, making them far more reliable than fragile mobile devices with batteries and circuits.
Solution Approach 2:
The passive tags require no maintenance, calibration, or power management. They automatically perform their identification function by reflecting incoming light according to their optical properties, eliminating all maintenance requirements associated with active electronic components in mobile devices.
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
The system achieves accurate and efficient localization of targets using passive optical identifier tags, reducing costs and complexity while improving energy efficiency and scalability, allowing for precise identification of multiple targets in indoor environments.
Implementation Method 1
Each passive optical identifier tag reflects light at a unique set of wavelengths inferred by a corresponding reflection sequence
Implementation Method 2
The array of photodiodes is configured to receive a laser power and the reflected visible light at one or more pre-configured wavelengths at the same time
Data Source
AI summary
One or more systems and methods for identifying one or more passive optical identifier tag from a plurality of passive optical identifier tags is provided. The method includes emitting light from a light source device. Further, the method includes transmitting, by said plurality of passive optical identifier tags, reflected light to a receiver. The method further includes reflecting, by the plurality of passive optical identifier tags, the emitted light with its unique set of wavelengths, said set of wavelengths being inferred by the corresponding reflection sequence.