VLC Indoor Positioning via Bayesian Fingerprint Estimation
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Solution Overview
Problem
Existing indoor localization systems, such as GPS, are inaccurate in indoor environments due to signal attenuation and obstruction, while RF-based systems face interference and bandwidth competition, necessitating an alternative for reliable location-based services.
Innovation Solution
The use of visible light communication (VLC) systems, specifically employing LEDs and Bayesian estimators like Extended Kalman Filters (EKF) or Particle Filters (PF), to perform non-line-of-sight position localization without requiring spatial geometry knowledge, using fingerprint maps generated from optical power distributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GPS signals are used for indoor localization, then outdoor positioning accuracy is achieved, but signal attenuation and obstruction cause poor penetration through buildings and walls
Solution Approach 1:
The patent replaces RF-based GPS systems with an optical system using visible light communication. LEDs transmit positioning signals through light instead of radio waves, enabling indoor localization where RF signals are blocked. The photodetector in the UE receives optical signals to determine position, substituting the mechanical/electromagnetic RF system with an optical system that penetrates building structures effectively.
2Quantity of substance
If RF-based systems are used for indoor localization, then bandwidth is available, but interference and electromagnetic compatibility concerns arise
Solution Approach 1:
The patent substitutes RF electromagnetic waves with visible light waves for communication and positioning. The optical system uses LEDs to transmit position information and a photodetector to receive it, operating in the visible spectrum rather than RF bands. This eliminates electromagnetic interference concerns while providing sufficient bandwidth for positioning data transmission.
3Measurement precision
If triangulation approach is used with VLC, then position can be determined using geometry, but at least three line-of-sight optical transmitters are required
Solution Approach 1:
The patent performs preliminary action by pre-generating fingerprint maps that contain optical power distribution information for various locations in the environment. These maps are created offline and stored in the UE or server. During positioning, the UE compares received optical signals against the pre-stored fingerprint maps using Bayesian estimation, eliminating the need for real-time line-of-sight triangulation and working effectively in NLOS conditions.
Solution Approach 2:
Instead of using geometric triangulation that requires direct line-of-sight measurement, the patent inverts the approach by using pre-collected optical power fingerprints and Bayesian probability estimation. The system transitions from deterministic geometric calculation to probabilistic pattern matching, allowing positioning without line-of-sight requirements.
4Reliability
If fingerprint map approach is used, then RSS information can be utilized for positioning, but computational complexity increases with Bayesian estimators
Solution Approach 1:
The patent implements self-service by having the UE device autonomously perform Bayesian estimation using pre-stored fingerprint maps and received optical signal measurements. The UE independently calculates position probability distributions without requiring complex centralized processing or external assistance, balancing computational load between the UE and network 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
VLC systems enable accurate indoor positioning and tracking without line-of-sight requirements, improving localization accuracy even in challenging signal conditions, such as non-line-of-sight scenarios and varying SNR, by leveraging diffuse optical sources and crowd-sourced fingerprint map generation.
Implementation Method 1
an optical emitter circuit comprising a light emitting diode (LED) and a drive circuit
Implementation Method 2
a photodetector configured to obtain information indicative of a measured characteristic of light emitted from the optical emitter
Implementation Method 3
using diffuse optical sources and crowd-sourced fingerprint map generation
Data Source
AI summary
Visible-light communication (VLC) is an optical wireless communication technique that uses light emitting diodes (LEDs) or other optical sources to transmit information to a user equipment (UE) device. An optically-based location determination approach, such as using VLC infrastructure, can meet a desire for location-based services where use of VLC can provide a solution to an indoor localization or navigation problem. A fingerprinting approach can include use of an optical received signal strength (RSS) or other information (e.g., an image of a scene) to generate a spatial fingerprint map of an area. A later-received RSS on the UE device and the prior-generated fingerprint map representative of RSS can be received, and a fingerprint map and RSS observations can be provided as inputs to a Bayesian filter, such as an Extended Kalman Filter (EKF) or a Particle Filter, to provide an estimated position for the UE device.