Indoor Tag Positioning Using O-OFDM Anchor Clusters
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Solution Overview
Problem
Current indoor positioning technologies face challenges in achieving precise location determination of tags in indoor environments, particularly due to interference and shadowing issues with existing light-based methods, and there is a need for an alternative solution that provides high precision and reliability.
Innovation Solution
A system comprising a network of anchors emitting light signals with distinct pilot signals using different frequencies and time slots, a controller to manage anchor clusters, and an evaluator to determine the tag's position based on received light signals, utilizing optical orthogonal frequency-division multiplexing (O-OFDM) for accurate positioning, even in the presence of interference or shadowing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If light-based positioning methods are used for indoor positioning, then positioning can be achieved without radio frequency interference, but precision is reduced due to interference and shadowing issues
Solution Approach 1:
The system segments the positioning function into multiple distributed anchors that emit light signals with distinct pilot signals. Each anchor operates independently, and the receiver processes signals from multiple anchors to determine position, thereby reducing the impact of shadowing from any single anchor while maintaining high precision through collective signal processing
Solution Approach 2:
The system changes the parameter of light signal modulation by using orthogonal frequency-division multiplexing (OFDM) with distinct pilot signals at different frequencies and time slots. This parameter change enables the receiver to distinguish between signals from different anchors even in the presence of interference and shadowing, simultaneously improving reliability and precision
2Measurement precision
If multiple anchors emit light signals simultaneously for positioning, then positioning accuracy can be improved through multiple measurements, but signal interference increases
Solution Approach 1:
The system implements periodic action by assigning different time slots to different anchors for emitting pilot signals. Anchors transmit signals in a time-division manner within periodic frames, ensuring that multiple measurements can be taken over time without simultaneous signal interference, thereby maintaining positioning accuracy while avoiding interference
Solution Approach 2:
The system resolves signal interference by adding frequency and time dimensions to the signal space. Each anchor transmits pilot signals at distinct frequencies and/or time slots, creating an orthogonal signal structure. This dimensional expansion allows the receiver to separate and process signals from multiple anchors simultaneously without interference, improving positioning accuracy
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 precise indoor positioning with centimeter-level accuracy by effectively managing anchor clusters and using O-OFDM to separate and identify pilot signals, enabling reliable determination of the tag's position even in environments with limited anchor availability or shadowing.
Implementation Method 1
a plurality of anchors, wherein the anchors of the plurality of anchors are located at known positions and are configured to emit light signals
Implementation Method 2
utilizing optical orthogonal frequency-division multiplexing (O-OFDM) for accurate positioning
Data Source
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AI summary
The invention refers to a system (1) for determining a position of a tag (2). Anchors (3) of a plurality of anchors (3) are located at known positions and are configured to emit light signals. A controller (4) controls anchors (3) of the plurality of anchors (3) with regard to emitting light signals and treats a given number of anchors (3) of the plurality of anchors (3) as an anchor cluster such that anchors (3) belonging to the anchor cluster emit light signals comprising different pilot signals using different frequencies and/or different time slots. At least one receiver (5) associated with the tag (2) receives light signals. Finally, an evaluator (6) determines the position of the tag (2) based on light signals received by the receiver (5). The invention also refers to a corresponding method.