RFID Tag Read Accuracy Using Power Scaling Factor

Solution Overview

Problem

Current RFID tag systems struggle to determine the three-dimensional read accuracy due to computational complexity and memory requirements when considering various orientations and polarizations, as existing methods like the Friis Equation are impractical for evaluating the operational volume of RFID tags in three-dimensional space.

Innovation Solution

A method using a 3-D matrix to represent theta, phi, and polarization values for RFID tags, calculating power received at different positions, and determining a power scaling factor to assess read accuracy across specified discretizations, allowing for the creation of a normalized matrix to evaluate read accuracy and volume of operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the complete Friis Equation is solved for all possible orientations and polarizations to determine three-dimensional read accuracy, then measurement precision is improved, but device complexity and memory requirements increase significantly

Engineering Contradiction:

Improvethree-dimensional read accuracyVSAvoidcomputational complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the three-dimensional space into discrete angular positions (theta and phi angles) and polarization states. By dividing the continuous space into manageable discrete points, the system can evaluate read accuracy at each segment independently, reducing the overall computational complexity while maintaining measurement precision across the entire volume.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary calculations by pre-determining the maximum received power at each discrete spatial position and polarization combination using the Friis Equation. These pre-calculated power values are stored in a lookup table, allowing the system to quickly determine read accuracy without performing complete calculations during operation, thus reducing real-time computational complexity.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If the complete Friis Equation is solved for all possible orientations and polarizations to determine three-dimensional read accuracy, then measurement precision is improved, but memory requirements increase significantly

Engineering Contradiction:

Improvethree-dimensional read accuracyVSAvoidmemory requirements

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent segments the three-dimensional space into discrete angular positions (theta and phi angles) and polarization states. By dividing the continuous space into manageable discrete points, the system can evaluate read accuracy at each segment independently, reducing the overall computational complexity while maintaining measurement precision across the entire volume.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary calculations by pre-determining the maximum received power at each discrete spatial position and polarization combination using the Friis Equation. These pre-calculated power values are stored in a lookup table, allowing the system to quickly determine read accuracy without performing complete calculations during operation, thus reducing real-time computational complexity.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If maximum read range is calculated using simplified Friis Equation with maximum gain values, then ease of operation is improved, but measurement precision deteriorates

Engineering Contradiction:

Improvecalculation simplicityVSAvoidoperational volume information

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent applies partial action by calculating read accuracy at selected discrete angular positions and polarization states rather than continuously across all possible orientations. This selective sampling provides sufficient information about the operational volume without requiring complete evaluation of every possible configuration, thus maintaining ease of operation while improving measurement precision compared to the simplified maximum read range approach.

Inventive Principle:

Principle #16Partial or excessive action

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 significantly reduces computational complexity and memory requirements, enabling the determination of read accuracy and operational volume of RFID tags in three-dimensional space, providing a practical method for evaluating RFID system performance and comparing different tags based on their operational areas.

Implementation Method 1

The power at a receiving antenna, specifically an RFID tag, can be found using the Friis Equation... PT—transmit power... PR—received power

Methodology Applied

Scientific EffectElectromagnetic radiation: Electromagnetic Induction

Data Source

PatentUS7528696B2Determining the three-dimensional read accuracy of an RFID tag using a power scaling factor

Publication Date: 2009.05.05 UNIV OF PITTSBURGH OF THE COMMONWEALTH SYST OF HIGHER EDUCATION

AI summary

A method of generating a normalized matrix for use in determining one or more read accuracies of an RFID tag at selected points in space relative to a transmitter associated with the RFID tag. The method may further include using the normalized matrix to determine a particular read accuracy of the RFID tag at a particular point in space relative to the transmitter. Also, a method of generating a power scaling factor for determining the read accuracy of an RFID tag.