RFID Tag Backscatter Timing Adjustment for Accurate Link Periods

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Solution Overview

Problem

Existing RFID systems face inaccuracies in determining backscatter parameters due to limitations in current division techniques, leading to errors in calculating the backscatter link period, which affects the reliability of data transmission and identification processes.

Innovation Solution

The implementation of an adjustment mechanism in the RFID tag's processing circuitry to refine the division process by adding or applying adjustments before or after dividing the TRCAL.NO by the divide ratio, thereby improving the accuracy of backscatter link period calculation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If current division techniques are used to calculate backscatter link period, then the calculation process is simple, but the accuracy of backscatter parameter determination deteriorates

Engineering Contradiction:

Improveaccuracy of backscatter link period calculationVSAvoidcomplexity of processing circuitry

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary adjustment value that mediates between the simple division operation and the accurate backscatter link period calculation. This adjustment value compensates for errors introduced by truncating least significant bits, thereby improving measurement precision without requiring complete redesign of the division mechanism.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the division operation by introducing an adjustable parameter (the adjustment value) that can be varied to compensate for quantization errors. By changing parameters in the calculation process rather than the fundamental division algorithm, the system achieves higher accuracy while maintaining operational simplicity.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If least significant bits are truncated to simplify division, then the processing speed increases, but the error in backscatter link period determination increases

Engineering Contradiction:

Improveprocessing speed of division operationVSAvoidaccuracy of backscatter parameter

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent converts the harmful effect of truncating least significant bits (which causes quantization error) into a beneficial process by calculating a specific adjustment value that compensates for this truncation. The error introduced by simplification is systematically corrected, turning the simplified division process into an accurate calculation method.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent performs preliminary calculation of the adjustment value based on the truncated bits before finalizing the backscatter link period. This preliminary action prepares the compensation data in advance, allowing the main division operation to proceed quickly while the correction is already prepared, thus maintaining both speed and accuracy.

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If adjustment mechanism is added to refine division process, then the accuracy of backscatter link period calculation improves, but the device complexity increases

Engineering Contradiction:

Improveaccuracy of backscatter link periodVSAvoidcomplexity of processing circuitry

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the calculation process into distinct functional blocks: a division unit that performs the main division operation, a truncation unit that removes least significant bits, and an adjustment unit that calculates and applies the correction value. This segmentation allows each component to be optimized independently while working together to achieve high accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies partial correction by adjusting only the specific portion of the calculation that is affected by truncation error, rather than redoing the entire division process. This partial action approach adds minimal complexity to the adjustment mechanism while achieving the necessary precision improvement.

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 reduces the mean error in determining the backscatter link period, enhancing the reliability and accuracy of data transmission and identification processes in RFID systems.

Implementation Method 1

A tag that senses the interrogating RF wave responds by transmitting back another RF wave. The tag generates the transmitted back RF wave either originally, or by reflecting back a portion of the interrogating RF wave in a process known as backscatter.

Methodology Applied

Scientific EffectBackscatter: Reflection

Data Source

PatentUS7472835B2RFID system components implementing adjusted backscatter calculations and methods

Publication Date: 2009.01.06 IMPINJ

AI summary

RFID system components, such as readers and tags, communicate by a reader transmitting waveforms that encode a calibration symbol and a divide ratio. Tags include a processor to determine a backscatter link period result by dividing a count value representing the calibration symbol by the divide ratio and adding an adjustment. Tags modulate a backscatter waveform that includes symbols using a link period determined from the result.