RFID Reader Synchronization Sequence for Collision Recovery

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Solution Overview

Problem

RFID systems, particularly those following EPCGlobal Class 1 Gen 2 standards, face inefficiencies due to collisions between tags when trying to communicate with readers, as conventional anti-collision algorithms can only decode a single tag per slot, limiting reading efficiency to 36% in dense networks.

Innovation Solution

Embedding a synchronization sequence within the signal allows the reader to synchronize and calculate transmission characteristics, enabling the separation of payload information from collided signals and improving communication efficiency by allowing multiple tags to be identified per slot without altering the existing standards.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional Framed Slotted Aloha algorithm is used for anti-collision, then the system maintains compatibility with EPCGlobal Class 1 Gen 2 standards, but the reading efficiency is limited to 36% because only single tag replies can be decoded

Engineering Contradiction:

Improvereading efficiencyVSAvoidanti-collision algorithm complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent segments the signal structure by embedding a synchronization sequence between the first and second portions of the tag signal. This segmentation enables the reader to separately process synchronization detection and payload extraction, allowing collision recovery through channel estimation while maintaining standard compatibility.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The synchronization sequence is embedded in advance within the tag signal before transmission. This preliminary action enables the reader to perform channel estimation and calculate transmission characteristics before extracting payload information, facilitating collision resolution without requiring complex post-processing algorithms.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If collision recovery is implemented to increase reading efficiency, then multiple tags can be identified per slot, but the system requires advanced channel estimation techniques that are not compatible with existing standards

Engineering Contradiction:

Improvereading efficiencyVSAvoidcompatibility with EPCGlobal standards

Core Design Contradiction:

ProductivityVSAdaptability or versatility

Solution Approach 1:

The embedded synchronization sequence serves multiple functions: it enables synchronization detection, provides channel estimation data for collision recovery, and maintains signal structure compatibility with EPCGlobal Class 1 Gen 2 standards. This multi-functionality allows the system to achieve advanced collision recovery capabilities while remaining universally compatible.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The synchronization sequence acts as an intermediary element within the tag signal that carries dual purposes: it facilitates the technical function of channel estimation for collision recovery while preserving the overall signal format required by existing standards, thus mediating between advanced functionality and standard compatibility.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If the reader processes only single tag replies per slot, then the system implementation remains simple, but collided slots cannot be converted into successful slots

Engineering Contradiction:

Improvereading efficiencyVSAvoidreader processing simplicity

Core Design Contradiction:

ProductivityVSEase of operation

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces complex post-collision processing mechanics with a pre-embedded synchronization sequence that enables automatic channel estimation and transmission characteristic calculation. This substitution simplifies the reader's processing burden while enabling collision recovery functionality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP3091476B1Reader and tag

Publication Date: 2019.10.16 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV

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AI summary

A reader for wirelessly receiving a signal from a tag, the signal comprising a portion on a first side, a portion on a second side and a synchronization sequence to be detected between the first and the second side, wherein the portion on the first side, the synchronization sequence and the portion on the second side are serially arranged with each other, comprises a processor. The processor is configured for storing the received signal, for detecting the synchronization sequence in the received signal, for calculating a transmission characteristic between the tag and the reader, using the portion of the received signal on the first side and for extracting a payload information from the portion of the received signal on the second side, using the calculated transmission characteristic.