RFID Reader Coordination to Avoid LBT Waiting and Tag Data Loss

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Solution Overview

Problem

In logistics and inventory management systems using UHF band RFID readers, communication collisions occur when multiple readers approach each other, leading to one entering a Listen Before Talk (LBT) waiting state and preventing the acquisition of tag information.

Innovation Solution

A communication apparatus with an approach detection unit that uses a method other than RFID to detect proximity to another reader and receive tag reading results from that reader, and an arbitration processing unit to arbitrate tag reading execution between readers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the RFID reader apparatus performs carrier sense function to avoid communication collision, then communication reliability is improved, but response time deteriorates due to LBT waiting state

Engineering Contradiction:

Improvecommunication reliabilityVSAvoidresponse time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system performs preliminary carrier sense for all channels to identify free channels in advance, storing this information for future use. This preliminary action allows the RFID reader to skip the carrier sense step in subsequent operations, eliminating LBT waiting time while maintaining communication reliability through pre-identified safe channels.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If the RFID reader apparatus uses the same channel as another RFID reader due to limited free channels, then device complexity is reduced, but communication collision increases

Engineering Contradiction:

Improvechannel management complexityVSAvoidcommunication collision

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The system introduces a predetermined communication method (ultrasonic or optical communication) as an intermediary channel between RFID readers. This alternative communication path allows readers to exchange information about tag reading status without using the RFID frequency band, enabling collision-free operation even when RFID channels are shared, while maintaining simple channel management.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the RFID reader apparatus enters LBT waiting state when approaching another reader, then communication collision is avoided, but information acquisition capability deteriorates

Engineering Contradiction:

Improvecollision avoidanceVSAvoidinformation acquisition capability

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The system uses ultrasonic or optical communication as an intermediary to transmit tag reading results between approaching RFID readers. When one reader enters LBT waiting state, the other reader can still acquire tag information through this intermediary communication channel, maintaining information acquisition capability while ensuring collision avoidance through the predetermined communication method.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12524633B2Communication apparatus that communicates tag information with another communication apparatus

Publication Date: 2026.01.13 CANON KK

AI summary

A communication apparatus capable of executing reading of an RFID tag, the communication apparatus includes an approach detection unit that detects, by using a predetermined communication method, approach of the communication apparatus to another communication apparatus capable of executing reading of the RFID tag, and a reception unit that receives, by using the predetermined communication method, information of the RFID tag read by the other communication apparatus from the other communication apparatus.