Synchronized RFID Reader Scan Timing for Dock Door Tag Confusion
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Solution Overview
Problem
In RFID tag communication systems using the UHF band, the larger communication area leads to tag confusion and reading failures due to unsynchronized scan timing between RFID reader/writers installed on both sides of a dock door, causing signal saturation and demodulation issues.
Innovation Solution
A tag communication apparatus with a phased array antenna that synchronizes scan timing with another tag communication apparatus by extracting synchronizing information from received radio waves, allowing for synchronized transmission direction changes to prevent tag confusion and improve detection accuracy of moving RFID tags.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If two RFID reader/writers are installed on both sides of the dock door to cover the communication area, then the communication coverage is improved, but tag confusion and reading failures occur due to unsynchronized scan timing
Solution Approach 1:
The patent combines the functions of multiple RFID reader/writers into a coordinated system where they operate as a unified entity. The synchronization mechanism merges their scan operations timing-wise, allowing them to function together rather than independently, thus preventing tag confusion while maintaining comprehensive coverage.
Solution Approach 2:
The system implements feedback through synchronization signals exchanged between opposing reader/writers. Each device adjusts its scan timing based on feedback from the other, creating a closed-loop control system that maintains synchronized operation and prevents reading failures.
2Reliability
If the scan timing is synchronized between opposing RFID reader/writers, then tag confusion is prevented, but additional devices for synchronization are required
Solution Approach 1:
The patent introduces a synchronization signal as an intermediary mechanism between opposing reader/writers. This mediator carries timing information that allows both devices to coordinate their scan operations without requiring complex direct control connections, simplifying the overall system architecture.
Solution Approach 2:
The synchronization signal serves multiple functions: it coordinates scan timing, prevents tag confusion, and enables the system to operate as an integrated unit. This multi-functional approach reduces the need for separate dedicated synchronization hardware.
3Reliability
If the distance between opposing RFID reader/writers is increased to 10 m or more to prevent signal saturation, then receiver saturation is avoided, but the installation becomes difficult in typical dock door environments
Solution Approach 1:
The patent employs periodic scanning actions with synchronized timing between opposing reader/writers. By coordinating their operational cycles, they can operate at closer distances without continuous signal interference, as each device activates in alternating or synchronized periods rather than continuously overlapping.
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 synchronization of scan timing between RFID reader/writers prevents tag confusion and signal saturation, enabling accurate demodulation of weak RFID tag signals and improving the detection of moving objects within the communication area.
Implementation Method 1
a phased array antenna that synchronizes scan timing with another tag communication apparatus by extracting synchronizing information from received radio waves
Implementation Method 2
a receiver to receive second radio waves transmitted from the second tag communication apparatus
Data Source
AI summary
A first tag communication apparatus is adapted to perform radio communications with a second tag communication apparatus and an RFID tag provided on a moving object. A controller is operable to cause an antenna to transmit first radio waves while changing a first direction that the first radio waves are transmitted. A receiver is operable to receive a second radio waves transmitted from the second tag communication apparatus. An extractor is operable to extract, from the second radio waves, synchronizing information indicative of a timing that the second tag communication apparatus changes a second direction that the second radio waves are transmitted therefrom. A synchronizer is operable to synchronize a timing that the controller changes the first direction with the timing that the second tag communication apparatus changes the second direction, based on the synchronizing information.