RFID Reader-Writer Error Handling via Time Slot Management
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Solution Overview
Problem
In RFID systems, when multiple unspecified tags are present in the range of a reader-writer's RF waves, response signals from tags can collide, leading to reading errors and non-read tags remaining undetected.
Innovation Solution
The RFID system includes a reader-writer that adds reading error information to subsequent commands and uses a tag circuit unit with a reading error detector to manage time slots and prevent erroneous completion flags, ensuring all tags are read by re-transmitting commands with error information until successful reading occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple RFID tags respond simultaneously to a reading command, then the reading process is fast, but response signals collide causing reading errors and non-read tags remain
Solution Approach 1:
The patent segments the reading process into multiple time slots, allowing tags to respond sequentially rather than simultaneously. The reader-writer transmits reading commands with different time slot assignments, and tags respond in their assigned slots, preventing signal collision while maintaining efficient batch processing
Solution Approach 2:
The patent implements a feedback mechanism where the reader-writer detects reading errors and re-transmits commands with adjusted parameters. When a reading error occurs, the system feedbacks by re-sending the reading command with modified time slot assignments or power levels to resolve the collision and successfully read all tags
2Reliability
If the reader-writer re-transmits reading commands to resolve errors, then reading accuracy improves, but processing time increases
Solution Approach 1:
The patent performs preliminary actions by pre-assigning time slots to tags before the actual reading occurs. The reader-writer transmits reading commands that include time slot information in advance, allowing tags to prepare their responses and avoiding the need for multiple error-prone re-transmissions
Solution Approach 2:
The patent uses periodic time slot assignments where tags are scheduled to respond at regular intervals. This periodic structure organizes the reading process into manageable cycles, reducing random collisions and enabling efficient error recovery through predictable re-transmission patterns
3Reliability
If time slots are increased to reduce collision probability, then reading accuracy improves, but system complexity increases
Solution Approach 1:
The patent implements dynamic time slot management where the number and assignment of time slots are adjusted based on the number of tags detected and collision patterns. The system starts with a baseline number of slots and dynamically increases or decreases them based on feedback from reading operations, optimizing performance without requiring complex fixed-slot configurations
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 effectively prevents non-read tags from remaining and reduces processing time by efficiently managing time slots and error handling, enhancing reading efficiency even when new tags are added to the communication area.
Implementation Method 1
a reader-writer (3) reading identification information (25b) from a plurality of RFID tags (2) via a transceiver unit (31) and an antenna (3a)
Data Source
AI summary
A radio frequency identification (RFID) system includes a plurality of RFID tags and a reader-writer. Each of the plurality of RFID tags has a tag antenna and a tag circuit that stores identification information. The reader-writer includes a first transceiver that reads the identification information of the plurality of RFID tags using an antenna. In this regard, the first transceiver transmits a reading command via the antenna for reading the identification information of the plurality of RFID tags. When the first transceiver does not read the identification information from one of the plurality of RFID tags due to an occurrence of a reading error in the first transceiver, the reader-writer adds reading error information, which indicates the occurrence of the reading error, to the next reading command to be transmitted from the first transceiver via the antenna.