Dynamic Link Frequency Adjustment for RFID Passive Label Reading
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Solution Overview
Problem
In RFID systems using passive labels, the reverse link performance is often poor due to environmental interference and frequency congestion, leading to unsuccessful information retrieval and reduced reading rates, especially in multipath environments and dense reader settings.
Innovation Solution
A method where a reader conducts an initial query at a high link frequency and subsequent queries at progressively lower frequencies for labels that failed to respond, improving the reverse link performance and reducing congestion by adjusting the link frequency used in each query.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If repeated queries are conducted at a fixed link frequency to increase reading rate, then the reading rate improves, but the reverse link performance cannot be actively improved and overall reading time increases
Solution Approach 1:
The patent applies dynamics by making the link frequency adjustable rather than fixed. The reader dynamically changes the link frequency for subsequent queries based on whether labels successfully returned information, allowing the system to adapt to varying reverse link conditions and actively improve performance while managing reading time efficiently
Solution Approach 2:
The patent changes the link frequency parameter to resolve the contradiction. By varying the link frequency in subsequent queries when labels fail to respond, the system actively improves reverse link performance without relying solely on repeated readings at the same frequency, thereby balancing reading rate and overall reading time
2Ease of operation
If multiple readers use the same reverse link frequency to simplify operation, then ease of operation is improved, but frequency congestion occurs causing poor reverse link performance
Solution Approach 1:
The patent applies local quality by allowing different readers to use different link frequencies. Instead of a uniform frequency across all readers, each reader can select and use a specific link frequency locally, reducing frequency congestion and improving reverse link reliability while maintaining operational simplicity through automatic frequency management
Solution Approach 2:
The system dynamically assigns and adjusts link frequencies for different readers and queries. This dynamic approach allows the system to avoid frequency congestion automatically while maintaining ease of operation, as the frequency management is handled autonomously by the readers based on the protocol specifications
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 increases the successful reading rate of passive labels by enhancing the reverse link sensitivity and avoiding long-term frequency congestion, thereby balancing overall reading time and performance.
Implementation Method 1
Without a battery, a passive label needs to obtain energy from the RF wave emitted by the reader for power supply
Implementation Method 2
the label returns information related to the label to the reader at the continuous-wave frequency through backscattering
Data Source
Figure 1~2
Figure 3~4
AI summary
The present invention provides a method to conduct a label query in a radio frequency identification system (41). Wherein, a query process conducted by a reader (30) for a group of passive labels (40) comprises a first query (1) and a subsequent query (2). The link frequency (LF2) used by a reverse link from label (40) to reader (30) in the subsequent query (2) is smaller than that (LF1) used by the reverse link in the first query (1). With the method of the present invention, the reverse link performance of passive label radio frequency identification system is improved, and the success rate of reading is increased. The invention further provides a reader (30) to implement the method.