RFID Tags With Orthogonal Modulation for Multi-Tag Reading
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Solution Overview
Problem
Current RFID technologies face limitations in communication distance and efficiency due to inductive coupling, which restricts data transfer speed and range, making it difficult to read multiple tags simultaneously within a given period.
Innovation Solution
Employing orthogonal modulation techniques, such as OFDM, and using multiple antennas for both RFID tags and readers to increase communication range and robustness, allowing for simultaneous reading of multiple tags through MIMO systems and parallel transmission over orthogonal channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If inductive coupling is used for energy harvesting and communication, then communication speed can be increased, but communication distance is limited to a few inches
Solution Approach 1:
The patent transitions from inductive coupling (near-field) to electromagnetic wave propagation (far-field) by changing the communication dimension. The RFID tag and reader use electromagnetic waves operating at ISM bands (e.g., 2.4 GHz) to achieve long-distance communication while maintaining high data transfer rates, effectively moving from a near-field inductive coupling model to a far-field electromagnetic radiation model.
2Productivity
If traditional RFID communication methods are used, then device complexity is kept simple, but the ability to read multiple tags simultaneously is limited
Solution Approach 1:
The patent segments the communication channel into multiple orthogonal channels using OFDM technology. Each subcarrier in the OFDM spectrum can independently carry data from different tags, allowing the reader to simultaneously receive and decode multiple tags' information through frequency-division multiplexing. This segmentation of the spectral resource enables parallel communication with multiple tags.
Solution Approach 2:
The patent introduces frequency domain multiplexing as an additional dimension for communication. By using orthogonal frequency division multiplexing (OFDM), the system creates multiple independent communication channels in the frequency domain, allowing simultaneous transmission from multiple tags without interference. This adds a spectral dimension to the traditional time-space communication model.
3Speed
If communication time between each tag and reader is reduced, then data transfer speed increases, but the time available for reading multiple tags decreases
Solution Approach 1:
The patent enables continuous useful action by implementing parallel communication channels through OFDM. While one tag is being read on one frequency subcarrier, other tags can simultaneously transmit their data on different subcarriers. This eliminates the sequential reading bottleneck and maintains continuous data collection across multiple tags without idle time between tag readings.
Solution Approach 2:
The patent merges multiple tag communications into a single received signal by combining transmissions from multiple tags across orthogonal frequency channels. The reader receives a composite signal containing data from multiple tags simultaneously and uses correlation techniques to separate and decode each tag's information, effectively merging multiple communication streams into one reception process.
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 significantly enhances communication range and speed, enabling the efficient reading of multiple tags within a shorter time frame, thereby improving data collection capabilities in RFID systems.
Implementation Method 1
The tag and reader use electromagnetic waves to communicate
Data Source
AI summary
An apparatus for use in an RFID data collection system includes an antenna portion for wirelessly exchanging signals and a memory portion for storing RFID data. A signal processing portion is coupled among the antenna portion and the memory portion. The signal processing portion is configured to receive RFID data and to at least encode or decode the received RFID data via at least two orthogonal modulation signals. Other configurations are also disclosed.