RFID Modem Layer Local Tag Filtering
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Solution Overview
Problem
In dynamic RFID environments, existing systems face inefficiencies in processing large numbers of RFID tags due to the need to transmit responses to a remote processor and wait for decisions, leading to valuable processing time being lost as tags enter and leave the reader's field of view with varying reliability.
Innovation Solution
An RFID system architecture with layers such as a modem layer, application processor layer, and server layer that allows for preselect and post-select operations to filter tags based on criteria, reducing the need to process all tags by the full reader system, and optimizing transmit power levels for inventorying and access operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If tag responses are transmitted to a remote processor for processing, then centralized control and decision-making are achieved, but processing time is lost due to transmission delays and waiting for decisions
Solution Approach 1:
The system segments processing tasks between two layers: the modem layer handles initial response filtering and preselect operations, while the remote processor handles postselect operations and exception handling. This segmentation allows time-critical filtering to occur locally without transmission delays, while maintaining centralized control for complex decisions.
Solution Approach 2:
The modem layer performs preliminary filtering actions by evaluating preselect criteria against tag responses before transmitting to the remote processor. This preliminary action eliminates unnecessary transmissions and reduces the workload on the remote processor, achieving both centralized control and time efficiency.
2Productivity
If all tag responses are processed by the full reader system, then comprehensive processing is achieved, but processing speed decreases due to the large volume of tags
Solution Approach 1:
The system applies partial action by having the modem layer perform only preselect filtering on tag responses, rather than complete processing. This partial processing at the modem layer reduces the volume of data requiring full system processing, thereby increasing overall processing speed while maintaining necessary complexity for comprehensive tag evaluation.
3Reliability
If transmit power is increased for inventorying operations, then reading range and reliability are improved, but energy consumption increases
Solution Approach 1:
The system dynamically adjusts transmit power levels based on operational requirements. Higher power is used during inventorying operations to ensure reliable reading of multiple tags, while lower power is used during access operations when only specific tags need to be read. This dynamic adjustment maintains reading reliability while optimizing energy consumption across different operational phases.
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 enables faster inventorying and access operations by filtering tags locally, reducing processing delays and improving efficiency by only sending exceptions to higher layers, while optimizing power usage for specific operations.
Implementation Method 1
A tag that senses the interrogating RF wave responds by transmitting back another RF wave. The tag generates the transmitted back RF wave either originally, or by reflecting back a portion of the interrogating RF wave in a process known as backscatter.
Data Source
AI summary
Radio frequency identification (RFID) tags are selected for inventorying using a combination of preselect and/or post select criteria. The selection commands can be for selecting according to a tag memory content, by invoking the mask address or by comparing other tag characteristics. Selection criteria can be determined locally at a modem block of a reader or provided to the modem block by higher layers of the reader. Tags meeting the selection criteria are reported to the higher layers for further actions. Some tags may be held while waiting for instructions from the higher layer block(s). The instructions may involve one or more access operations, which may be performed using a higher transmit power than other operations.