RF Tag Collision Management via Probability Queries
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Solution Overview
Problem
Current radio frequency (RF) Tags require significant logic to handle interface protocols and anti-collision protocols, leading to increased cost and complexity, and existing solutions for avoiding collisions when reading multiple RF Tags are inefficient.
Innovation Solution
The system employs a method where Tags are queried with a probability parameter, allowing them to randomly decide whether to reply, and the Reader adjusts the probability parameter to manage collisions, using state flags to differentiate responses and reduce protocol complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the range of wireless Tags is extended so that it is not necessary to bring each Tag close to a Reader for reading, then the reading distance is improved, but many Tags will be within the range of the interrogating system so that their replies may corrupt each other
Solution Approach 1:
The Reader performs preliminary actions by sending a query command with probability parameter Q and state flag A/B before Tags reply. This preliminary action allows the Reader to control the reading process and manage multiple Tags systematically, preventing reply corruption while maintaining extended reading distance
Solution Approach 2:
The probability parameter Q and state flag (A/B) act as intermediaries between the Reader and multiple Tags. These intermediaries enable the Reader to regulate Tag responses, ensuring that only Tags in the specified state reply while controlling the probability of response, thus preventing reply corruption in extended range scenarios
2Adaptability or versatility
If current integrated circuits that are used in RF Tags include logic to handle interface protocols and anti-collision protocols, then the protocol handling capability is improved, but the size of the integrated circuit increases
Solution Approach 1:
The patent extracts the complex anti-collision logic from the Tag's integrated circuit and relocates it to the Reader. The Tag only needs to implement simple state machine logic (states A and B) and basic probability-based response, while the Reader handles the complex probability parameter adjustment and collision management, significantly reducing Tag IC size
Solution Approach 2:
The patent uses a simplified copy of the protocol handling logic in the Tag, implementing only the essential state machine (states A and B) and probability-based response mechanism. The full protocol intelligence is copied to the Reader, allowing the Tag to remain simple while maintaining protocol handling capability through the Reader's control
Data Source
AI summary
Embodiments of the present invention include systems with Readers and Tags in which a Reader queries the Tags with a parameter that includes a level of probability of reply according to which the Tags individually and randomly decide whether or not to reply. In one embodiment, the Tags can switch between two states: A and B. The query command also specifies a state (A or B) so that only the Tags in the specified state can reply. After successfully sending the Tag identification data from a Tag to the Reader, the Tag switches to the other state from the specified state. In one embodiment, the operations about the two states are symmetric. In one embodiment, the Tags can remember the parameters used in a query so that a short form of query command can be used to repeat the query with the same query parameters.