Adaptive RFID Interrogator Retransmission Wait Time
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Solution Overview
Problem
Mobile RFID interrogators face challenges in effectively managing collisions and synchronizing operations due to unpredictable positions and arrangements, leading to communication errors and inefficiencies in command retransmissions, especially in environments where hard-wired synchronization is not feasible.
Innovation Solution
An RFID interrogator with a collision diagnosis unit that analyzes received signals to identify collision types and a random wait time calculation mechanism to adaptively set retransmission times, allowing for situational command retransmissions and collision resolution without the need for channel sensing or synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If command retransmission is performed without adaptive wait time calculation, then communication continuity is maintained, but collision probability increases and communication efficiency deteriorates
Solution Approach 1:
The patent implements dynamic wait time adjustment by calculating adaptive retransmission wait times based on real-time collision detection results. Instead of using fixed wait times, the system dynamically modifies wait time parameters (c1, c2, c3) according to collision types and environmental conditions, allowing the retransmission strategy to adapt to changing communication environments and reduce collision probability while maintaining communication continuity
Solution Approach 2:
The patent employs feedback mechanisms where collision detection results from previous transmissions are used to adjust subsequent retransmission wait times. The system continuously monitors communication status, identifies collision types (interrogator-interrogator, interrogator-tag, tag-tag), and feeds this information back into the wait time calculation algorithm to optimize retransmission timing and improve communication efficiency
2Reliability
If hard-wired synchronization is used to coordinate interrogators, then collision avoidance is improved, but device mobility and ease of operation deteriorate
Solution Approach 1:
The patent replaces hard-wired mechanical synchronization connections with wireless collision detection and adaptive wait time calculation mechanisms. The system uses radio frequency communication to detect collisions and coordinate retransmissions without physical connections, enabling mobile interrogators to operate autonomously while maintaining collision avoidance capabilities through software-based coordination
Solution Approach 2:
Each mobile interrogator independently performs collision detection and calculates its own adaptive wait times without requiring external synchronization signals from other interrogators. The system enables self-service operation where interrogators autonomously adjust their retransmission timing based on detected collision patterns, eliminating the need for hard-wired synchronization while maintaining operational coordination
3Reliability
If Listen Before Talk (LBT) is implemented to prevent simultaneous activation, then collision probability is reduced, but device complexity and energy consumption increase
Solution Approach 1:
Instead of implementing full LBT mechanisms that require continuous channel sensing and complex synchronization protocols, the patent applies partial collision avoidance by using adaptive wait time calculation based on detected collision patterns. The system performs collision detection and adjustment only when needed, rather than continuously monitoring before each transmission, thereby reducing device complexity and energy consumption while still achieving collision probability reduction
4Device complexity
If fixed wait time parameters are used for retransmission, then device complexity is reduced, but adaptability to different collision scenarios deteriorates
Solution Approach 1:
The patent implements parameter changes by dynamically adjusting wait time parameters (c1, c2, c3) based on detected collision types and environmental conditions. The system modifies these parameters within defined ranges to adapt retransmission timing to different scenarios (interrogator-interrogator collisions, interrogator-tag collisions, tag-tag collisions), enhancing versatility without requiring complex device architecture
Data Source
AI summary
As an RFID interrogator calculating an adaptive retransmission wait time and a control method thereof, the RFID interrogator includes a collision diagnosis unit that analyzes data on a received signal received during a receive time in correspondence with a transmitted signal from an RF communication unit that can transmit and receive signal to and from one or more tag, verifies whether or not a collision occurs in the received signal, and diagnoses a collision type depending on an analysis result of the data on the received signal; a situational command retransmission portion that determines whether or not the command is retransmitted on the basis of the occurrence of the collision and the collision type received from the collision diagnosis unit; and a random wait time calculation portion that calculates a random wait time for retransmitting the command.