Systems and methods for synchronizing a plurality of RFID interrogators in a theatre of operation
First Claim
1. A radio frequency identification (RFID) interrogation system, comprising:
- multiple RFID interrogators, wherein each of the multiple RFID interrogators is configured to transmit data to surrounding RFID tags, and wherein the multiple RFID interrogators includes a first RFID interrogator, the first RFID interrogator is configured to;
transmit a portion of data to nearby RFID tags in a first half of a first frame;
wait a time period for a second half of the first frame to start;
upon the start of the second half of the first frame, detect any interference from another RFID interrogator among the multiple RFID interrogators;
andif an interference is detected from another RFID interrogator among the multiple RFID interrogators, determine if data is expected from a nearby RFID tag, and if no data is expected, adjust a timing of a start of a second frame to coincide with the start of a frame of the another RFID interrogator;
andif data is expected, select a random number of frames to wait to receive the expected data.
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Accused Products
Abstract
RFID tags are used for many purpose including tracking. RFID interrogators are used to retrieve information from tags. In many applications, a plurality of RFID interrogators are required. Synchronization between interrogators in the same theatre of operation is critical to ensure that their broadcasts do not interfere with each other. In fixed RFID interrogator applications, RFID interrogators can be wired together allowing a channel to synchronize the transmissions of the RFID interrogators. Methods described herein can ensure that synchronization is maintained in the event of the failure of a synchronizing master. Furthermore, additional methods for synchronizing RFID interrogators in wireless applications are described allowing synchronization in the absence of wired connections between interrogators.
17 Citations
20 Claims
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1. A radio frequency identification (RFID) interrogation system, comprising:
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multiple RFID interrogators, wherein each of the multiple RFID interrogators is configured to transmit data to surrounding RFID tags, and wherein the multiple RFID interrogators includes a first RFID interrogator, the first RFID interrogator is configured to; transmit a portion of data to nearby RFID tags in a first half of a first frame; wait a time period for a second half of the first frame to start; upon the start of the second half of the first frame, detect any interference from another RFID interrogator among the multiple RFID interrogators; and if an interference is detected from another RFID interrogator among the multiple RFID interrogators, determine if data is expected from a nearby RFID tag, and if no data is expected, adjust a timing of a start of a second frame to coincide with the start of a frame of the another RFID interrogator; and if data is expected, select a random number of frames to wait to receive the expected data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for operating a first radio frequency identification (RFID) interrogator among multiple RFID interrogators while avoiding interferences with other RFID interrogators among the multiple RFID interrogators, comprising:
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transmitting, by the first RFID interrogator a portion of data to nearby RFID tags in a first half of a first frame; waiting a time period for a second half of the first frame to start; upon the start of the second half of the first frame, detecting any interference from another RFID interrogator among the multiple RFID interrogators; and if an interference is detected from another RFID interrogator among the multiple RFID interrogators, determining if data is expected from a nearby RFID tag, and if no data is expected, adjusting a timing of a start of a second frame to coincide with the start of a frame of the another RFID interrogator; and if data is expected, selecting a random number of frames to wait to receive the expected data. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification