US 10,474,851 B2Granted

Systems and methods for collision avoidance in a multiple RFID interrogator environment

AssigneeSmartrac Technology Fletcher, Inc.

InventorKirk Greefkes

Life of this patent

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Abstract

A method for collision avoidance in a multi-reader environment comprising a plurality of Radio Frequency Identification (RFID) interrogators, the method comprises each of the plurality of interrogators entering a quiet state during which none of the interrogators transmits, each of the plurality of interrogators selecting a transmit time after the quiet period during which each of the interrogator will attempt to transmit, each of the plurality of interrogators monitoring their associated receive path, an interrogator of the plurality of interrogators transmitting an instruction during its selected transmit time indicating the beginning of a session when the interrogator does not detect data on its receive path prior to its select transmit time, the interrogator comparing its receive path to its transmit path when it transmits the instruction, the interrogator returning to the quiet state when the receive path does not match the transmit path, and the interrogator completing the session when the receive path matches the transmit path.

Claims17

Dependent claims

A radio frequency identification (RFID) interrogator disposed in a multiple-interrogator environment, comprising;

a transmit (Tx) circuit configured to transmit encoded data on a Tx path;
a receive (Rx) circuit configured to decode received data received via a Rx path;
a collision detection circuit configured to detect a data collision on one of the Tx path and the Rx path based on a comparison of the Rx path and the Tx path;
and
a processor coupled to the collision detection circuit, the Tx circuit, and the Rx circuit, and configured to
cause the RFID interrogator to enter a quiet state, the quiet state defining a predetermined time period in which the Tx circuit ceases transmission,
cause the Tx circuit to transmit a first message of the plurality of messages at a first time after expiration of the predetermined time period, if the collision detection circuit does not detect a data collision at or before the first time,
cause the RFID interrogator to return to the quiet state when the collision detection circuit detects a data collision at or before the first time,
selecting a second time at which the Tx circuit begins transmitting a second message of the plurality of messages the second time being after the first time;
cause the RFID interrogator to return to the quiet state when the collision detection circuit detects a data collision at or before the second time, and
cause the Tx circuit to transmit a remainder of the plurality of messages when the collision detection circuit does not detect a data collision at or before the second time.

8 more elements

A method for operating a radio frequency identification (RFID) interrogator disposed in a multiple-interrogator environment, the RFID interrogator having a transmit (Tx) circuit having a Tx path, a receive (Rx) circuit having a Rx path, and a collision detection circuit coupled to the Tx path and the Rx path and configured to detect a data collision on one of the Tx path and the Rx path based on a comparison of the Rx path and the Tx path, the method comprising:

causing, by a processor, the RFID interrogator to enter a quiet state for a predetermined time period during which the Tx circuit ceases transmission on the Tx path;
selecting, by the processor, a first time after the predetermined time period to transmit encoded data on the Tx path;
cause the Tx circuit to transmit a first message of the plurality of messages at a first time after expiration of the time period, if the collision detection circuit does not detect a data collision at or before the first time;
cause the RFID interrogator to return to the quiet state when the collision detection circuit detects a data collision at or before the first time,
cause the RFID interrogator to return to the quiet state when the collision detection circuit detects a data collision at or before a second time at which the Tx circuit begins transmitting a second message of the plurality of messages on the Tx path, the second time being after the first time;
and
cause the Tx circuit to transmit a remainder of the plurality of messages when the collision detection circuit does not detect a data collision at or before the second time.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 15/833,871Filed 6 Dec 2017 · continuation
Priority: 29 Jun 2007
Published: US 2018/0096176 A15 Apr 2018
Granted: 12 Nov 2019
Term ends: Not estimatedThe source records don’t support an estimate.

Classification6 codes

G06K 7/10019
Sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves: resolving collision on the communication channels…
G06K 7/0008
Methods or arrangements for sensing record carriers, e.g. for reading patterns: general problems related to the reading of electronic memory…
G06K 7/10356
Using at least one antenna particularly designed for interrogating the wireless record carriers: using a plurality of antennas, e.g.…
H04W 74/085
With collision treatment: collision avoidance

Family

Application60/947,110Us provisional application · filed 29 Jun 2007
Application12/163,643Parent of this continuation · filed 27 Jun 2008
Application14/704,727Parent of this continuation · filed 5 May 2015
US 9,035,748 B2Parent of this continuation · filed 19 May 2015
US 2018/0096176 A1Pre-grant publication · published 5 Apr 2018
US 9,846,794 B2Parent of this continuation
US 2009/0015382 A1Published application
US 2015/0235062 A1Published application
US 10,474,851 B2This patent

From the US filing history. Foreign family members aren’t listed.