Synchronization of devices in a RFID communications environment

• US 20100277286A1
• Filed: 05/01/2009
• Published: 11/04/2010
• Est. Priority Date: 05/01/2009
• Status: Active Grant

• Current Assignee: L-3 Communications Integrated Systems LP (L3Harris Technologies, Inc.)
• Original Assignee: L-3 Communications Integrated Systems LP (L3Harris Technologies, Inc.)
• Inventors: Brown, Jonathan E., Burkart, Scott M.
• Granted Patent: US 8,456,282 B2
• Time in Patent Office: Days
• US Class Current: 340/10.34
• CPC Class Codes: G06K 19/0701 at least one of the integrated circuit chips comprising an arrangement for power management
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card

Abstract

An adaptive wakeup methodology may be implemented to allow an radio frequency identification (RFID) tag to stay synchronized with periodic radio frequency (RF) interrogator polling signal while at the same time optimizing power consumption. A receiver (or transceiver) component of a RFID tag may only be operated when an interrogator polling signal is expected, and in a manner that reduces the amount of time between when the receiver or transceiver is turned on and when the interrogator polling signal is received (i.e., the receive buffer time). At other times, the RFID tag may be placed in a low power consumption sleep state. The amount of time that the RFID tag spends in such a low power sleep state before waking and receiving the following interrogator polling signal may also be optionally adjusted, e.g., to fit characteristics of a given situation and/or to re-synchronize a given aRFID tag with first band transmissions from an aRFIDI.

Claims

1. A method of operating a radio frequency identification (RFID) tag within a radio frequency identification (RFID) communication environment, comprising:

providing at least one RFID tag configured to receive periodic first band RF signal interrogator polling signals and configured to transmit second band RF signal response signals in response thereto, the first band being a multiple channel-based frequency band and the second band being a non-channel based frequency band; and

repeatedly and alternately performing the following two steps;

operating the RFID tag in a timed low power sleep mode for a predefined sleep time during which the RFID tag does not listen for transmitted first band RF signal interrogator polling signals, and

then waking the RFID tag to operate in a timed powered up listening mode for a predefined tag listening time during which the RFID tag actively listens for transmitted first band RF signal interrogator polling signals; and

wherein the method further comprises dynamically adjusting the length of the predefined sleep time before again waking the RFID tag to the listening mode.

2. The method of claim 1, further comprising dynamically adjusting the length of the predefined sleep time before again waking the RFID tag to listening mode based upon at least one of the time of receipt of a periodic interrogator polling signal during the listening mode, the non-receipt of a periodic polling signal during the listening mode, or a combination thereof.

3. The method of claim 1, wherein the method further comprises dynamically adjusting the length of the predefined sleep time in at least one of the following manners:

receiving a periodic interrogator polling signal at the RFID tag at a given receipt time while the RFID tag is operating in the listening mode and increasing or decreasing the length of the predefined sleep time based on the given receipt time of the interrogator polling signal as necessary to maintain a predefined alignment time between the start time of the listening mode and the given receipt time of the latest periodic interrogator polling signal,

not receiving an interrogator polling signal at the RFID tag while the RFID tag is operating in the listening mode and decreasing the length of the predefined sleep time by an incremental amount of time before again operating the RFID tag in listening mode, or

a combination thereof.

4. The method of claim 1, wherein the method further comprises dynamically adjusting the length of the predefined sleep time to maintain a predefined receive buffer time;

wherein the predefined receive buffer time represents the latest time elapsed between the time of waking the RFID tag to operate in a timed powered up listening mode and the time of receipt of a first interrogator packet thereafter.

5. The method of claim 1, further comprising operating the RFID tag in a synchronized state with periodic interrogator signals by repeatedly and alternately performing the following steps:

operating the RFID tag in a timed synchronized low power sleep mode for a predefined synchronized sleep time during which the RFID tag does not listen for transmitted first band RF signal interrogator polling signals;

then waking the RFID tag to operate in a timed powered up synchronized listening mode for a predefined synchronized tag listening time during which the RFID tag actively listens for transmitted first band RF signal interrogator polling signals;

wherein the method further comprises performing the following steps if an interrogator polling signal is received during a given synchronized listening mode;

processing the latest received interrogator polling signal,

performing one or more tag processing operations,

increasing or decreasing the length of the predefined synchronized sleep time based on the given receipt time of the interrogator polling signal as necessary to maintain a predefined alignment time between the start time of the synchronized listening mode and the given receipt time of the periodic interrogator polling signal, and

returning the RFID tag to the timed synchronized low power sleep mode for the predefined synchronized sleep time; and

wherein the method further comprises performing the following steps if an interrogator polling signal is not received during a given synchronized listening mode;

decreasing the length of the predefined synchronized sleep time by an incremental amount of time,

performing one or more tag processing operations, and

returning the RFID tag to the timed synchronized low power sleep mode for the predefined synchronized sleep time if the number of consecutive times that an interrogator polling signal has not been received is less than a predefined threshold, or operating the RFID tag in an non-synchronized state with any periodic interrogator polling signals if the number of consecutive times that an interrogator polling signal has not been received is greater than a predefined threshold.

6. The method of claim 5, wherein the duration of the predefined synchronized tag sleep time is less than a predefined value of the frequency of the interrogator polling signals.

7. The method of claim 6, wherein the duration of the predefined synchronized tag sleep time is substantially equal to a predefined value of the frequency of the interrogator polling signals less a predefined receive buffer value and less the time for signal and tag processing operations.

8. The method of claim 5, wherein operating the RFID tag in an non-synchronized state with any periodic interrogator polling signals comprises repeatedly and alternately performing the following steps:

operating the RFID tag in a timed non-synchronized low power sleep mode for a predefined non-synchronized sleep time during which the RFID tag does not listen for transmitted first band RF signal interrogator polling signals;

then waking up the RFID tag to perform one or more tag processing operations;

then returning the RFID tag to the timed non-synchronized low power sleep mode for the predefined non-synchronized sleep time if the number of immediately previous consecutive sleep times is less than a predefined threshold, or operating the RFID tag in a timed powered up non-synchronized listening mode for a predefined non-synchronized tag listening time during which the RFID tag actively listens for transmitted first band RF signal interrogator polling signals if the number of immediately previous consecutive sleep times is greater than or equal to a predefined threshold.

9. The method of claim 8, wherein the duration of the predefined non-synchronized tag listening time is greater than or equal to a predefined value of the frequency of the interrogator polling signals.

10. The method of claim 8, further comprising then again operating the RFID tag in the synchronized state upon receipt of a periodic interrogator polling signal during the non-synchronized tag listening time of the non-synchronized listening mode.

11. The method of claim 1, wherein the first band is a narrow band frequency modulation (NBFM) frequency band;

and wherein the second band is an ultra-wideband (UWB) frequency band.

12. A frequency identification (RFID) tag system, comprising:

first band receiver or transceiver circuitry configured to receive periodic first band RF signal interrogator polling signals and second band transmitter circuitry configured to transmit second band RF signal response signals in response thereto, the first band being a multiple channel-based frequency band and the second band being a non-channel based frequency band; and

at least one processing device to repeatedly and alternately perform the following two steps;

operate the circuitry of the RFID tag in a timed low power sleep mode for a predefined sleep time during which the first band receiver or transceiver circuitry does not listen for transmitted first band RF signal interrogator polling signals,

then wake up circuitry of the RFID tag to operate in a timed powered up listening mode for a predefined tag listening time during which the first band receiver or transceiver circuitry actively listens for transmitted first band RF signal interrogator polling signals, and

dynamically adjust the length of the predefined sleep time before again waking circuitry of the RFID tag to the listening mode.

13. The system of claim 12, wherein the at least one processing device is further configured to dynamically adjust the length of the predefined sleep time before again waking the first band receiver or transceiver circuitry to listening mode based upon at least one of the time of receipt of a periodic interrogator polling signal during the listening mode, the non-receipt of a periodic polling signal during the listening mode, or a combination thereof.

14. The system of claim 12, wherein the at least one processing device is further configured to dynamically adjust the length of the predefined sleep time in at least one of the following manners:

increasing or decreasing the length of the predefined sleep time based on the given receipt time of the interrogator polling signal while the RFID tag is operating in the listening mode as necessary to maintain a predefined alignment time between the start time of the listening mode and the given receipt time of the latest periodic interrogator polling signal,

decreasing the length of the predefined sleep time by an incremental amount of time before again operating the RFID tag in listening mode upon not receiving an interrogator polling signal at the RFID tag while the RFID tag is operating in the listening mode, or

a combination thereof.

15. The system of claim 12, wherein the at least one processing device is further configured to dynamically adjust the length of the predefined sleep time to maintain a predefined receive buffer time;

wherein the predefined receive buffer time represents the latest time elapsed between the time of waking the first band receiver or transceiver circuitry of the RFID tag to operate in a timed powered up listening mode and the time of receipt of a first interrogator packet thereafter.

16. The system of claim 12, wherein the at least one processing device is further configured to operate the RFID tag in a synchronized state with periodic interrogator signals by repeatedly and alternately performing the following steps:

operating circuitry of the RFID tag in a timed synchronized low power sleep mode for a predefined synchronized sleep time during which the first band receiver or transceiver circuitry does not listen for transmitted first band RF signal interrogator polling signals;

then waking the circuitry of the RFID tag to operate in a timed powered up synchronized listening mode for a predefined synchronized tag listening time during which the first band receiver or transceiver circuitry actively listens for transmitted first band RF signal interrogator polling signals;

performing the following steps if an interrogator polling signal is received during a given synchronized listening mode;

processing the latest received interrogator polling signal,

performing one or more tag processing operations,

increasing or decreasing the length of the predefined synchronized sleep time based on the given receipt time of the interrogator polling signal as necessary to maintain a predefined alignment time between the start time of the synchronized listening mode and the given receipt time of the periodic interrogator polling signal, and

returning the RFID tag to the timed synchronized low power sleep mode for the predefined synchronized sleep time; and

performing the following steps if an interrogator polling signal is not received during a given synchronized listening mode;

decreasing the length of the predefined synchronized sleep time by an incremental amount of time,

performing one or more tag processing operations, and

returning circuitry of the RFID tag to the timed synchronized low power sleep mode for the predefined synchronized sleep time if the number of consecutive times that an interrogator polling signal has not been received is less than a predefined threshold, or operating the RFID tag in a non-synchronized state with any periodic interrogator polling signals if the number of consecutive times that an interrogator polling signal has not been received is greater than a predefined threshold.

17. The system of claim 16, wherein the duration of the predefined synchronized tag sleep time is less than a predefined value of the frequency of the interrogator polling signals.

18. The system of claim 17, wherein the duration of the predefined synchronized tag sleep time is substantially equal to a predefined value of the frequency of the interrogator polling signals less a predefined receive buffer value and less the time for signal and tag processing operations.

19. The system of claim 16, wherein the at least one processing device is further configured to operate the RFID tag in a non-synchronized state with any periodic interrogator polling signals comprises repeatedly and alternately performing the following steps:

operating circuitry of the RFID tag in a timed non-synchronized low power sleep mode for a predefined non-synchronized sleep time during which the first band receiver or transceiver circuitry does not listen for transmitted first band RF signal interrogator polling signals;

then waking circuitry of the RFID tag to perform one or more tag processing operations;

then returning circuitry of the RFID tag to the timed non-synchronized low power sleep mode for the predefined non-synchronized sleep time if the number of immediately previous consecutive sleep times is less than a predefined threshold, or operating the RFID tag in a timed powered up non-synchronized listening mode for a predefined non-synchronized tag listening time during which the first band receiver or transceiver circuitry actively listens for transmitted first band RF signal interrogator polling signals if the number of immediately previous consecutive sleep times is greater than or equal to a predefined threshold.

20. The system of claim 19, wherein the duration of the predefined non-synchronized tag listening time is greater than or equal to a predefined value of the frequency of the interrogator polling signals.

21. The system of claim 19, wherein the at least one processing device is further configured to again operate the RFID tag in the synchronized state upon receipt of a periodic interrogator polling signal during the non-synchronized tag listening time of the non-synchronized listening mode.

22. The system of claim 12, wherein the first band is a narrow band frequency modulation (NBFM) frequency band;

and wherein the second band is an ultra-wideband (UWB) frequency band.

23. A method of operating a radio frequency identification (RFID) tag within a radio frequency identification (RFID) communication environment, comprising:

alternately operating at least one RFID tag between a non-synchronized state with a periodic interrogator polling signal and a synchronized state with a periodic interrogator polling signal, the RFID tag being configured to receive periodic first band RF signal interrogator polling signals and to transmit second band RF signal response signals in response thereto, the first band being a multiple channel-based frequency band and the second band being a non-channel based frequency band;

wherein in the non-synchronized state of the method comprises;

operating the RFID tag in a timed non-synchronized low power sleep mode for a predefined non-synchronized sleep time during which the RFID tag does not listen for transmitted first band RF signal interrogator polling signals,

then waking up the RFID tag to perform one or more tag processing operations,

then returning the RFID tag to the timed non-synchronized low power sleep mode for the predefined non-synchronized sleep time if the number of immediately previous consecutive sleep times is less than a predefined threshold, or operating the RFID tag in a timed powered up non-synchronized listening mode for a predefined non-synchronized tag listening time during which the RFID tag actively listens for transmitted first band RF signal interrogator polling signals if the number of immediately previous consecutive sleep times is greater than or equal to a predefined threshold; and

wherein in the synchronized state of the method comprises;

operating the RFID tag in a timed synchronized low power sleep mode for a predefined synchronized sleep time during which the RFID tag does not listen for transmitted first band RF signal interrogator polling signals,

then waking up the RFID tag to operate in a timed powered up synchronized listening mode for a predefined synchronized tag listening time during which the RFID tag actively listens for transmitted first band RF signal interrogator polling signals,

performing the following steps if an interrogator polling signal is received during a given synchronized listening mode;

processing the latest received interrogator polling signal, performing one or more tag processing operations, increasing or decreasing the length of the predefined synchronized sleep time based on the given receipt time of the interrogator polling signal as necessary to maintain a predefined alignment time between the start time of the synchronized listening mode and the given receipt time of the periodic interrogator polling signal, and then returning the RFID tag to the timed synchronized low power sleep mode for the predefined synchronized sleep time, and

performing the following steps if an interrogator polling signal is not received during a given synchronized listening mode;

decreasing the length of the predefined synchronized sleep time by an incremental amount of time, performing one or more tag processing operations, and then returning the RFID tag to the timed synchronized low power sleep mode for the predefined synchronized sleep time if the number of consecutive times that an interrogator polling signal has not been received is less than a predefined threshold, or then operating the RFID tag in the non-synchronized state if the number of consecutive times that an interrogator polling signal has not been received is greater than a predefined threshold.

24. The method of claim 23, wherein the first band is a narrow band frequency modulation (NBFM) frequency band;

and wherein the second band is an ultra-wideband (UWB) frequency band.

25. A frequency identification (RFID) tag system, comprising:

first band receiver or transceiver circuitry configured to receive periodic first band RF signal interrogator polling signals and second band transmitter circuitry configured to transmit second band RF signal response signals in response thereto, the first band being a multiple channel-based frequency band and the second band being a non-channel based frequency band; and

at least one processing device to repeatedly and alternately operate the RFID tag between a non-synchronized state with a periodic interrogator polling signal and a synchronized state with a periodic interrogator polling signal;

wherein in the non-synchronized state the at least one processing device is configured to;

operate the first band receiver or transceiver circuitry of the RFID tag in a timed non-synchronized low power sleep mode for a predefined non-synchronized sleep time during which the first band receiver or transceiver circuitry does not listen for transmitted first band RF signal interrogator polling signals,

then wake up the first band receiver or transceiver circuitry to perform one or more tag processing operations,

then return the first band receiver or transceiver circuitry to the timed non-synchronized low power sleep mode for the predefined non-synchronized sleep time if the number of immediately previous consecutive sleep times is less than a predefined threshold, or operate the first band receiver or transceiver circuitry in a timed powered up non-synchronized listening mode for a predefined non-synchronized tag listening time during which the first band receiver or transceiver circuitry actively listens for transmitted first band RF signal interrogator polling signals if the number of immediately previous consecutive sleep times is greater than or equal to a predefined threshold; and

wherein in the synchronized state the at least one processing device is configured to;

operate the first band receiver or transceiver circuitry in a timed synchronized low power sleep mode for a predefined synchronized sleep time during which the first band receiver or transceiver circuitry does not listen for transmitted first band RF signal interrogator polling signals,

then wake the first band receiver or transceiver circuitry to operate in a timed powered up synchronized listening mode for a predefined synchronized tag listening time during which the first band receiver or transceiver circuitry actively listens for transmitted first band RF signal interrogator polling signals,

perform the following steps if an interrogator polling signal is received during a given synchronized listening mode;

process the latest received interrogator polling signal, perform one or more tag processing operations and increase or decrease the length of the predefined synchronized sleep time based on the given receipt time of the interrogator polling signal as necessary to maintain a predefined alignment time between the start time of the synchronized listening mode and the given receipt time of the periodic interrogator polling signal, and then return the RFID tag to the timed synchronized low power sleep mode for the predefined synchronized sleep time, and

perform the following steps if an interrogator polling signal is not received during a given synchronized listening mode;

decrease the length of the predefined synchronized sleep time by an incremental amount of time and perform one or more tag processing operations, and then return circuitry of the RFID tag to the timed synchronized low power sleep mode for the predefined synchronized sleep time if the number of consecutive times that an interrogator polling signal has not been received is less than a predefined threshold, or then operate the RFID tag in the non-synchronized state if the number of consecutive times that an interrogator polling signal has not been received is greater than a predefined threshold.

26. The system of claim 25, wherein the first band is a narrow band frequency modulation (NBFM) frequency band;

and wherein the second band is an ultra-wideband (UWB) frequency band.