RFID device, system and method of operation including a hybrid backscatter-based RFID tag protocol compatible with RFID, bluetooth and/or IEEE 802.11x infrastructure

• US 20030104848A1
• Filed: 11/08/2002
• Published: 06/05/2003
• Est. Priority Date: 11/30/2001
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Brideglall, Raj
• Granted Patent: US 7,215,976 B2
• Time in Patent Office: Days
• US Class Current: 455/574
• 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 19/07733 the record carrier containing at least one further contact interface not conform ISO-7816
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10297 arrangements for handling protocols designed for non-contact record carriers such as RFIDs NFCs, e.g. ISO/IEC 14443 and 18092 cryptographic protocols H04L9/00; network security protocols H04L63/00; real-time communication protocols in data switching networks H04L65/00; network protocols for data switching network services H04L67/00

Abstract

An RFID system includes a hybrid backscatter-based RFID tag protocol-compatible with existing 802.11x/Bluetooth Standards as well as RFID standards. The tag is linked to a multi-protocol Interrogator via a generated RF Continuous Wave (CW) field. The tag includes an antenna coupled to an RFID and a Bluetooth/802.11x transceiver section. A Protocol Processor services RFID and transceiver sections and is coupled to the antenna via a backscatter switch. The Interrogator can switch the tag to an RFID backscatter radiation mode where the processor switches the antenna impedance to reflect the CW signal. For transceiver operation the processor switches antenna impedance in synchronization with a frame organized bit stream. For reception, the RFID section utilizes demodulation techniques, typically Amplitude Shift Keying (ASK), and provides a wake up mode within a predetermined distance of the Interrogator. The transceiver may operate in a backscatter or regular mode as directed by an Access Point.

Claims

1. An RFID communications device comprising:

a) a substrate;

b) a first antenna disposed on the substrate and coupled to a low power communication transceiver responsive to low power communication protocols;

c) an RFID transceiver coupled to a second antenna and implementing ASK demodulation of signals received at the antenna;

d) a processor coupled to the low power transceiver and the RFID transceiver; and

e) switching apparatus which switches the device between a backscatter mode of operation and a low power communication mode of operation in response to an input signal.

2. The RFID device of claim 1 further comprising:

f) wake-up apparatus in the RFID transceiver, the apparatus powering down the device when not in use and turning on the device when within a predetermined distance of an RF signal source.

3. The RFID device of claim 2 further comprising;

g) signal strength threshold apparatus included for turning on the wake up apparatus when within the pre-determined distance of the RF signal source.

4. The RFID device of claim 3 further comprising:

h) a programmable digital resistor included in the signal strength threshold apparatus for implementing a threshold to turn on the processor.

5. The RFID device of claim 1 further comprising:

i) mode-determining apparatus which examines the input signal characteristics to determine whether backscatter or low power communication protocol is required.

6. The RFID device of claim 1 further comprising:

j) powering off apparatus which turns off the low power communication transceiver when proceeding with backscatter based RFID communication.

7. The RFID device of claim 1 further comprising:

k) signal examining apparatus which examines the validity of received frames from the RFID transceiver and an ASK demodulator to determine the required RFID communication protocol.

8. The RFID device of claim 1 further comprising:

l) modulating apparatus which modulates the second antenna impedance to reflect Continuous Wave (CW) energy from a base station or interrogator.

9. The RFID device of claim 1 further comprising:

m) a power supply coupled to the processor for operation of the device in an active mode.

10. The RFID device of claim 1 further comprising:

n) connecting apparatus which connects the switching apparatus to the second antenna and to the processor.

11. The RFID device of claim 1 wherein the low power communication is Bluetooth and/or IEEE 802.11x.

12. An RFID communication system comprising:

a) a multi-protocol interrogator generating an RF continuous wave (CW) field;

b) an RFID tag linked to the interrogator by the CW field; and

c) means included in the RFID tag responsive to the interrogator for switching between backscatter modulation using amplitude shift keying and Bluetooth and/or 802.11x transceiver operation.

13. The communication system of claim 12 further comprising:

d) interrogator apparatus which enables the interrogator to negotiate for collision-free time slots from other transmitters in the system area.

14. The communication system of claim 12 further comprising:

e) RF field generating apparatus which generates a CW field reflected by the RFID tag device

15. The communication system of claim 12 further comprising

f) command generating apparatus which generates a command commanding the RFID tag to select a preferred communication protocol for communicating with the interrogator.

16. An RFID communication system having wide area network capability, comprising:

a) an RFID transceiver coupled to a first antenna and a processor in an RFID tag;

b) a low power communication system in the RFID tag separated from the RFID receiver, the system coupled to a low power communication antenna and to the processor;

c) a memory coupled to the processor for storing network element of the RFID receiver and low power communication sections; and

d) means to activate the RFID transceiver, retrieve an IP address of the RFID tag and transfer data to the RFID tag from a wide area network or vice versa.

17. An RFID communication system having low power characteristics, comprising

a) an RFID transceiver coupled to an antenna and a processor in an RFID tag, the RFID transceiver adapted for sleep mode operation;

b) a low power communication system in the RFID tag separated from the RFID transceiver, the low power communication system coupled to a low power communication antenna and to the processor;

c) a memory coupled to the processor for storing timer information of the low power communication system; and

d) means for powering down the low power communication section and utilizing the sleep mode condition of the RFID receiver, when awakened, to trigger the low power communication system for operation.

18. A method of communication in an RFID communication system, comprising:

a) generating an RF continuous wave (CW) field by a multi-protocol interrogator;

b) coupling a hybrid backscatter based RFID tag to the interrogator by the CW field, the tag including RFID signaling and low power communication;

c) switching the RFID tag between the RFID signaling and the low power communication; and

d) selecting backscatter radiation for the RFID signaling or the low power communication.

19. The method of communication of claim 18 further comprising:

e) powering down the low power communication and utilizing a sleep mode for the RFID, when awakened, to trigger the operation of the low power communication.

20. The method of communication of claim 18 further comprising:

f) storing network elements related to the RFID signaling and low power communication;

d) activating the RFID signaling and retrieving an IP address of the RFID tag; and

e) transferring data to the RFID tag from a wide area network or vice versa.

21. An RFID communication system, comprising:

a) an RFID tag including an RFID transceiver and a low power communication transceiver;

b) a processor coupled to the transceivers;

c) a multi-protocol interrogator linked to the RFID tag;

d) switching means responsive to the RFID transceiver to enable operation of the RFID transceiver in passive and semi-passive modes.

22. The RFID communication system of claim 21 further comprising:

e) mode-determining apparatus in an RFID tag which examines an input signal characteristics from the interrogator to determine whether backscatter or low power communication protocol is required.

23. The RFID communication system of claim 21 further comprising:

f) wake up apparatus that accumulates energy on a capacitor which provides a threshold based wake up signal to the processor where the wake up signal is derived from a division of the capacitor voltage by a digital resistor.

24. The RFID communication system of claim 23 further comprising:

g) signal strength threshold apparatus in the tag for turning on the wake up apparatus when the tag is within a pre-determined distance of a signal source.

25. The RFID communication system of claim 21 further comprising

h) signal examining apparatus in the tag examining the validity of received frames from an ASK demodulator to determine the required RFID communication protocol.

26. The RFID communication system of claim 21 further comprising

i) auxiliary sleep mode apparatus including a built-in timer that keeps a real-time clock enabling the low power transceiver to be completely powered down while tracking network timers and just before awakening powering up the low power transceiver permitting upload of time-advanced network timers.

27. The RFID communication system of claim 21 further comprising

j) a non-volatile memory which serves as a common repository for system data that can be communicated between RFID, WLAN, and WWAN networks.

28. The RFID communication system of claim 21 further comprising:

k) a regulated charger block connected to the processor and utilizing energy stored in the tag to trickle charge a battery each time the tag or a nearby tag is interrogated.

29. The RFID communication system of claim 23 wherein the wake up apparatus is disabled by turning off a “

listener”

transistor when RFID operation is not required or a low power transceiver is operating.

30. A method of operating an RFID communication system, comprising:

a) receiving an RF signal from a multi-protocol interrogator in an RFID tag;

b) examining the signal to determine RFID or low power communication for the RFID tag;

c) initiating operation of the RFID tag in a backscatter radiation mode if RFID operation is identified in the signal;

d) initiating operation of the RFID tag in a low power communication mode if identified in the signal;

e) activating an inquiry mode for a transceiver when the tag is in the low power communication mode;

f) conducting a paging operation for the transceiver to connect with an access point; and

transferring data from the RFID tag to the access point for delivery to the interrogator.

31. The method of claim 30 further comprising:

g) storing data and WWAN network information in the RFID tag; and

exchanging data with the WWAN network via the access point and the interrogator when the RFID tag is in the low power communication mode.

32. In an RFID tag including an RF transceiver and a low power communication transceiver coupled to a processor, a method of low power operation, comprising:

a) operating the tag in a sleep state with the RF transceiver, low power communication transceiver and the processor in a powered down state;

b) receiving an RF signal and storing RF energy in a storage device;

c) providing a threshold based wake-up signal to the processor when sufficient energy is stored in the storage device;

d) triggering the processor to wake up in response to the threshold based wakeup signal;

e) examining the RF signal to determine tag operation whether in an RF transceiver or a low power communication transceiver mode of operation;

f) enabling the RF transceiver and the low power communication transceiver to respond to a determined mode of operation; and

g) powering down the RF transceiver, the low power communication transceiver and the processor after completion of the determined mode of operation.

33. The method of claim 32 further comprising:

h) tracking network timers in a local timing device;

i) powering up the low power communication transceiver according to required network wake-up intervals tracked by the local timing device.

34. The method of claim 32 further comprising:

j) determining whether RF transceiver mode of operation is with or without backscatter radiation.

35. The method of claim 32 further comprising:

k) determining whether low power communication transceiver operation is with or without backscatter radiation.