Reflective communication using radio-frequency devices

• US 7,970,353 B2
• Filed: 02/25/2010
• Issued: 06/28/2011
• Est. Priority Date: 06/04/2002
• Status: Expired due to Fees

• Current Assignee: Mineral Lassen LLC (Intellectual Ventures LLC)
• Original Assignee: Mineral Lassen LLC (Intellectual Ventures LLC)
• Inventors: Forster, Ian J.
• Primary Examiner(s): Pan; Yuwen
• Application Number:
  US12/712,765
• Publication Number:
  US 20100151892A1
• Time in Patent Office: 488 Days
• Field of Search: 455/41.2, 340/572.2, 340/572.7
• US Class Current: 455/41.2
• CPC Class Codes: G01S 13/003 Bistatic radar systems; Multistatic radar systems
• CPC Class Codes: G01S 13/325 using transmission of coded signals, e.g. P.S.K. signals
• CPC Class Codes: G01S 13/756 using a signal generator for modifying the reflectivity of the reflector G01S13/758 takes precedence
• CPC Class Codes: G01S 13/758 using a signal generator powered by the interrogation signal
• CPC Class Codes: G01S 13/878 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S13/874 takes precedence
• CPC Class Codes: G06K 17/0022 arrangements or provisious for transferring data to distant stations, e.g. from a sensing device "transfer between computer elements G06F13/00 "; data-transmission H04L
• 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 7/10079 the collision being resolved in the spatial domain, e.g. temporary shields for blindfolding the interrogator in specific directions
• CPC Class Codes: G06K 7/10316 using at least one antenna particularly designed for interrogating the wireless record carriers antennas in general H01Q1/22
• CPC Class Codes: G06K 7/10346 the antenna being of the far field type, e.g. HF types or dipoles

Abstract

A reflective communication system allows information from wireless communication devices, such as radio-frequency identification devices (RFID), to be reflectively communicated to a receiver. A transmitter at a known location transmits a communication signal to the wireless communication device. The wireless communication device modulates a data signal onto the communication signal to form a reflected data signal and reflects the reflected data signal to the receiver. The receiver receives the communication signal from the transmitter and can determine a distance between the wireless communication device and the transmitter based on data that includes a time delay between receipt of the communication signal and receipt of the reflected data signal by the receiver. The receiver can further determine the approximate location of the wireless communication device based on data that includes the known location of the transmitter and the determined distance between the wireless communication device and the transmitter.

Claims

1. A method of processing a reflected data signal, the method comprising:

receiving, at a receiver, an incident radio signal and the reflected data signal, wherein the incident radio signal is received from a transmitter located at a known location and the reflected data signal is received from a wireless communication device that uses the incident radio signal as a communication medium, wherein the incident radio signal has been mixed with a transmitter spread spectrum code that is associated with the transmitter, and wherein the wireless communication device has reflectively modulated the incident radio signal with a data signal having a modulation to form the reflected data signal;

analyzing the reflected data signal received from the wireless communication device to identify the transmitter spread spectrum code of the incident radio signal that was reflectively modulated by the wireless communication device;

identifying the transmitter that transmitted the incident radio signal based on the identified transmitter spread spectrum code;

determining a distance between the wireless communication device and the transmitter that transmitted the incident radio signal based on data that includes a time delay between receipt of the incident radio signal and receipt of the reflected data signal by the receiver; and

determining an approximate location of the wireless communication device based on data that includes the known location of the transmitter and the determined distance between the wireless communication device and the transmitter.

2. The method of claim 1, further comprising removing the modulation from the reflected data signal to form data.

3. The method of claim 2, further comprising, at the receiver, mixing the incident radio signal with the reflected data signal.

4. The method of claim 2, wherein said removing the modulation comprises demodulating the modulation from the reflected data signal.

5. The method of claim 1, wherein said analyzing the reflected data signal comprises correlating a receiver spread spectrum code from a spread spectrum coding sequence in the receiver to the transmitter spread spectrum code in the reflected data signal by mixing the receiver spread spectrum code with the reflected data signal and determining whether said mixing results in de-spreading the reflected data signal so that the reflected data signal is recovered in unspread format.

6. The method of claim 5, further comprising sequencing through the receiver spread spectrum codes in the spread spectrum coding sequence to identify the receiver spread spectrum code that, when mixed with the reflected data signal, results in de-spreading the reflected data signal and thereby correlates to the transmitter spread spectrum code.

7. The method of claim 1, wherein the reflected data signal is received from a wireless communication device in a field of transmission of a transmitter in a plurality of transmitters, the method further comprising choosing a receiver spread spectrum code that correlates to the transmitter spread spectrum code and identifies the transmitter that transmitted the incident radio signal.

8. The method of claim 7, further comprising mixing the receiver spread spectrum code with the reflected data signal to de-spread the reflected data signal and recover the reflected data signal in unspread format.

9. The method of claim 1, wherein the reflected data signal communicates information stored in the wireless communication device that is related to a container associated with the wireless communication device.

10. The method of claim 1, wherein the incident radio signal is reflectively modulated with a Manchester bi-phase encoded data signal.

11. A reflective communication system, comprising:

transmitting means for transmitting an incident radio signal mixed with a transmitter spread spectrum code to a wireless communication device, wherein the transmitter spread spectrum code is associated with the transmitting means;

receiving means for receiving both a reflected data signal from the wireless communication device and the incident radio signal from the transmitting means, wherein the wireless communication device has reflectively modulated the incident radio signal with a data signal having a modulation to form the reflected data signal;

analyzing means for analyzing the reflected data signal to identify the transmitter spread spectrum code of the incident radio signal that was reflectively modulated by the wireless communication device;

means for identifying the transmitting means that transmitted the incident radio signal based on the identified transmitter spread spectrum code;

means for determining a distance between the wireless communication device and the transmitting means that transmitted the incident radio signal based on data that includes a time delay between receipt of the incident radio signal and receipt of the reflected data signal by the receiving means; and

means for determining an approximate location of the wireless communication device based on data that includes a known location of the transmitting means and the determined distance between the wireless communication device and the transmitting means.

12. The reflective communication system of claim 11, further comprising means for removing the modulation from the reflected data signal by mixing the incident radio signal with the reflected data signal and demodulating the modulation.

13. The reflective communication system of claim 11, wherein the analyzing means for analyzing the reflected data signal is configured to correlate a receiver spread spectrum code from a spread spectrum coding sequence to the transmitter spread spectrum code in the reflected data signal by mixing the receiver spread spectrum code with the reflected data signal and determining whether said mixing results in de-spreading the reflected data signal so that the reflected data signal is recovered in unspread format.

14. The reflective communication system of claim 13, wherein the analyzing means for analyzing the reflected data signal is further configured to sequence through the receiver spread spectrum codes in the spread spectrum coding sequence to identify the receiver spread spectrum code that, when mixed with the reflected data signal, results in de-spreading the reflected data signal and thereby correlates to the transmitter spread spectrum code.

15. The reflective communication system of claim 13, wherein the receiver spread spectrum codes in the spread spectrum coding sequence have a low cross-correlation index.

16. A reflective communication system, comprising:

means for receiving an incident radio signal from a transmitter located at a known location, wherein the incident radio signal has been mixed with a transmitter spread spectrum code that is associated with the transmitter;

means for receiving a reflected data signal from a wireless communication device, wherein the reflected data signal has been formed by reflective modulation of the incident radio signal with a data signal having a modulation;

means for mixing one or more receiver spread spectrum codes from a spread spectrum coding sequence with the reflected data signal to identify a receiver spread spectrum code that correlates to the transmitter spread spectrum code and successfully de-spreads the reflected data signal;

means for identifying the transmitter that transmitted the incident radio signal from other transmitters that use different spread spectrum codes based on the identified receiver spread spectrum code that correlates to the transmitter spread spectrum code;

means for determining a distance between the wireless communication device and the identified transmitter that transmitted the incident radio signal based on data that includes a time delay between receipt of the incident radio signal and receipt of the reflected data signal by the means for receiving the incident radio signal and the means for receiving the reflected data signal, respectively; and

means for determining an approximate location of the wireless communication device based on data that includes the known location of the identified transmitter and the determined distance between the wireless communication device and the identified transmitter.

17. The reflective communication system of claim 16, wherein the means for receiving the reflected data signal is configured to remove the modulation from the reflected data signal by mixing the incident radio signal with the reflected data signal and demodulating the modulation.

18. The reflective communication system of claim 16, wherein the means for mixing one or more receiver spread spectrum codes is configured to determine whether the mixing results in de-spreading the reflected data signal so that the reflected data signal is recovered in unspread format.

19. The reflective communication system of claim 16, wherein the means for identifying the transmitter that transmitted the incident radio signal is configured to sequence through the receiver spread spectrum codes in the spread spectrum coding sequence to identify the receiver spread spectrum code that, when mixed with the reflected data signal, results in de-spreading the reflected data signal and thereby correlates to the transmitter spread spectrum code.

20. The reflective communication system of claim 16, wherein the receiver spread spectrum codes in the spread spectrum coding sequence have a low cross-correlation index.