Reflective communication using radio-frequency devices

• US 7,697,946 B2
• Filed: 04/25/2003
• Issued: 04/13/2010
• 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:
  US10/423,824
• Publication Number:
  US 20040043747A1
• Time in Patent Office: 2,545 Days
• Field of Search: 455/41.2, 455/500, 455/526, 455/334, 455/337, 455/130, 340/10
• US Class Current: 455/500
• 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

The present invention relates to a reflective communication system that allows information from wireless communication devices, such as radio-frequency identification devices (RFID), to be reflectively communicated to a receiver in lieu of using a separate communication system. A transmitter transmits a communication signal, having a carrier frequency, to the wireless communication device to provide power. The wireless communication device modulates a data signal onto the communication signal to form a reflected data signal. The wireless communication device reflects the reflected data signal directly to the receiver. In this manner, the process of communicating information from a wireless communication device is accomplished in one communication system rather than two. If the receiver also directly receives the communication signal from the transmitter, the receiver can determine the location of the wireless communication device relative to the transmitters.

Claims

1. A reflective communication system, comprising:

a wireless communication device configured to receive, from a first transmitter of a plurality of transmitters, an incident radio signal mixed with a spread spectrum code associated with the first transmitter and to reflectively modulate the incident radio signal with a data signal having a modulation to form a reflected data signal; and

a receiver configured to;

store, in a receiver memory, a spread spectrum coding sequence containing a plurality of receiver spread spectrum codes that respectively correlate to spread spectrum codes that are each associated with a transmitter from the plurality of transmitters;

store, in the receiver memory, information indicating a physical location of each transmitter;

receive the incident radio signal from the first transmitter and the reflected data signal from the wireless communication device;

correlate a receiver spread spectrum code from the spread spectrum coding sequence to the spread spectrum code associated with the first transmitter by mixing the receiver spread spectrum code with the reflected data signal to recover the reflected data signal in a de-spread format, wherein the spread spectrum coding sequence is generated from a shift register of a defined number of bits which are combined in a logic function and fed back into the shift register input;

recover the reflected data signal by;

detecting whether the reflected data signal was successfully de-spread during the mixing process using the receiver spread spectrum code;

if the reflected data signal was not successfully de-spread, shifting the receiver spread spectrum code in the spread spectrum coding sequence by one bit or a fraction of one bit and mixing the reflected data signal with the shifted receiver spread spectrum code; and

repeating the detecting, shifting, and mixing until the receiver spread spectrum code correlates to the spread spectrum code associated with the first transmitter and the reflected data signal is successfully de-spread;

identify the first transmitter based on the correlation of the receiver spread spectrum code that successfully de-spread the reflected data signal to the spread spectrum code associated with the first transmitter;

for a second transmitter from the plurality of transmitters, repeat the steps of receiving an incident radio signal, receiving a reflected data signal from the wireless communication device, correlating a receiver spread spectrum code to the spread spectrum code associated with the second transmitter, recovering the reflected data signal, and identifying the second transmitter; and

determine a location of the wireless communication device by;

determining a time delay between the reflected data signal and the incident radio signal for each of the first and second transmitters from the plurality of transmitters; and

using triangulation, identifying the location of the wireless communication device based on the determined time delays and the stored information indicating the physical location of each of the identified first and second transmitters.

2. The system of claim 1, wherein the incident radio signal is a 2.45 GHz GFSK modulated signal.

3. The system of claim 1, wherein the receiver is further configured to remove the modulation from said data signal to form data.

4. The system of claim 1, wherein the receiver further comprises a mixer configured to mix the incident radio signal with the reflected data signal to remove a first modulation from the reflected data signal to form the data signal.

5. The system of claim 4, wherein the receiver further comprises a demodulator configured to demodulate the modulation from the data signal to form data.

6. The system of claim 1, further comprising a transmitter configured to mix the spread spectrum code with the incident radio signal and transmit the incident radio signal in a spread format.

7. The system of claim 6, wherein the receiver is configured to choose a receiver spread spectrum code that correlates to the spread spectrum code used by a chosen one of a plurality of transmitters to receive reflected data signals from the wireless communication device in the field of view of the chosen one of the transmitters, and wherein each transmitter of the plurality of transmitters is respectively configured to mix the incident radio signal with a different spread spectrum code.

8. The system of claim 7, further comprising distinguishing the chosen one of the plurality of transmitters based on an association of the chosen transmitter with the spread spectrum code and the correlation of the receiver spread spectrum code that successfully de-spread the reflected data signal with the spread spectrum code.

9. The system of claim 6, wherein the transmitter comprises a Bluetooth compatible transceiver.

10. The system of claim 1, wherein the data signal includes information stored in the wireless communication device.

11. The system of claim 10, wherein the information stored in the wireless communication device is related to a container associated with the wireless communication device.

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

13. The system of claim 1, wherein the spread spectrum codes in the spread spectrum coding sequence have a low cross-correlation index.

14. The system of claim 1, wherein the receiver is further configured to determine the location of the wireless communication device based on a known location of the transmitter and the determined distance between the wireless communication device and the transmitter.

15. A method of processing a data signal from a wireless communication device that uses an incident radio signal as a communication medium, the method comprising:

storing, in a memory, a spread spectrum coding sequence containing a plurality of receiver spread spectrum codes that respectively correlate to spread spectrum codes that are each associated with a transmitter from a plurality of transmitters;

storing, in the memory, information indicating a physical location of each transmitter;

for a first transmitter from the plurality of transmitters;

receiving an incident radio signal from the first transmitter, wherein the incident radio signal has been mixed with a spread spectrum code that is associated with the first transmitter;

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

recovering the reflected data signal by;

mixing one or more receiver spread spectrum codes in the spread spectrum coding sequence with the reflected data signal;

detecting whether the reflected data signal was successfully de-spread during the mixing process;

if the reflected data signal was not successfully de-spread, shifting the receiver spread spectrum coding sequence by one bit or a fraction of one bit and mixing the reflected data signal with the shifted receiver spread spectrum code; and

repeating the detecting, shifting, and mixing until the receiver spread spectrum code correlates to the spread spectrum code associated with the first transmitter and the reflected data signal is successfully de-spread;

identifying the first transmitter based on the correlation of the receiver spread spectrum code that successfully de-spread the reflected data signal to the spread spectrum code associated with the first transmitter;

for a second transmitter from the plurality of transmitters, repeating the steps of receiving an incident radio signal, receiving a reflected data signal from the wireless communication device, recovering the reflected data signal, and identifying the second transmitter; and

determining a location of the wireless communication device by;

determining a time delay between the reflected data signal and the incident radio signal for each of the first and second transmitters from the plurality of transmitters; and

using triangulation, identifying the location of the wireless communication device based on the determined time delays and the stored information indicating the physical location of each of the identified first and second transmitters.

16. The method of claim 15, further comprising removing the modulation from the reflected data signal to form data.

17. The method of claim 16, wherein said removing the modulation comprises mixing the incident radio signal with the reflected data signal.

18. The method of claim 16, wherein said removing the modulation comprises demodulating the modulation from the reflected data signal.

19. The method of claim 15, further comprising determining a distance between the wireless communication device and the transmitter that transmitted the incident radio signal based on a time delay between the received incident radio signal and the received reflected data signal.

20. The method of claim 19, further comprising determining an approximate location of the wireless communication device based on the determined distance between the wireless communication device and the transmitter and a known location of the transmitter.

21. A receiving device comprising:

a receiver configured to receive both an incident radio signal from a first transmitter of a plurality of transmitters and a reflected data signal from a wireless communication device, wherein the incident radio signal has been spread with a spread spectrum code that is associated with the first transmitter, and wherein the reflected data signal has been formed from reflective modulation of the incident radio signal with a data signal having a modulation; and

a mixer configured to mix one or more receiver spread spectrum codes in a spread spectrum coding sequence with the reflected data signal to identify a receiver spread spectrum code that correlates to the spread spectrum code associated with the first transmitter and successfully de-spreads the reflected data signal,

wherein the receiving device is configured to;

store, in a receiving device memory, the spread spectrum coding sequence which contains a plurality of receiver spread spectrum codes that respectively correlate to spread spectrum codes that are each associated with a transmitter from the plurality of transmitters;

store, in the receiving device memory, information indicating a physical location of each transmitter; and

recover the reflected data signal by;

detecting whether the reflected data signal was successfully de-spread during the mixing process using the receiver spread spectrum code;

if the reflected data signal was not successfully de-spread, shifting the receiver spread spectrum code in the spread spectrum coding sequence by one bit or a fraction of one bit and mixing the reflected data signal with the shifted receiver spread spectrum code;

repeating the detecting, shifting, and mixing until the receiver spread spectrum code correlates to the spread spectrum code associated with the first transmitter and the reflected data signal is successfully de-spread;

identify the first transmitter based on the correlation of the receiver spread spectrum code that successfully de-spread the reflected data signal to the spread spectrum code associated with the first transmitter;

for a second transmitter from the plurality of transmitters, repeat the steps of receiving an incident radio signal, receiving a reflected data signal from the wireless communication device, mixing the one or more receiver spread spectrum codes in the spread spectrum coding sequence with the reflected data signal, recovering the reflected data signal, and identifying the second transmitter; and

determine a location of the wireless communication device by;

determining a time delay between the reflected data signal and the incident radio signal for each of the first and second transmitters from the plurality of transmitters; and

using triangulation, identifying the location of the wireless communication device based on the determined time delays and the stored information indicating the physical location of each of the identified first and second transmitters.

22. The receiving device of claim 21, further comprising a demodulator configured to demodulate the modulation from the data signal to form data.

23. The receiving device of claim 21, wherein the receiver is further configured to remove the modulation from the data signal to form data.

24. The receiving device of claim 21, wherein the receiver is further configured to determine a distance between the wireless communication device and the transmitter that transmitted the incident radio signal based on a time delay between the received incident radio signal and the received reflected data signal.

25. The receiving device of claim 24, wherein the receiver is further configured to determine an approximate location of the wireless communication device based on a known location of the transmitter and the determined distance between the wireless communication device and the transmitter.

26. A reflective communication system, comprising:

communication means for receiving, from a first transmitter of a plurality of transmitters, an incident radio signal mixed with a spread spectrum code associated with the first transmitter and reflectively modulating the incident radio signal with a data signal having a modulation to form a reflected data signal; and

receiver means for receiving the incident radio signal and the reflected data signal and determining a location of the communication means,

wherein the receiver means is further configured to correlate a receiver spread spectrum code from a spread spectrum coding sequence to the spread spectrum code associated with the first transmitter by mixing the receiver spread spectrum code with the reflected data signal to recover the reflected data signal in a de-spread format, wherein the spread spectrum coding sequence is generated from a shift register of a defined number of bits which are combined in a logic function and fed back into the shift register input, and

wherein the receiver means is further configured to;

store, in a receiver means memory, the spread spectrum coding sequence which contains a plurality of receiver spread spectrum codes that respectively correlate to spread spectrum codes that are each associated with a transmitter from the plurality of transmitters;

store, in the receiver means memory, information indicating a physical location of each transmitter; and

recover the reflected data signal by;

detecting whether the reflected data signal was successfully de-spread during the mixing process using the receiver spread spectrum code;

if the reflected data signal was not de-spread, shifting the receiver spread spectrum code in the spread spectrum coding sequence by one bit or a fraction of one bit and mixing the reflected data signal with the shifted receiver spread spectrum code; and

repeating the detecting, shifting, and mixing until the receiver spread spectrum code correlates to the spread spectrum code associated with the first transmitter and the reflected data signal is successfully de-spread;

identify the first transmitter based on the correlation of the receiver spread spectrum code that successfully de-spread the reflected data signal to the spread spectrum code associated with the first transmitter;

for a second transmitter from the plurality of transmitters, repeat the steps of receiving an incident radio signal, receiving a reflected data signal from the communication means, mixing the receiver spread spectrum code with the reflected data signal, recovering the reflected data signal, and identifying the second transmitter; and

determine the location of the communication means by;

determining a time delay between the reflected data signal and the incident radio signal for each of the first and second transmitters from the plurality of transmitters; and

using triangulation, identifying the location of the communication means based on the determined time delays and the stored information indicating the physical location of each of the identified first and second transmitters.

27. The system of claim 26, wherein the receiver means is further configured to determine the location of the wireless communication device based on a known location of the transmitter and the determined distance between the wireless communication device and the transmitter.

28. A receiving device comprising:

receiver means for receiving both an incident radio signal from a first transmitter of a plurality of transmitters and a reflected data signal from a wireless communication device, wherein the incident radio signal has been spread with a spread spectrum code that is associated with the first transmitter, and wherein the reflected data signal has been formed from reflective modulation of the incident radio signal with a data signal having a modulation; and

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

wherein the receiving device is configured to;

store, in a receiving device memory, the spread spectrum coding sequence which contains a plurality of receiver spread spectrum codes that respectively correlate to spread spectrum codes that are each associated with a transmitter from the plurality of transmitters;

store, in the receiving device memory, information indicating a physical location of each transmitter; and

recover the reflected data signal by;

detecting whether the reflected data signal was successfully de-spread during the mixing process using the receiver spread spectrum code;

if the reflected data signal was not successfully de-spread, shifting the receiver spread spectrum code in the spread spectrum coding sequence by one bit or a fraction of one bit and mixing the reflected data signal with the shifted receiver spread spectrum code; and

repeating the detecting, shifting, and mixing until the receiver spread spectrum code correlates to the spread spectrum code associated with the first transmitter and the reflected data signal is successfully de-spread; and

wherein the receiving device is further configured to;

identify the first transmitter based on the correlation of the receiver spread spectrum code that successfully de-spread the reflected data signal to the spread spectrum code associated with the first transmitter;

for a second transmitter of the plurality of transmitters, repeat the steps of receiving an incident radio signal, receiving a reflected data signal from the wireless communication device, mixing the one or more receiver spread spectrum codes in the spread spectrum coding sequence with the reflected data signal, recovering the reflected data signal, and identifying the second transmitter; and

determine a location of the wireless communication device by;

determining a time delay between the reflected data signal and the incident radio signal for each of the first and second transmitters from the plurality of transmitters; and

using triangulation, identifying the location of the wireless communication device based on the determined time delays and the stored information indicating the physical location of each of the identified first and second transmitters.

29. The receiving device of claim 28, wherein the receiver means is further configured to determine a distance between the wireless communication device and the transmitter that transmitted the incident radio signal based on a time delay between the received incident radio signal and the received reflected data signal.

30. The receiving device of claim 29, wherein the receiver means is further configured to determine an approximate location of the wireless communication device based on a known location of the transmitter and the determined distance between the wireless communication device and the transmitter.

31. A reflective communication system, comprising:

a plurality of transmitters, wherein each transmitter has a different spread spectrum code associated therewith that is mixed with an incident radio signal;

a wireless communication device configured to receive, from a first transmitter of the plurality of transmitters, an incident radio signal mixed with a spread spectrum code associated with the first transmitter and reflectively emit a reflected data signal based on the incident radio signal; and

a receiver configured to;

store, in a receiver memory, a spread spectrum coding sequence containing a plurality of receiver spread spectrum codes that each respectively correlate to the different spread spectrum code associated with each transmitter from the plurality of transmitters;

store, in the receiver memory, information indicating a physical location of each transmitter;

receive the incident radio signal and the reflected data signal; and

recover the reflected data signal received from the wireless communication device by;

mixing the reflected data signal with a receiver spread spectrum code;

detecting whether the reflected data signal was successfully de-spread during the mixing process using the receiver spread spectrum code;

if the reflected data signal was not successfully de-spread, shifting the receiver spread spectrum code in the spread spectrum coding sequence by one bit or a fraction of one bit and mixing the reflected data signal with the shifted receiver spread spectrum code; and

repeating the detecting, shifting, and mixing until the receiver spread spectrum code correlates to the spread spectrum code associated with the first transmitter and the reflected data signal is successfully de-spread;

identify the first transmitter based on the correlation of the receiver spread spectrum code that successfully de-spread the reflected data signal to the spread spectrum code associated with the first transmitter;

for a second transmitter from the plurality of transmitters, repeat the steps of receiving an incident radio signal, receiving a reflected data signal from the wireless communication device, recovering the reflected data signal, and identifying the second transmitter; and

determine a location of the wireless communication device by;

determining a time delay between the reflected data signal and the incident radio signal for each of the first and second transmitters from the plurality of transmitters; and

using triangulation, identifying the location of the wireless communication device based on the determined time delays and the stored information indicating the physical location of each of the identified first and second transmitters.

32. The system of claim 31, wherein the receiver is further configured to identify the transmitter from other transmitters in the plurality of transmitters based on the association of the transmitter with the identified receiver spread spectrum code.

33. The system of claim 32, wherein the different spread spectrum codes used by the plurality of transmitters have a low cross-correlation index.

34. The system of claim 31, wherein the receiver is further configured to determine a distance between the wireless communication device and the transmitter that transmitted the incident radio signal based on a time delay between the received incident radio signal and the received reflected data signal.

35. The system of claim 34, wherein the receiver is further configured to determine an approximate location of the wireless communication device based on a known location of the transmitter and the determined distance between the wireless communication device and the transmitter.