Reflective communication using radio-frequency devices

• US 20040043747A1
• Filed: 04/25/2003
• Published: 03/04/2004
• Est. Priority Date: 06/04/2002
• Status: Active Grant

• Current Assignee: Mineral Lassen LLC (Intellectual Ventures LLC)
• Original Assignee: Mineral Lassen LLC (Intellectual Ventures LLC)
• Inventors: Forster, Ian J.
• Granted Patent: US 7,697,946 B2
• Time in Patent Office: Days
• US Class Current: 455/334
• 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 that receives an incident radio signal having a first modulation wherein said wireless communication device reflectively modulates a data signal having a second modulation with said incident radio signal to form a reflected data signal; and

a receiver that receives said incident radio signal and said reflected data signal;

said receiver adapted to remove said first modulation from said reflected data signal to form said data signal.

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

3. The system of claim 1, wherein said receiver is adapted to remove said second modulation from said data signal to form data.

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

5. The system of claim 4, wherein said receiver further comprises a demodulator that demodulates said second modulation from said data signal to form data.

6. The system of claim 1, wherein said incident radio signal is spread using a spread spectrum code from a spread spectrum coding sequence thereby spreading said reflected data signal.

7. The system of claim 6, wherein said receiver correlates and mixes a receiver spread spectrum code from said spread spectrum coding sequence to said spread spectrum code in said reflected data signal to recover said reflected data signal in unspread format.

8. The system of claim 1, further comprising a transmitter that mixes a spread spectrum code with said incident radio signal and transmits said incident radio signal in a spread format.

9. The system of claim 8, wherein said receiver chooses a receiver spread spectrum code that correlates to the spread spectrum code used by a chosen one of said transmitters to receive said reflected data signals from said wireless communication devices in the field of view of said chosen one of said transmitter.

10. The system of claim 8, wherein said transmitter is a Bluetooth compatible transceiver.

11. A reflective communication system, comprising:

a transmitter that transmits a communication signal, comprising;

a cable having a plurality of openings in different sections of said cable; and

an antenna enclosed in said cable;

said cable having a plurality of openings in different sections so that said communication signal is transmitted at a plurality of points along said plurality of openings in said cable;

a wireless communication device that receives said communication signal from said transmitter and reflectively modulates said communication signal with a data signal having a second modulation to form a reflected data signal; and

a receiver that receives said reflected data signal.

12. The system of claim 11, wherein said receiver is adapted to remove said second modulation from said data signal to form data.

13. The system of claim 11, wherein said receiver further comprises a mixer that mixes said communication signal with said reflected data signal to remove said first modulation from said reflected data signal to form said data signal.

14. The system of claim 13, wherein said receiver further comprises a demodulator that demodulates said second modulation from said data signal to form data.

15. The system of claim 11, wherein said receiver determines the approximate location of said wireless communication device that reflected said reflected data signal by determining the delay in said reflected data signal.

16. The system of claim 11, wherein said plurality of openings each have a conductive sleeve that opens and closes to open and close said openings to control whether said communication signal radiates out of said openings.

17. A reflective communication system, comprising:

a plurality of transmitters that operate on the same frequency wherein each of said plurality of transmitters is adapted to transmit communication signals having different spread spectrum codes;

a plurality of wireless communication devices located in the transmission field of said plurality of transmitters that receive said communication signals from said plurality of transmitters wherein said plurality of wireless communication devices reflectively modulate said communication signals with data signals having a second modulation to form reflected data signals; and

a receiver adapted to receive said reflected data signals from said plurality of wireless communication devices and determine said spread spectrum codes in said reflected data signals in order to determine which of said plurality of transmitters originated said communication signals reflected by said plurality of wireless communications device to determine the approximate location of said wireless communication devices.

18. The system of claim 17, wherein said receiver is adapted to remove said second modulation from said data signal to form data.

19. The system of claim 17, wherein said receiver further comprises a mixer that mixes said communication signals with said reflected data signals to remove said first modulation from said reflected data signals to form said data signals.

20. The system of claim 19, wherein said receiver further comprises a demodulator that demodulates said second modulation from said data signals to form data.

21. The system of claim 17, wherein said receiver correlates and mixes a receiver spread spectrum code from said spread spectrum coding sequence to said spread spectrum code in said reflected data signals to recover said reflected data signals in unspread format.

22. The system of claim 17, wherein said receiver chooses a receiver spread spectrum code that correlates to the spread spectrum code used by a chosen one of said transmitters to receive said reflected data signals from one of said wireless communication devices in the field of view of said chosen one of said transmitters.

23. The system of claim 17, wherein said receiver is further adapted to receive said communication signals from a chosen one of said plurality of transmitters and compare said communication signals to the received delay of said reflected data signals to determine the distance between said wireless communication devices and said chosen one of said plurality of transmitters.

24. The system of claim 23, wherein said receiver is further adapted to determine the exact location of said wireless communication devices by triangulating at least two different communication signals to the received delay of one of said reflected data signals.

25. The system of claim 17, wherein said transmitters and said receiver are combined into a single transceiver.

26. A reflective communication system, comprising:

a plurality of transmitters that each transmit communication signals according to different frequency-hopping sequences;

a plurality of wireless communication devices located in the transmission field of said plurality of transmitters that receive said communication signals from said plurality of transmitters wherein said plurality of wireless communication devices reflectively modulate said communication signals with data signals having a second modulation to form reflected data signals; and

a receiver adapted to receive said reflected data signals from said plurality of wireless communication devices and determine said frequency hopping sequence in said reflected data signals in order to determine which of said plurality of transmitters originated said communication signals reflected by said plurality of wireless communications device to determine the approximate location of said wireless communication devices.

27. The system of claim 26, wherein said receiver is adapted to remove said second modulation from said data signal to form data.

28. The system of claim 26, wherein said receiver further comprises a mixer that mixes said communication signals with said reflected data signals to remove said first modulation from said reflected data signals to form said data signals.

29. The system of claim 28, wherein said receiver further comprises a demodulator that demodulates said second modulation from said data signals to form data.

30. The system of claim 26, wherein said receiver chooses a frequency hopping sequence that correlates to said frequency hopping sequence used by a chosen one of said transmitters to receive said reflected data signals from one of said wireless communication devices in the field of view of said chosen one of said transmitter.

31. The system of claim 26, wherein said receiver is further adapted to receive said communication signals from said plurality of transmitters and compare said communication signals to the received delay of said reflected data signals to determine the distance between said wireless communication devices and said plurality of transmitters.

32. The system of claim 31, wherein said receiver is further adapted to determine the exact location of said wireless communication devices by triangulating at least two different communication signals to the received delay of one of said reflected data signals.

33. A method of communicating a data signal from a wireless communication device using an incident radio signal from a transmitter as a communication medium, comprising the steps of:

transmitting an incident radio signal having a modulation to a wireless communication device;

reflectively modulating said incident radio signal with a data signal having a second modulation to form a reflected data signal;

receiving said reflected data signal and said incident radio signal at a receiver; and

removing said incident radio signal from said reflected data signal to form said data signal.

34. The method of claim 33, further comprising removing said second modulation from said data signal to form data.

35. The method of claim 33, wherein said removing said incident radio signal from said reflected data signal comprises mixing said incident radio signal with said reflected data signal.

36. The method of claim 34, wherein said removing said second modulation comprises demodulating said second modulation from said data signal.

37. The method of claim 33, wherein said transmitting said incident radio signal comprises spreading said incident radio signal by mixing a spread spectrum code from a spread spectrum coding sequence with said incident radio signal and transmitting said incident radio signal in spread format.

38. The method of claim 37, further comprising correlating a receiver spread spectrum code from said spread spectrum coding sequence to said spread spectrum code in said reflected data signal to recover said reflected data signal in unspread format.

39. The method of claim 33, further comprising mixing a spread spectrum code with said incident radio signal and transmitting said incident radio signal in spread format.

40. The method of claim 39, further comprising choosing a receiver spread spectrum code that correlates to said spread spectrum code used by a chosen one of said transmitters to receive said reflected data signals from said wireless communication devices in the field of view of said chosen one of said transmitters.

41. A method of reflectively communicating a data signal from a wireless communication device using a communication signal from a transmitter as a communication medium, comprising the steps of:

transmitting communication signals having a first modulation through a plurality of openings in a cable to a plurality of reflectors;

receiving said communication signals;

reflectively modulating said communication signals with data signals having a second modulation to form reflected data signals; and

receiving said reflected data signals at a receiver.

42. The method of claim 41, further comprising removing said second modulation from said data signal to form data.

43. The method of claim 41, further comprising mixing said communication signal with said reflected data signal to remove said first modulation from said reflected data signal to form said data signal.

44. The system of claim 43, further comprising demodulating said second modulation from said data signal to form data.

45. The method of claim 41, further comprising determining the approximate location of said wireless communication device that reflected said reflected data signal by determining the delay in said reflected data signal.

46. A method of determining the origination of a data signal reflected by a wireless communication device using a communication signal from a transmitter as a communication medium, comprising:

transmitting communication signals having modulation at the same frequency and each with different spread spectrum codes at plurality of transmitters;

reflectively modulating said communication signals with data signals to form reflected data signals at wireless communication devices;

receiving said reflected data signals at a receiver; and

determining which particular one transmitter in said plurality of transmitters originated a particular one of said reflected data signals by correlating the spread spectrum code in said one of said reflected data signal.

47. The method of claim 46, further comprising removing said second modulation from said data signals to form data.

48. The method of claim 46, further comprising mixing said communication signals with said reflected data signals to remove said first modulation from said reflected data signals to form said data signals.

49. The method of claim 48, further comprising demodulating said second modulation from said data signals to form data.

50. The method of claim 46, further comprising correlating and mixing a receiver spread spectrum code from said spread spectrum coding sequence to said spread spectrum code in said reflected data signals to recover said reflected data signals in unspread format.

51. The method of claim 46, further comprising choosing a receiver spread spectrum code that correlates to the spread spectrum code used by a chosen one of said transmitters to receive said reflected data signals from one of said wireless communication devices in the field of view of said chosen one of said transmitters.

52. The method of claim 46, further comprising receiving said communication signals from a chosen one of said plurality of transmitters and comparing said communication signals to the received delay of said reflected data signals to determine the distance between said wireless communication devices and said chosen one of said plurality of transmitters.

53. The method of claim 52, further comprising determining the exact location of said wireless communication devices by triangulating at least two different communication signals to the received delay of one of said reflected data signals.