Cancellation system and method for a wireless positioning system

• US 20050037724A1
• Filed: 06/16/2004
• Published: 02/17/2005
• Est. Priority Date: 05/02/2000
• Status: Active Grant

• Current Assignee: CSR Technology Incorporated (Qualcomm, Inc.)
• Original Assignee: CSR Technology Incorporated (Qualcomm, Inc.)
• Inventors: Gronemeyer, Steven A., Walley, Kenneth Scott, Underbrink, Paul A.
• Granted Patent: US 7,983,666 B2
• Time in Patent Office: Days
• US Class Current: 455/302
• CPC Class Codes: G01S 19/21 Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service
• CPC Class Codes: H04B 1/71075 Parallel interference cancellation

Abstract

A cancellation system may utilize a system architecture that delays the received signals and cancels less than all the received signals from the delayed version of the received signals. An implementation of this system architecture may include a delay circuit, a demodulation and despreader unit, a re-modulator and re-spreader unit and a combiner. The delay circuit produces a delayed version of the received signals and the demodulator and de-spreader unit produces a demodulated and de-spread signal corresponding to one of the received signals. The respreader and remodulator unit produces a remodulated and respread signal from the demodulated and despread signal and the combiner produces a combined signal from the delayed version of the received signals and the remodulated and respread signal. The cancellation system may also utilize a system architecture that stores the received signals and cancels less than all the received signals from the stored version of the received signals. An implementation of this system architecture may include a matched filter, a storage unit, a remodulator and respreader unit, and a combiner. The storage unit stores the received signals and the matched filter produces a demodulated and despread signal corresponding to one of the received signals. The remodulator and respreader unit produces a remodulated and respread signal from the output of the matched filter and the combiner produces a combined signal from the output of the storage unit and the remodulated and respread signal.

Claims

1. A method for detecting low power signals from a plurality of received signals, the method comprising:

delaying the plurality of received signals;

canceling less than the entire plurality of received signals from the delayed plurality of received signals to create a resultant signal; and

detecting at least one lower power signal from the resultant signal.

2. The method of claim 1 further includes calculating a geographic position for a wireless device from the resultant signal.

3. The method of claim 1 wherein the step of canceling further includes:

obtaining a processed signal from the plurality of received signals; and

combining the processed signal with the delayed plurality of received signals.

4. The method of claim 3 wherein the step of obtaining further includes:

demodulating the plurality of received signals to created a demodulated signal; and

despreading the demodulated signal to create the processed signal.

5. The method of claim 4 wherein the step of combining further includes:

respreading the processed signal to create a respread signal;

remodulating the respread signal to create a respread and remodulated signal; and

subtracting the respread and remodulated signal from the delayed plurality of received signals.

6. The method of claim 5 further includes calculating a geographic position for a wireless device from the result of subtracting the respread and remodulated signal from the delayed plurality of received signals.

7. A method for detecting low power signals from a plurality of received signals, the method comprising:

storing the plurality of received signals;

canceling less than the entire plurality of received signals from the stored plurality of received signals to create a resultant signal; and

detecting the at least one lower power signal from the resultant signal.

8. The method of claim 7 further includes calculating a geographic position for a wireless device from the resultant signal.

9. The method of claim 7 wherein the step of canceling further includes:

obtaining a processed signal from the plurality of received signals; and

combining the processed signal with the stored plurality of received signals.

10. The method of claim 9 wherein the step of obtaining further includes match filtering the plurality of received signals to create the processed signal.

11. The method of claim 10 wherein the step of combining further includes:

respreading the processed signal to create a respread signal;

remodulating the respread signal to create a respread and remodulated signal; and

subtracting the respread and remodulated signal from the stored plurality of received signals.

12. The method of claim 11 further including calculating a geographic position for a wireless device from the result of subtracting the respread and remodulated signal from the stored plurality of received signals.

13. A cancellation system for detecting low power signals from a plurality of received signals, the cancellation system comprising:

means for delaying the plurality of received signals;

means for canceling less than the entire plurality of received signals from the delayed plurality of received signals to create a resultant signal; and

means for detecting at least one lower power signal from the resultant signal.

14. The cancellation system of claim 13 further including means for calculating a geographic position for a wireless device from the resultant signal.

15. The cancellation system of claim 13 wherein the canceling means further includes:

means for obtaining a processed signal from the plurality of received signals; and

means for combining the processed signal with the delayed plurality of received signals.

16. The cancellation system of claim 15 wherein the obtaining means further includes:

means for demodulating a signal received signal from the plurality of received signals to create a demodulated signal; and

means for despreading the demodulated signal to create the processed signal.

17. The cancellation system of claim 16 wherein the combining means further includes:

means for respreading the processed signal to create a respread signal;

means for remodulating the respread signal to create a respread and remodulated signal; and

means for subtracting the respread and, remodulated signal from the delayed plurality of received signals.

18. A cancellation system for detecting low power signals from a plurality of received signals, the cancellation system comprising:

means for storing the plurality of received signals;

means for canceling less than the entire plurality of received signals from the stored plurality of received signals to create a resultant signal; and

means for detecting at least one lower power signal from the resultant signal.

19. The cancellation system of claim 18 wherein the canceling means further includes:

means for obtaining a processed signal from the plurality of received signals; and

means for combining the processed signal with the delayed plurality of received signals.

20. The cancellation system of claim 19 wherein the obtaining means further includes means for match filtering the plurality of received signals to create the processed signal.

21. The cancellation system of claim 20 wherein the combining means further includes:

means for respreading the processed signal to create a respread signal;

means for remodulating the respread signal to create a respread and remodulated signal; and

means for subtracting the respread and remodulated signal from the stored plurality of received signals.

22. The cancellation system of claim 21 further including means for calculating a geographic position for a wireless device from the resultant signal.

23. A cancellation system for detecting low power signals from a plurality of received signals, the cancellation system comprising:

a delay circuit;

a demodulator and despreader unit that produces a demodulated and despread signal corresponding to one of the plurality of received signals;

a remodulator and respreader unit in signal communication with the demodulator and despreader unit, the remodulator and respreader unit produces a respread and remodulated signal from the demodulated and despread signal; and

a combiner in signal communication with the delay circuit and the remodulator and respreader unit, the combiner produces a combined signal from the output of the delay circuit and the respread and remodulated signal.

24. The cancellation system of claim 23 wherein the demodulator and despreader unit further includes:

a carrier demodulator, and

a decoder in signal communication with the carrier demodulator.

25. The cancellation system of claim 24 further includes a data decoder in signal communication with the combiner.

26. The cancellation system of claim 25 further including a processor that utilizes the output of the data decoder to calculate a position of a satellite.

27. The cancellation system of claim 26 wherein the processor also calculates the geographic position of the cancellation system.

28. The cancellation system of claim 24 wherein the combined signal is the difference of the output of the delay circuit and the respread and remodulated signal.

29. A cancellation system for detecting low power signals from a plurality of received signals, the cancellation system comprising:

a matched filter unit;

a storage unit that stores the plurality of received signals;

a remodulator and respreader unit in signal communication with the matched filter unit, the remodulator and respreader unit produces a respread and remodulated signal from the output of the matched filter; and

a combiner in signal communication with the storage unit and the remodulator and respreader unit, the combiner produces a combined signal from the output of the storage unit and the remodulated and respread signal.

30. The cancellation system of claim 29 further includes a data decoder in signal communication with the combiner.

31. The cancellation system of claim 30 further includes a processor that utilizes the data decoder to calculate a position of a satellite.

32. The cancellation system of claim 31 further including a switch in signal communication with the combiner, data decoder, storage unit, and processor.

33. The cancellation system of claim 31 wherein the processor also calculates the geographic position of the cancellation system.

34. The cancellation system of claim 29 wherein the combined signal is the difference of the output of the storage unit and the respread and Demodulated signal.

35. A computer readable medium having software for detecting low power signals from a plurality of received signals for a cancellation system, the software comprising:

logic configured to delay the plurality of received signals;

logic configured to cancel less than the entire plurality of received signals from the delayed plurality of received signals to create a resultant signal; and

logic configured to detect at least one lower power signal from the resultant signal.

36. The computer readable medium of claim 35 further including logic for calculating a geographic position for a wireless device from the resultant signal.

37. The computer readable medium of claim 35 wherein the canceling logic further includes:

logic configured to obtain a processed signal from the plurality of received signals; and

logic configured to combine the processed signal with the delayed plurality of received signals.

38. The computer readable medium 37 wherein the obtaining logic further includes:

logic configured to demodulate the plurality of received signals to create a demodulated signal; and

logic configured to despread the demodulated signal to create the processed signal.

39. The computer readable medium of claim 38 wherein the combining logic further includes:

logic configured to respread the processed signal to create a respread signal;

logic configured to remodulate the respread signal to create a respread and remodulated signal; and

logic configured to subtract the respread and remodulated signal from the delayed plurality of received signals.

40. A computer readable medium having software for detecting low power signals from a plurality of received signals for a cancellation system, the software comprising:

logic configured to store the plurality of received signals;

logic configured to cancel less than the entire plurality of received signals from the stored plurality of received signals to create a resultant signal; and

logic configured to detect at least one lower power signal from the resultant signal.

41. The computer readable medium of claim 40 further including logic for calculating a geographic position for a wireless device from the resultant signal.

42. The computer readable medium of claim 40 wherein the canceling logic further includes:

logic configured to obtain a processed signal from the plurality of received signals; and

logic configured to combine the processed signal with the stored plurality of received signals.

43. The computer readable medium of claim 42 wherein the obtaining logic further includes logic configured to match filter the received signal from the plurality of received signals to create a processed signal.

44. The computer readable medium of claim 43 wherein the combining logic further includes:

logic configured to respread the processed signal to create a respread signal;

logic configured to remodulate the respread signal so as to create a respread and remodulated signal; and

logic configured to subtract the respread and remodulated signal from the stored plurality of received signals.

45. A computer data signal embodied in a carrier wave for detecting low power signals from a plurality of received signals for a cancellation system, the computer data signal comprising:

a receiving source code segment comprising logic configured to delay the plurality of received signals;

a processing source code segment comprising;

logic configured to cancel less than the entire plurality of received signals from the delayed plurality of received signals to create a resultant signal, and

logic configured to detect at least one lower power signal from the resultant signal.

46. The computer data signal of claim 45 wherein the canceling logic further includes

logic configured to obtain a processed signal from the plurality of received signals;

and

logic configured to combine the processed signal with the delayed plurality of received signals.

47. The computer data signal of claim 46 wherein the obtaining logic further includes:

logic configured to demodulate the plurality of received signals to create a demodulated signal; and

logic configured to despread the demodulated signal to create the processed signal.

48. The computer data signal of claim 47 wherein the combining logic further includes:

logic configured to respread the processed signal to create a respread signal;

logic configured to remodulate the respread signal to create a respread and remodulated signal; and

logic configured to subtract the respread and remodulated signal from the delayed plurality of received signals.

49. The computer data signal of claim 48 further including logic configured to calculate a geographic position for a wireless device from the result of the subtracting logic.

50. A computer data signal embodied in a carrier wave for detecting low power signals from a plurality of received signals for a cancellation system, the computer data signal comprising:

a receiving source code segment comprising logic configured to store the plurality of received signals; and

a processing source code segment comprising;

logic configured to cancel less than the entire plurality of received signals from the stored plurality of received signals to create a resultant signal, and

logic configured to detect at least one lower power signal from the resultant signal.

51. The computer data signal of claim 50 wherein the canceling logic further includes:

logic configured to obtain a processed signal from the plurality of received signals; and

logic configured to combine the processed signal with the stored plurality of received signals.

52. The computer data signal of claim 51 wherein the obtaining logic further includes logic configured to match filter the plurality of received signals to create the processed signal.

53. The computer data signal of claim 52 wherein the combining logic further includes:

logic configured to respread the processed signal to create a respread signal;

logic configured to remodulate the respread signal to create a respread and remodulated signal; and

logic configured to subtract the respread and remodulated signal from the stored plurality of received signals.

54. The computer data signal of claim 53 further including logic configured to calculate a geographic position for a wireless device from the result of the subtracting logic.

55. A method for detecting low power signals from a plurality of received signals at a mobile device with the assistance of a base station, the method comprising:

receiving at the mobile device a record of the plurality of received signals from the base station; and

detecting the low power signals from the record.

56. The method of claim 55 wherein the step of detecting further includes:

delaying the plurality of received signals;

canceling less than the entire plurality of received signals from the delayed plurality of received signals based on the record to create a resultant signal; and

detecting at least one lower power signal from the resultant signal.

57. The method of claim 56 wherein the step of canceling further includes:

obtaining a processed signal from the plurality of received signals based on the record; and

combining the processed signal with the delayed plurality of received signals.

58. The method of claim 57 wherein the step of obtaining further includes:

demodulating the plurality of received signals to created a demodulated signal; and

despreading the demodulated signal to create the processed signal.

59. The method of claim 58 wherein the step of combining further includes:

respreading the processed signal to create a respread signal;

remodulating the respread signal to create a respread and remodulated signal; and

subtracting the respread and remodulated signal from the delayed plurality of received signals.

60. The method of claim 59 further includes calculating a geographic position for the mobile device from the result of subtracting the respread and remodulated signal from the delayed plurality of received signals.

61. The method of claim 55 wherein the step of detecting further includes:

storing the plurality of received signals;

canceling less than the entire plurality of received signals from the stored plurality of received signals based on the record to create a resultant signal; and

detecting the at least one lower power signal from the resultant signal.

62. The method of claim 61 further includes calculating a geographic position for a wireless device from the resultant signal.

63. The method of claim 62 wherein the step of canceling further includes:

obtaining a processed signal from the plurality of received signals based on the record; and

combining the processed signal with the stored plurality of received signals.

64. The method of claim 63 wherein the step of obtaining further includes match filtering the plurality of received signals to create the processed signal.

65. The method of claim 64 wherein the step of combining further includes:

respreading the processed signal to create a respread signal;

remodulating the respread signal to create a respread and remodulated signal; and

subtracting the respread and remodulated signal from the stored plurality of received signals.

66. The method of claim 65 further including calculating a geographic position for a wireless device from the result of subtracting the respread and remodulated signal from the stored plurality of received signals.

67. A method for detecting low power signals from a plurality of received signals at a mobile device with the assistance of a base station, based on measuring time related to satellite data messages for use with a satellite positioning system, the method comprising:

receiving at a mobile device a first record of at least a portion of a satellite data message;

comparing the first record with a second record of the satellite data message received at a base station wherein the first record and the second record overlap at least partially in time;

determining a time for the comparing step, the time indicating when the first record was received at the mobile device; and

detecting the at least one lower power signal at the mobile device based on the time.

68. The method of claim 67 wherein the step of detecting further includes:

delaying the plurality of received signals;

canceling less than the entire plurality of received signals from the delayed plurality of received signals based on the time to create a resultant signal; and

detecting at least one lower power signal from the resultant signal.

69. The method of claim 68 wherein the step of canceling further includes:

obtaining a processed signal from the plurality of received signals based on the time; and

combining the processed signal with the delayed plurality of received signals.

70. A method for measuring time related to satellite data messages for use with a satellite positioning system, the method comprising:

receiving in a mobile satellite positioning system receiver at least a portion of a satellite data message;

determining a first record of the at least a portion of the satellite data message;

transmitting from the mobile satellite positioning system receiver the first record to a remote base station for the purpose of determining a time indicating when the first record was received at the mobile satellite positioning system receiver.