Methods for using a detector to monitor and detect channel occupancy

• US 8,027,249 B2
• Filed: 10/18/2006
• Issued: 09/27/2011
• Est. Priority Date: 10/18/2006
• Status: Expired due to Fees

• Current Assignee: Shared Spectrum Company
• Original Assignee: Shared Spectrum Company
• Inventors: Livsics, Jevgenijs, Steadman, Karl, Dain, Dmitry, McHenry, Mark A., Ritterbush, Olga
• Primary Examiner(s): Jain; Raj K
• Application Number:
  US11/582,496
• Publication Number:
  US 20080095042A1
• Time in Patent Office: 1,805 Days
• Field of Search: None
• US Class Current: 370/221
• CPC Class Codes: H04B 17/14 of the whole transmission and reception path, e.g. self-test loop-back
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04B 7/0647 Variable feedback rate
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 56/00 Synchronisation arrangements
• CPC Class Codes: H04W 56/002 Mutual synchronization
• CPC Class Codes: H04W 56/003 Arrangements to increase tolerance to errors in transmission or reception timing
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 74/0816 with collision avoidance

Abstract

Methods for using a detector to monitor and detect channel occupancy are disclosed. The detector resides on a station within a network using a framed format having a periodic time structure. When non-cooperative transmissions are detected by the network, the detector assesses the availability of a backup channel enabling migration of the network. The backup channel serves to allow the network to migrate transparently when the current channel becomes unavailable. The backup channel, however, could be occupied by another network that results in the migrating network interfering with the network already using the backup channel. Thus, the detector detects active transmission sources on the backup channel to determine whether the backup channel is occupied. Methods for using the detector include scheduling detection intervals asynchronously. The asynchronous detection uses offsets from a reference point within a frame.

Claims

1. A method comprising:

providing a network station having a receiver and a wireless spectrum detector separate from the receiver;

identifying, with the wireless spectrum detector, a framing of a cooperative network transmission on a first frequency;

scheduling an asynchronous detection interval having a reference within a frame defined by the identified framing of the cooperative network;

detecting, with the wireless spectrum detector, for non-cooperative transmissions on the first frequency, the non-cooperative transmissions originating from a source not participating in the cooperative network;

detecting, with the wireless spectrum detector, for non-cooperative transmissions on a second frequency during the scheduled asynchronous detection interval;

determining that the first frequency is occupied based upon a presence of a non-cooperative transmission detected by the wireless spectrum detector on the first frequency;

determining that the second frequency is not occupied based upon an absence of non-cooperative transmissions detected by the wireless spectrum detector on the second frequency;

tuning the receiver to the second frequency responsive to information received from the wireless spectrum detector regarding occupancy of the first and second frequencies; and

receiving, with the receiver, a transmission from a cooperative network station on the second frequency.

2. The method of claim 1, wherein the reference includes a transmission gap within the frame.

3. The method of claim 2, further comprising the step of scheduling the transmission gap for each of a plurality of stations in the network.

4. The method of claim 1, wherein the step of scheduling includes scheduling a start of the detection interval using a first offset from the reference within the frame.

5. The method of claim 4, wherein the offset is derived in a predetermined manner.

6. The method of claim 4, wherein the scheduling includes determining a second start of a detection interval using a second offset from the reference within the frame, wherein the second offset is selected from a plurality of precomputed or preselected offsets.

7. The method of claim 6, wherein the first offset differs from the second offset.

8. The method of claim 4, wherein said step of scheduling comprises:

determining a second start of a second detection interval using a second offset from the reference within the frame, the second detection interval being longer than the scheduled asynchronous detection interval; and

determining a third start of a third detection interval using a third offset from the reference within the frame, the third detection interval being longer than the second detection interval.

9. The method of claim 1, wherein the scheduling includes scheduling the detection interval using a random offset from the reference within the frame.

10. The method of claim 1, wherein the non-cooperative transmissions originate from a source that is not capable of participating in the cooperative network.

11. The method of claim 1, wherein the network station and the source of the non-cooperative transmissions are not in communication with any common network station.

12. A method comprising:

providing a network station having a receiver and a wireless spectrum detector separate from the receiver;

identifying the framing of a cooperative network transmission on a first frequency using the wireless spectrum detector;

detecting for non-cooperative transmissions on the first frequency using the wireless spectrum detector, the non-cooperative transmissions originating from a source not participating in the network, wherein the network uses a current channel that includes the first frequency;

detecting for non-cooperative transmissions on a backup channel that includes a second frequency different from the first frequency of the current channel using the wireless spectrum detector;

determining that the first frequency is occupied based upon a presence of a non-cooperative transmission detected by the detector on the first frequency;

determining that the second frequency is not occupied based upon an absence of non-cooperative transmissions detected by the detector on the second frequency;

tuning the receiver to the second frequency responsive to information received from the detector regarding occupancy of the first and second frequencies; and

receiving a transmission from a cooperative network station on the second frequency using the receiver.

13. The method of claim 12, further comprising using the wireless spectrum detector to detect non-cooperative transmissions on the second frequency.

14. The method of claim 12, further comprising the step of scheduling the start of the detection interval for each of a plurality of stations in the network.

15. A method for using a detector, the method comprising:

detecting non-cooperative transmissions on a first channel at a first station participating in a cooperative network, the non-cooperative transmissions originating from a source not participating in the cooperative network;

scheduling a start of a detection interval;

detecting non-cooperative transmissions on a second channel using the detector during the detection interval; and

receiving a transmission from a second station participating in the cooperative network at the first station during the detection interval.

16. The method of claim 15, wherein the detection interval is scheduled using a random offset within a frame.

17. The method of claim 16, further comprising randomly scheduling another start of a detection period with another random offset.

18. A method for using a detector to determine availability of a backup channel, the method comprising:

detecting non-cooperative transmissions on a current channel used for communication among a plurality of network stations in a cooperative network at a station participating in the cooperative network, wherein the current channel uses a frequency within a detector window of the detector and wherein a backup channel is not at a frequency simultaneously observable by the detector;

scheduling a detection interval within a portion of a frame not used to receive network transmissions;

buffering information to be transmitted during the portion of the frame if the detection interval is scheduled during a station transmission interval;

tuning a station having the detector to a backup frequency included in the backup channel, wherein the backup channel is within the detector window; and

detecting non-cooperative transmissions on the backup channel using the detector during the detection interval, the non-cooperative transmissions originating from a source not participating in the network.

19. The method of claim 18, further comprising indicating the backup channel is occupied based on the second detecting step.

20. The method of claim 18, wherein the scheduling step includes scheduling a start of the detection interval using an offset from a reference point within the frame.

21. A method comprising:

providing a network station having a receiver and a wireless spectrum detector separate from the receiver;

identifying, with the wireless spectrum detector, a framing of a cooperative network transmission on a first frequency;

scheduling a transmission gap within a frame defined by the framing of the cooperative network, during which each of the network stations in the cooperative network refrains from transmitting;

scheduling an asynchronous detection interval within the frame defined by the identified framing of the cooperative network, the asynchronous detection interval not overlapping with the transmission gap within the frame;

detecting, with the wireless spectrum detector, for non-cooperative transmissions on a second frequency during the transmission gap, the non-cooperative transmissions originating from a source not participating in the cooperative network;

detecting, with the wireless spectrum detector, for non-cooperative transmissions on the second frequency during the asynchronous detection interval, the asynchronous detection interval not overlapping with the transmission gap within the frame;

determining that the first frequency is occupied based upon a presence of a non-cooperative transmission detected by the wireless spectrum detector on the first frequency;

determining that the second frequency is not occupied based upon an absence of non-cooperative transmissions detected by the wireless spectrum detector on the second frequency; and

receiving, with the receiver, a transmission from a cooperative network station on the second frequency subsequent to migrating the cooperative network from the first frequency to the second frequency.

22. The method of claim 21, further comprising:

detecting, with the wireless spectrum detector, for the presence of non-cooperative transmissions on the first frequency during the transmission gap.

23. The method of claim 21, further comprising

detecting, with the wireless spectrum detector, for the presence of non-cooperative transmissions on the first frequency during the asynchronous detection interval.

24. A system comprising:

a plurality of network stations, at least one of said network stations comprising a detector and a receiver separate from the detector, said at least one network station configured to perform a method comprising;

identifying the framing of a cooperative network transmission on a first frequency using the wireless spectrum detector;

detecting for non-cooperative transmissions on the first frequency using the wireless spectrum detector, the non-cooperative transmissions originating from a source not participating in the network, wherein the network uses a current channel that includes the first frequency;

detecting for non-cooperative transmissions on a backup channel that includes a second frequency different from the first frequency of the current channel using the wireless spectrum detector;

determining that the first frequency is occupied based upon a presence of a non-cooperative transmission detected by the detector on the first frequency;

determining that the second frequency is not occupied based upon an absence of non-cooperative transmissions detected by the detector on the second frequency;

tuning the receiver to the second frequency responsive to information received from the detector regarding occupancy of the first and second frequencies; and

receiving a transmission from a cooperative network station on the second frequency using the receiver.

25. The system of claim 24, said method further comprising using the wireless spectrum detector to detect non-cooperative transmissions on the second frequency.

26. The system of claim 24, said method further comprising the step of scheduling the start of the detection interval for each of a plurality of stations in the network.

27. A device comprising:

a wireless spectrum detector configured to detect a framing of a cooperative network transmission on a first frequency and to detect for non-cooperative transmissions on the first frequency, the non-cooperative transmissions originating from a source not participating in the cooperative network;

a processor configured to schedule an asynchronous detection interval having a reference within a frame defined by the framing of the cooperative network; and

a receiver configured to tune to a second frequency responsive to information received from the wireless spectrum detector and to receive a transmission from a cooperative network station on the second frequency;

said detector further configured to detect for non-cooperative transmissions a the second frequency during the scheduled asynchronous detection interval;

said processor configured to determine that the first frequency is occupied based upon a presence of a non-cooperative transmission detected by the wireless spectrum detector on the first frequency, and to determine that the second frequency is not occupied based upon an absence of non-cooperative transmissions detected by the wireless spectrum detector on the second frequency.

28. The device of claim 27, wherein the reference includes a transmission gap within the frame.

29. The device of claim 28, said processor further configured to schedule the transmission gap for each of a plurality of stations in the network.

30. The device of claim 27, said processor further configured to schedule a start of the detection interval using a first offset from the reference within the frame.

31. The device of claim 30, wherein the offset is derived in a predetermined manner.

32. The device of claim 30, said processor further configured to determine a second start of a detection interval using a second offset from the reference within the frame, wherein the second offset is selected from a plurality of precomputed or preselected offsets.

33. The device of claim 30, wherein said step of scheduling comprises:

determining a second start of a second detection interval using a second offset from the reference within the frame, the second detection interval being longer than the scheduled asynchronous detection interval; and

determining a third start of a third detection interval using a third offset from the reference within the frame, the third detection interval being longer than the second detection interval.

34. The device of claim 33, wherein the first offset differs from the second offset.

35. The device of claim 27, said processor further configured to schedule the detection interval using a random offset from the reference within the frame.

36. The device of claim 27, wherein the non-cooperative transmissions originate from a source that is not capable of participating in the cooperative network.

37. The device of claim 27, wherein the device and the source of the non-cooperative transmissions are not in communication with any common network station.

40. The system of claim 28, said processor further configured to schedule the transmission gap for each of a plurality of stations in the network.

38. A system comprising:

a plurality of network stations, at least one of said plurality of network stations further comprising;

a wireless spectrum detector configured to detect a framing of a cooperative network transmission on a first frequency and to detect for non-cooperative transmissions on the first frequency, the non-cooperative transmissions originating from a source not participating in the cooperative network;

a processor configured to schedule an asynchronous detection interval having a reference within a frame defined by the framing of the cooperative network; and

a receiver configured to tune to a second frequency responsive to information received from the wireless spectrum detector and to receive a transmission from a cooperative network station on the second frequency;

said detector further configured to detect for non-cooperative transmissions a the second frequency during the scheduled asynchronous detection interval;

said processor configured to determine that the first frequency is occupied based upon a presence of a non-cooperative transmission detected by the wireless spectrum detector on the first frequency, and to determine that the second frequency is not occupied based upon an absence of non-cooperative transmissions detected by the wireless spectrum detector on the second frequency.

39. The system of claim 38, wherein the reference includes a transmission gap within the frame.

41. The system of claim 38, said processor further configured to schedule a start of the detection interval using a first offset from the reference within the frame.

42. The system of claim 41, wherein the offset is derived in a predetermined manner.

43. The system of claim 41, said processor further configured to determine a second start of a detection interval using a second offset from the reference within the frame, wherein the second offset is selected from a plurality of precomputed or preselected offsets.

44. The system of claim 41, wherein said step of scheduling comprises:

determining a second start of a second detection interval using a second offset from the reference within the frame, the second detection interval being longer than the scheduled asynchronous detection interval; and

determining a third start of a third detection interval using a third offset from the reference within the frame, the third detection interval being longer than the second detection interval.

45. The system of claim 44, wherein the first offset differs from the second offset.

46. The system of claim 38, said processor further configured to schedule the detection interval using a random offset from the reference within the frame.

47. The system of claim 38, wherein the non-cooperative transmissions originate from a source that is not capable of participating in the cooperative network.

48. The system of claim 38, wherein said at least one of said plurality of network stations and the source of the non-cooperative transmissions are not in communication with any common network station.

49. A device comprising:

a detector configured to;

identify a framing of a cooperative network transmission on a first frequency;

detect for non-cooperative transmissions on the first frequency, the non-cooperative transmissions originating from a source not participating in the network, wherein the network uses a current channel that includes the first frequency; and

detect for non-cooperative transmissions on a backup channel that includes a second frequency different from the first frequency of the current channel;

a receiver, separate from the detector, configured to receive a transmission from a cooperative network station on the second frequency; and

a processor configured to;

determine that the first frequency is occupied based upon a presence of a non-cooperative transmission detected by the detector on the first frequency;

determine that the second frequency is not occupied based upon an absence of non-cooperative transmissions detected by the detector on the second frequency; and

tune the receiver to the second frequency responsive to information received from the detector regarding occupancy of the first and second frequencies.

50. The device of claim 49, said detector further configured to detect non-cooperative transmissions on the second frequency.

51. The device of claim 49, said processor further configured to schedule the start of the detection interval for each of a plurality of stations in the network.

52. A device configured to participate in a cooperative network, said device comprising:

a detector configured to;

detect non-cooperative transmissions on a first channel, the non-cooperative transmissions originating from a source not participating in the cooperative network; and

detect non-cooperative transmissions on a second channel during a detection interval;

a processor configured to scheduling a start of the detection interval; and

a receiver configured to receive a transmission from another station participating in the cooperative network during the detection interval.

53. The device of claim 52, wherein the detection interval is scheduled using a random offset within a frame.

54. The device of claim 53, said processor further configured to randomly schedule another start of a detection period with another random offset.

55. A system comprising:

a plurality of network stations participating in a cooperative network, at least one of said plurality of network stations comprising a detector and configured to perform a method comprising;

detecting non-cooperative transmissions on a first channel at said at least one of said plurality of network stations, the non-cooperative transmissions originating from a source not participating in the cooperative network;

scheduling a start of a detection interval;

detecting non-cooperative transmissions on a second channel using the detector during the detection interval; and

receiving a transmission from a second station participating in the cooperative network during the detection interval.

56. The system of claim 55, wherein the detection interval is scheduled using a random offset within a frame.

57. The system of claim 56, said at least one of said plurality of network stations further configured to randomly schedule another start of a detection period with another random offset.

58. A device comprising a detector, said device configured to perform a method comprising:

detecting non-cooperative transmissions on a current channel used for communication among a plurality of network stations in a cooperative network at a station participating in the cooperative network, wherein the current channel uses a frequency within a detector window of the detector and wherein a backup channel is not at a frequency simultaneously observable by the detector;

scheduling a detection interval within a portion of a frame not used to receive network transmissions;

buffering information to be transmitted during the portion of the frame if the detection interval is scheduled during a station transmission interval;

tuning the device to a backup frequency included in the backup channel, wherein the backup channel is within the detector window; and

detecting non-cooperative transmissions on the backup channel using the detector during the detection interval, the non-cooperative transmissions originating from a source not participating in the network.

59. The device of claim 58, further configured to indicate the backup channel is occupied based on the second detecting step.

60. The device of claim 58, wherein the scheduling step includes scheduling a start of the detection interval using an offset from a reference point within the frame.

61. A system comprising:

a plurality of network stations configured to communicate in a cooperative network, at least one of said plurality of network stations comprising a detector and configured to perform a method comprising;

detecting non-cooperative transmissions on a current channel used for communication among said plurality of network stations at said at least one of said plurality of network stations, wherein the current channel uses a frequency within a detector window of the detector and wherein a backup channel is not at a frequency simultaneously observable by the detector;

scheduling a detection interval within a portion of a frame not used to receive network transmissions;

buffering information to be transmitted during the portion of the frame if the detection interval is scheduled during a station transmission interval;

tuning the at least one of said plurality of network stations to a backup frequency included in the backup channel, wherein the backup channel is within the detector window; and

detecting non-cooperative transmissions on the backup channel using the detector during the detection interval, the non-cooperative transmissions originating from a source not participating in the network.

62. The system of claim 61, at least one of said plurality of network stations configured to indicate the backup channel is occupied based on the second detecting step.

63. The system of claim 61, wherein the scheduling step includes scheduling a start of the detection interval using an offset from a reference point within the frame.

64. A device comprising:

a receiver; and

a wireless spectrum detector separate from the receiver,

said device configured to;

identify, with the wireless spectrum detector, a framing of a cooperative network transmission on a first frequency;

schedule a transmission gap within a frame defined by the framing of the cooperative network, during which each of the network stations in the cooperative network refrains from transmitting;

schedule an asynchronous detection interval within the frame defined by the identified framing of the cooperative network, the asynchronous detection interval not overlapping with the transmission gap within the frame;

detect, with the wireless spectrum detector, for non-cooperative transmissions on a second frequency during the transmission gap, the non-cooperative transmissions originating from a source not participating in the cooperative network;

detect, with the wireless spectrum detector, for non-cooperative transmissions on the second frequency during the asynchronous detection interval, the asynchronous detection interval not overlapping with the transmission gap within the frame;

determine that the first frequency is occupied based upon a presence of a non-cooperative transmission detected by the wireless spectrum detector on the first frequency;

determine that the second frequency is not occupied based upon an absence of non-cooperative transmissions detected by the wireless spectrum detector on the second frequency; and

receive, with the receiver, a transmission from a cooperative network station on the second frequency subsequent to migrating the cooperative network from the first frequency to the second frequency.

65. The device of claim 64, further configured to detect for the presence of non-cooperative transmissions on the first frequency during the transmission gap.

66. The device of claim 64, further configured to detect for the presence of non-cooperative transmissions on the first frequency during the asynchronous detection interval.

67. A system comprising:

a plurality of network stations configured to operate in a cooperative network, at least one of said plurality of network stations comprising a wireless spectrum detector and a receiver, and configured to;

identify, with the wireless spectrum detector, a framing of a cooperative network transmission on a first frequency;

schedule a transmission gap within a frame defined by the framing of the cooperative network, during which each of the network stations in the cooperative network refrains from transmitting;

schedule an asynchronous detection interval within the frame defined by the identified framing of the cooperative network, the asynchronous detection interval not overlapping with the transmission gap within the frame;

detect, with the wireless spectrum detector, for non-cooperative transmissions on a second frequency during the transmission gap, the non-cooperative transmissions originating from a source not participating in the cooperative network;

detect, with the wireless spectrum detector, for non-cooperative transmissions on the second frequency during the asynchronous detection interval, the asynchronous detection interval not overlapping with the transmission gap within the frame;

determine that the first frequency is occupied based upon a presence of a non-cooperative transmission detected by the wireless spectrum detector on the first frequency;

determine that the second frequency is not occupied based upon an absence of non-cooperative transmissions detected by the wireless spectrum detector on the second frequency; and

receive, with the receiver, a transmission from a cooperative network station on the second frequency subsequent to migrating the cooperative network from the first frequency to the second frequency.

68. The system of claim 67, at least one of said plurality of network stations configured to detect for the presence of non-cooperative transmissions on the first frequency during the transmission gap.

69. The system of claim 67, at least one of said plurality of network stations configured to detect for the presence of non-cooperative transmissions on the first frequency during the asynchronous detection interval.