Autonomous adaptation of transmit power

• US 8,712,461 B2
• Filed: 08/06/2008
• Issued: 04/29/2014
• Est. Priority Date: 08/10/2007
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Yavuz, Mehmet, Black, Peter J., Nanda, Sanjiv
• Primary Examiner(s): Alam, Fayyaz
• Application Number:
  US12/187,310
• Publication Number:
  US 20090042595A1
• Time in Patent Office: 2,092 Days
• Field of Search: 455/522, 455 69- 70, 370318-320
• US Class Current: 455/522
• CPC Class Codes: H04W 16/16 for PBS [Private Base Station] arrangements
• CPC Class Codes: H04W 36/04 Reselecting a cell layer in multi-layered cells
• CPC Class Codes: H04W 52/143 Downlink power control
• CPC Class Codes: H04W 52/244 Interferences in heterogeneous networks, e.g. among macro and femto or pico cells or other sector / system interference [OSI]
• CPC Class Codes: H04W 52/245 taking into account received signal strength
• CPC Class Codes: H04W 52/367 Power values between minimum and maximum limits, e.g. dynamic range
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff

Abstract

Transmit power (e.g., maximum transmit power) may be defined based on the maximum received signal strength allowed by a receiver and a minimum coupling loss from a transmitting node to a receiver. Transmit power may be defined for an access node (e.g., a femto node) such that a corresponding outage created in a cell (e.g., a macro cell) is limited while still providing an acceptable level of coverage for access terminals associated with the access node. An access node may autonomously adjust its transmit power based on channel measurement and a defined coverage hole to mitigate interference. Transmit power may be defined based on channel quality. Transmit power may be defined based on a signal-to-noise ratio at an access terminal. The transmit power of neighboring access nodes also may be controlled by inter-access node signaling.

Claims

1. A method of wireless communication, comprising:

determining, at a base station, a total received signal strength at which transmissions on a channel assigned to a wireless subscriber terminal are received; and

determining a transmit power value based on the determined total received signal strength,

wherein the transmit power value includes a maximum transmission power level at which the base station is permitted to transmit to the wireless subscriber terminal.

2. The method of claim 1, further comprising determining received pilot signal strength associated with a pilot signal from a node, wherein the determination of the transmit power value is further based on the determined received pilot signal strength.

3. The method of claim 2, wherein:

the determination of the received pilot signal strength comprises receiving pilot signals from a plurality of macro base stations, and determining which of the pilot signals has a highest received signal strength; and

the determined received pilot signal strength corresponds to the highest received signal strength.

4. The method of claim 2, wherein the determination of the received pilot signal strength comprises estimating the received pilot signal strength based on the determined total received signal strength.

5. The method of claim 2, wherein:

the determination of the total received signal strength comprises receiving an indication of the total received signal strength from a node; and

the determination of the received pilot signal strength comprises receiving an indication of the received pilot signal strength from the node.

6. The method of claim 2, wherein the determination of the transmit power value further comprises:

determining a maximum amount of interference that a transmission from a first node may induce at a second node without causing a pilot-to-signal ratio for the node to fall below a minimum pilot-to-signal ratio, wherein the determination of the maximum amount of interference is based on the determined total received signal strength and the determined received pilot signal strength; and

determining the transmit power value such that the transmission does not induce a level of interference at the second node that exceeds the maximum amount of interference, wherein the determination of the transmit power value is further based on a path loss associated with a coverage area of the first node.

7. The method of claim 6, wherein the coverage area is associated with a co-channel coverage hole.

8. The method of claim 6, wherein the determination of the transmit power value is further based on an adjacent channel interference rejection value between a first channel for which the transmit power value is determined and a second channel on which the total received signal strength is determined.

9. The method of claim 8, wherein the coverage area is associated with an adjacent-channel coverage hole.

10. The method of claim 2, wherein:

the transmit power value is determined for a first channel; and

the determined total received signal strength is measured on the first channel.

11. The method of claim 2, wherein:

the transmit power value is determined for a first channel; and

the determined total received signal strength is measured on a second channel.

12. The method of claim 2, further comprising determining at least one error associated with the determined total received signal strength and/or the determined received pilot signal strength, wherein the determination of the transmit power value is further based on the at least one error.

13. The method of claim 12, further comprising receiving information from a first node that is authorized for data access at a second node for which the transmit power value is determined, wherein the determination of the at least one error is based on the received information.

14. The method of claim 1, further comprising:

determining whether a node is within a coverage area of an access node for which the transmit power value is determined; and

adjusting the determined transmit power value based on the determination of whether the node is within the coverage area.

15. The method of claim 1, further comprising:

determining whether a first node is within a coverage area of a second node for which the transmit power value is determined; and

determining a path loss between the first and second nodes, wherein the determination of the transmit power value is further based on the path loss.

16. The method of claim 15, wherein:

the first node is not authorized for data access at the second node; and

the determination of path loss comprises estimating path loss based on information received from a third node.

17. The method of claim 1, wherein the transmit power value is determined to maintain a signal-to-noise ratio at a neighboring node to be less than or equal to a defined value.

18. The method of claim 1, wherein:

the transmit power value is determined for a first node;

the method further comprises identifying a second node that is substantially near an edge of a coverage area of the first node;

the method further comprises determining a signal-to-noise ratio associated with the second node based on the determined total received signal strength; and

the transmit power value is determined based on the determined signal-to-noise ratio and a defined maximum signal-to-noise ratio.

19. The method of claim 18, wherein the determination of the signal-to-noise ratio comprises receiving signal-to-noise ratio information from the second node.

20. The method of claim 18, wherein the identification of the second node comprises determining that the second node is substantially near the edge based on a path loss between the first and second nodes.

21. The method of claim 20, wherein the second node is not authorized for data access at the first node.

22. The method of claim 1, wherein the transmit power value is determined to enable operation of a visiting access terminal at a predetermined minimum distance from an access node for which the transmit power value is determined.

23. The method of claim 1, wherein the transmit power value comprises a transmit power value for a common control channel.

24. The method of claim 1, wherein the transmit power value comprises a downlink transmit power value for the base station.

25. The method of claim 1, wherein the transmit power value comprises a maximum transmit power value.

26. The method of claim 1, wherein the transmit power value comprises a first preliminary maximum transmit power value, the method further comprising:

determining at least one other preliminary maximum transmit power value; and

determining a maximum transmit power value based on a minimum of the first and at least one other preliminary maximum transmit power value.

27. The method of claim 1, wherein the transmit power value is determined for a node that is restricted for least one of the group consisting of:

signaling, data access, registration, paging, and service to at least one node.

28. The method of claim 1, wherein the transmit power value is determined for a femto node or a pico node.

29. An apparatus for wireless communication, comprising:

a signal strength determiner configured to determine a total received signal strength at which transmissions on a channel assigned to a wireless subscriber terminal are received; and

a transmit power controller configured to determine a transmit power value based on the determined total received signal strength,

wherein the transmit power value includes a maximum transmission power level at which the apparatus is permitted to transmit to the wireless subscriber terminal.

30. The apparatus of claim 29, further comprising a received pilot strength determiner configured to determine received pilot signal strength associated with a pilot signal from a node, wherein the determination of the transmit power value is further based on the determined received pilot signal strength.

31. The apparatus of claim 30, wherein:

the determination of the received pilot signal strength comprises receiving pilot signals from a plurality of macro base stations, and determining which of the pilot signals has a highest received signal strength; and

the determined received pilot signal strength corresponds to the highest received signal strength.

32. The apparatus of claim 30, wherein the determination of the transmit power value further comprises:

determining a maximum amount of interference that a transmission from a first node may induce at a second node without causing a pilot-to-signal ratio for the node to fall below a minimum pilot-to-signal ratio, wherein the determination of the maximum amount of interference is based on the determined total received signal strength and the determined received pilot signal strength; and

determining the transmit power value such that the transmission does not induce a level of interference at the second node that exceeds the maximum amount of interference, wherein the determination of the transmit power value is further based on a path loss associated with a coverage area of the first node.

33. The apparatus of claim 32, wherein the determination of the transmit power value is further based on an adjacent channel interference rejection value between a first channel for which the transmit power value is determined and a second channel on which the total received signal strength is determined.

34. The apparatus of claim 30, further comprising an error determiner configured to determine at least one error associated with the determined total received signal strength and/or the determined received pilot signal strength, wherein the determination of the transmit power value is further based on the at least one error.

35. The apparatus of claim 29, further comprising:

a node detector configured to determine whether a node is within a coverage area of an access node for which the transmit power value is determined, wherein the transmit power controller is further configured to adjust the determined transmit power value based on the determination of whether the node is within the coverage area.

36. The apparatus of claim 29, wherein the transmit power value is determined to maintain a signal-to-noise ratio at a neighboring node to be less than or equal to a defined value.

37. The apparatus of claim 29, wherein:

the transmit power value is determined for a first node;

the apparatus further comprises a node detector configured to identify a second node that is substantially near an edge of a coverage area of the first node;

the apparatus further comprises a signal-to-noise ratio determiner configured to determine a signal-to-noise ratio associated with the second node based on the determined total received signal strength; and

the transmit power value is determined based on the determined signal-to-noise ratio and a defined maximum signal-to-noise ratio.

38. The apparatus of claim 29, wherein the transmit power value comprises a, transmit power value for a common control channel.

39. The apparatus of claim 29, wherein the transmit power value comprises a maximum transmit power value.

40. The apparatus of claim 29, wherein the transmit power value is determined for a node that is restricted for least one of the group consisting of:

signaling, data access, registration, paging, and service to at least one node.

41. The apparatus of claim 29, wherein the transmit power value is determined for a femto node or a pico node.

42. An apparatus for wireless communication, comprising:

means for determining, at a base station, a total received signal strength at which transmissions on a channel assigned to a wireless subscriber terminal are received; and

means for determining a transmit power value based on the determined total received signal strength,

wherein the transmit power value includes a maximum transmission power level at which the base station is permitted to transmit to the wireless subscriber terminal.

43. The apparatus of claim 42, further comprising means for determining received pilot signal strength associated with a pilot signal from a node, wherein the determination of the transmit power value is further based on the determined received pilot signal strength.

44. The apparatus of claim 43, wherein:

the determination of the received pilot signal strength comprises receiving pilot signals from a plurality of macro base stations, and determining which of the pilot signals has a highest received signal strength; and

the determined received pilot signal strength corresponds to the highest received signal strength.

45. The apparatus of claim 43, wherein the determination of the transmit power value further comprises:

determining a maximum amount of interference that a transmission from a first node may induce at a second node without causing a pilot-to-signal ratio for the node to fall below a minimum pilot-to-signal ratio, wherein the determination of the maximum amount of interference is based on the determined total received signal strength and the determined received pilot signal strength; and

determining the transmit power value such that the transmission does not induce a level of interference at the second node that exceeds the maximum amount of interference, wherein the determination of the transmit power value is further based on a path loss associated with a coverage area of the first node.

46. The apparatus of claim 45, wherein the determination of the transmit power value is further based on an adjacent channel interference rejection value between a first channel for which the transmit power value is determined and a second channel on which the total received signal strength is determined.

47. The apparatus of claim 43, further comprising means for determining at least one error associated with the determined total received signal strength and/or the determined received pilot signal strength, wherein the determination of the transmit power value is further based on the at least one error.

48. The apparatus of claim 42, further comprising:

means for determining whether a node is within a coverage area of an access node for which the transmit power value is determined, wherein the means for determining transmit power is configured to adjust the determined transmit power value based on the determination of whether the node is within the coverage area.

49. The apparatus of claim 42, wherein the transmit power value is determined to maintain a signal-to-noise ratio at a neighboring node to be less than or equal to a defined value.

50. The apparatus of claim 42, wherein:

the transmit power value is determined for a first node;

the apparatus further comprises means for identifying a second node that is substantially near an edge of a coverage area of the first node;

the apparatus further comprises means for determining a signal-to-noise ratio associated with the second node based on the determined total received signal strength; and

the transmit power value is determined based on the determined signal-to-noise ratio and a defined maximum signal-to-noise ratio.

51. The apparatus of claim 42, wherein the transmit power value comprises a transmit power value for a common control channel.

52. The apparatus of claim 42, wherein the transmit power value comprises a maximum transmit power value.

53. The apparatus of claim 42, wherein the transmit power value is determined for a node that is restricted for least one of the group consisting of:

signaling, data access, registration, paging, and service to at least one node.

54. The apparatus of claim 42, wherein the transmit power value is determined for a femto node or a pico node.

55. A non-transitory computer-readable medium containing instructions stored thereon, which, when executed by a base station, cause the base station to

determine a total received signal strength at which transmissions on a channel assigned to a wireless subscriber terminal are received;

and

determine a transmit power value based on the determined total received signal strength,

wherein the transmit power value includes a maximum transmission power level at which the base station is permitted to-transmit to the wireless subscriber terminal.

56. The non-transitory computer-readable medium of claim 55, wherein the non-transitory computer-readable medium further comprises codes for causing the base station to determine received pilot signal strength associated with a pilot signal from a node, wherein the determination of the transmit power value is further based on the determined received pilot signal strength.

57. The non-transitory computer-readable medium of claim 56, wherein:

the determination of the received pilot signal strength comprises receiving pilot signals from a plurality of macro base stations, and determining which of the pilot signals has a highest received signal strength; and

the determined received pilot signal strength corresponds to the highest received signal strength.

58. The non-transitory computer-readable medium of claim 56, wherein the determination of the transmit power value further comprises:

determining a maximum amount of interference that a transmission from a first node may induce at a second node without causing a pilot-to-signal ratio for the node to fall below a minimum pilot-to-signal ratio, wherein the determination of the maximum amount of interference is based on the determined total received signal strength and the determined received pilot signal strength; and

determining the transmit power value such that the transmission does not induce a level of interference at the second node that exceeds the maximum amount of interference, wherein the determination of the transmit power value is further based on a path loss associated with a coverage area of the first node.

59. The non-transitory computer-readable medium of claim 58, wherein the determination of the transmit power value is further based on an adjacent channel interference rejection value between a first channel for which the transmit power value is determined and a second channel on which the total received signal strength is determined.

60. The non-transitory computer-readable medium of claim 56, wherein the computer-readable medium further comprises codes for causing the base station to determine at least one error associated with the determined total received signal strength and/or the determined received pilot signal strength, wherein the determination of the transmit power value is further based on the at least one error.

61. The non-transitory computer-readable medium of claim 55, wherein the computer-readable medium further comprises codes for causing the base station to:

determine whether a node is within a coverage area of an access node for which the transmit power value is determined; and

adjust the determined transmit power value based on the determination of whether the node is within the coverage area.

62. The non-transitory computer-readable medium of claim 55, wherein the transmit power value is determined to maintain a signal-to-noise ratio at a neighboring node to be less than or equal to a defined value.

63. The non-transitory computer-readable medium of claim 55, wherein:

the transmit power value is determined for a first node;

the non-transitory computer-readable medium further comprises codes for causing the base station to identify a second node that is substantially near an edge of a coverage area of the first node;

the non-transitory computer-readable medium further comprises codes for causing the base station to determine a signal-to-noise ratio associated with the second node based on the determined total received signal strength; and

the transmit power value is determined based on the determined signal-to-noise ratio and a defined maximum signal-to-noise ratio.

64. The non-transitory computer-readable medium of claim 55, wherein the transmit power value comprises a transmit power value for a common control channel.

65. The non-transitory computer-readable medium of claim 55, wherein the transmit power value comprises a maximum transmit power value.

66. The non-transitory computer-readable medium of claim 55, wherein the transmit power value is determined for a node that is restricted for least one of the group consisting of:

signaling, data access, registration, paging, and service to at least one node.

67. The non-transitory computer-readable medium of claim 55, wherein the transmit power value is determined for a femto node or a pico node.