Adaptation of transmit power based on channel quality

• US 9,491,722 B2
• Filed: 08/06/2008
• Issued: 11/08/2016
• 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): Safaipour, Bobbak
• Application Number:
  US12/187,312
• Publication Number:
  US 20090042596A1
• Time in Patent Office: 3,016 Days
• Field of Search: 455/522, 370/318
• US Class Current: 1/1
• 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:

identifying that a visitor access terminal that is not authorized to handoff to a non-macro base station has entered into a non-macro coverage area for the non-macro base station;

determining a channel quality value associated with a channel used by the visitor access terminal; and

determining, by a transmit power controller in response to the identifying, a transmit power value including a reduced maximum transmission power level at which the non-macro base station is permitted to transmit to a home subscriber terminal that is based on the determined channel quality value and is configured to limit interference caused by the non-macro base station upon the visitor access terminal.

2. The method of claim 1, wherein the determination of the transmit power value comprises adjusting the transmit power value based on a change in the determined channel quality value or based on a comparison of the determined channel quality value with a threshold.

3. The method of claim 1, wherein the determination of the channel quality value comprises receiving an indication of channel quality from the home subscriber terminal.

4. The method of claim 1, further comprising:

identifying that the home subscriber terminal is located substantially near an edge of the non-macro coverage area for the non-macro base station,

wherein the determination of the transmit power value is further based upon an estimated distance between the non-macro base station and the edge of the non-macro coverage area,

wherein the determined channel quality value corresponds to a signal-to-noise ratio associated with the home subscriber terminal; and

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

5. The method of claim 4, wherein the determination of the signal-to-noise ratio comprises receiving signal-to-noise ratio information from the home subscriber terminal.

6. The method of claim 4, wherein the determination that the home subscriber terminal is located substantially near the edge of the coverage area for the non-macro base station is based on a path loss between the home subscriber terminal and the non-macro base station.

7. The method of claim 1, wherein the visitor subscriber terminal is restricted for least one of the group consisting of:

signaling, data access, registration, paging, and service to the non-macro base station.

8. The method of claim 1,

wherein the reduced maximum transmission power level is established for a common control channel, and

wherein the determined channel quality value indicates quality associated with the common control channel.

9. The method of claim 1, wherein the transmit power value comprises a downlink transmit power value for the non-macro base station.

10. The method of claim 1, wherein the reduced maximum transmission power level corresponds to a first preliminary maximum transmit power value, the method further comprising:

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

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

11. The method of claim 1, wherein the channel quality value and the transmit power value are determined on a repeated basis.

12. The method of claim 1, wherein the non-macro base station corresponds to a femto node or a pico node.

13. The method of claim 1,

wherein an estimated distance between the non-macro base station and the edge of the non-macro coverage area for the non-macro base station is used in conjunction with the determined channel quality value to calculate the reduced maximum transmission power level.

14. The method of claim 1,

wherein the channel quality value is a predefined path loss value indicative of path loss between the non-macro base station and an edge of the non-macro coverage area, or

wherein the channel quality value is based on an indication of path loss on the channel to a first home subscriber terminal of the non-macro base station, or

wherein the channel quality value is independently calculated at the non-macro base station based on a measurement report from a second home subscriber terminal.

15. An apparatus for wireless communication, comprising:

a node detector configured to identify that a visitor access terminal that is not authorized to handoff to a non-macro base station has entered into a non-macro coverage area for the non-macro base station;

a channel quality determiner configured to determine a channel quality value associated with a channel used by the visitor access terminal; and

a transmit power controller configured to determine, in response to the identification, a transmit power value including a reduced maximum transmission power level at which the non-macro base station is permitted to transmit to a home subscriber terminal that is based on the determined channel quality value and is configured to limit interference caused by the non-macro base station upon the visitor access terminal.

16. The apparatus of claim 15, wherein the determination of the transmit power value comprises adjusting the transmit power value based on a change in the determined channel quality value or based on a comparison of the determined channel quality value with a threshold.

17. The apparatus of claim 15, wherein the determination of the channel quality value comprises receiving an indication of channel quality from the home subscriber terminal.

18. The apparatus of claim 15,

wherein the node detector is further configured to identify that the home subscriber terminal is substantially near an edge of the non-macro coverage area of the non-macro base station;

a signal-to-noise ratio determiner configured to determine a signal-to-noise ratio associated with the home subscriber terminal based on the determined channel quality value,

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

wherein the transmit power value is determined further based upon an estimated distance between the non-macro base station and the edge of the non-macro coverage area.

19. The apparatus of claim 18, wherein the determination of the signal-to-noise ratio comprises receiving signal-to-noise ratio information from the home subscriber terminal.

20. The apparatus of claim 15, wherein the visitor subscriber terminal is restricted for least one of the group consisting of:

signaling, data access, registration, paging, and service to the non-macro base station.

21. The apparatus of claim 15,

wherein the reduced maximum transmission power level is established for a common control channel, and

wherein the determined channel quality value indicates quality associated with the common control channel.

22. The apparatus of claim 15, wherein the non-macro base station corresponds to a femto node or a pico node.

23. An apparatus for wireless communication, comprising:

means for identifying that a visitor access terminal that is not authorized to handoff to a non-macro base station has entered into a non-macro coverage area for the non-macro base station;

means for determining a channel quality value associated with a channel used by the visitor access terminal; and

means for determining, in response to the identification, a transmit power value including a reduced maximum transmission power level at which the non-macro base station is permitted to transmit to a home subscriber terminal that is based on the determined channel quality value and is configured to limit interference caused by the non-macro base station upon the visitor access terminal.

24. The apparatus of claim 23, wherein the determination of the transmit power value comprises adjusting the transmit power value based on a change in the determined channel quality value or based on a comparison of the determined channel quality value with a threshold.

25. The apparatus of claim 23, wherein the determination of the channel quality value comprises receiving an indication of channel quality from the home subscriber terminal.

26. The apparatus of claim 23,

wherein the means for identifying identifies that the home subscriber terminal that is substantially near an edge of the non-macro coverage area for the non-macro base station,

means for determining a signal-to-noise ratio associated with the home subscriber terminal based on the determined channel quality value,

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

wherein the transmit power value is determined further based upon an estimated distance between the non-macro base station and the edge of the non-macro coverage area.

27. The apparatus of claim 26, wherein the determination of the signal-to-noise ratio comprises receiving signal-to-noise ratio information from the home subscriber terminal.

28. The apparatus of claim 23, wherein the visitor subscriber terminal is restricted for least one of the group consisting of:

signaling, data access, registration, paging, and service to the non-macro base station.

29. The apparatus of claim 23,

wherein the reduced maximum transmission power level is established for a common control channel, and

wherein the determined channel quality value indicates quality associated with the common control channel.

30. The apparatus of claim 23, wherein the non-macro base station corresponds to a femto node or a pico node.

31. A non-transitory computer-readable medium containing instructions stored thereon, which, when executed by a computer, cause the computer to perform operations, the instructions comprising:

program code to identify that a visitor access terminal that is not authorized to handoff to a non-macro base station has entered into a non-macro coverage area for the non-macro base station;

program code to determine a channel quality value associated with a channel used by the visitor access terminal; and

program code to determine, in response to the identification, a transmit power value including a reduced maximum transmission power level at which the non-macro base station is permitted to transmit to a home subscriber terminal that is based on the determined channel quality value and is configured to limit interference caused by the non-macro base station upon the visitor access terminal.

32. The non-transitory computer-readable medium of claim 31, wherein the determination of the transmit power value comprises adjusting the transmit power value based on a change in the determined channel quality value or based on a comparison of the determined channel quality value with a threshold.

33. The non-transitory computer-readable medium of claim 31, wherein the determination of the channel quality value comprises receiving an indication of channel quality from the home subscriber terminal.

34. The non-transitory computer-readable medium of claim 31, further comprising:

program code to identify that the home subscriber terminal is located substantially near an edge of the non-macro coverage area for the non-macro base station,

program code to determine a signal-to-noise ratio associated with the home subscriber terminal based on the determined channel quality value,

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

wherein the transmit power value is determined further based upon an estimated distance between the non-macro base station and the edge of the non-macro coverage area.

35. The non-transitory computer-readable medium of claim 34, wherein the determination of the signal-to-noise ratio comprises receiving signal-to-noise ratio information from the home subscriber terminal.

36. The non-transitory computer-readable medium of claim 31, wherein the visitor subscriber terminal is restricted for least one of the group consisting of:

signaling, data access, registration, paging, and service to the non-macro base station.

37. The non-transitory computer-readable medium of claim 31,

wherein the reduced maximum transmission power level is established for a common control channel, and

wherein the determined channel quality value indicates quality associated with the common control channel.

38. The non-transitory computer-readable medium of claim 31, wherein the non-macro base station corresponds to a femto node or a pico node.