Controlling access point transmit power based on access terminal ranking

• US 8,903,448 B2
• Filed: 02/18/2011
• Issued: 12/02/2014
• Est. Priority Date: 02/22/2010
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Chande, Vinay, Meshkati, Farhad, Patel, Chirag Sureshbhai, Yavuz, Mehmet, Nagaraja, Sumeeth
• Primary Examiner(s): SHARMA, SUJATHA R
• Application Number:
  US13/030,552
• Publication Number:
  US 20120046063A1
• Time in Patent Office: 1,383 Days
• Field of Search: 455/522, 455/69, 455/70, 455/450, 455/454, 455/455, 455/464, 455/517, 455/452.1, 455/127.1, 370/318, 370/328, 370335-338, 370/342, 370/329, 370/349, 370/441, 370/332
• US Class Current: 455/522
• CPC Class Codes: H04W 52/143 Downlink power control
• CPC Class Codes: H04W 52/16 Deriving transmission power values from another channel
• CPC Class Codes: H04W 52/18 TPC being performed according to specific parameters
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/34 TPC management, i.e. sharing limited amount of power among users or channels or data types, e.g. cell loading

Abstract

Transmit power for an access point is controlled based on measurement reports received by the access point from one or more access terminals that are not currently being served by the access point. In some aspects, transmit power is controlled based on the number of received messages that correspond to a particular event. In some aspects, transmit power is controlled based on the contents of the received messages. For example, the access point may use signal strength information included in the messages to determine a level of transmit power that mitigates interference at a defined subset of reporting access terminals.

Claims

1. A method of communication, comprising:

receiving messages at an access point, wherein the messages comprise measurement reports from a plurality of access terminals that are not currently being served by the access point;

ranking the access terminals based on the received messages, wherein the ranking corresponds to signal conditions at the access terminals that result from transmissions by the access point;

designating a subset of the access terminals based on the ranking, wherein designating the subset of access terminals comprises;

identifying a defined portion or defined number of the access terminals that reported a lowest received signal strength; and

excluding the identified access terminals from the subset of access terminals; and

controlling transmit power of the access point to achieve specified signal conditions at the subset of access terminals.

2. The method of claim 1, wherein:

the measurement reports include received signal strengths corresponding to signals the access terminals received from at least one other access point; and

the ranking is based on the received signal strengths.

3. The method of claim 1, wherein the controlling of the transmit power comprises adjusting the transmit power so that subsequently measured received signal strengths, corresponding to signals the subset of access terminals subsequently receive from the at least one other access point, will be greater than or equal to a defined threshold.

4. The method of claim 2, wherein the at least one other access point comprises at least one macro cell.

5. The method of claim 2, wherein the received signal strengths comprise common pilot channel (CPICH) Ec/Io or received signal code power (CPICH RSCP).

6. The method of claim 1, wherein:

the measurement reports include received signal strengths corresponding to signals the access terminals received from the access point; and

the ranking is based on the received signal strengths.

7. The method of claim 6, wherein the identification of the subset of access terminals comprises:

identifying a defined portion or defined number of the access terminals that reported highest received signal strength; and

excluding the identified access terminals from the subset of access terminals.

8. The method of claim 7, wherein the controlling of the transmit power comprises adjusting the transmit power so that subsequently measured received signal strengths, corresponding to signals the subset of access terminals subsequently receive from the access point, will be less than or equal to a defined threshold.

9. The method of claim 6, wherein the access point comprises a femto cell.

10. The method of claim 6, wherein the received signal strengths comprise CPICH Echo or CPICH RSCP.

11. The method of claim 1, wherein the messages comprise periodically received measurement report messages.

12. The method of claim 1, further comprising receiving other messages from at least one access terminal that is currently being served by the access point, wherein:

the other messages are indicative of channel quality on a forward link of the access point; and

the controlling of the transmit power is further based on the other messages.

13. The method of claim 1, further comprising:

determining that another access terminal near the access point is actively receiving information from another access point; and

restricting transmission by the access point as a result of the determination.

14. The method of claim 1, further comprising:

receiving pilot signals at the access point, wherein the pilot signals are received from at least one other access point;

identifying channel conditions at the access point based on the received pilot signals; and

setting at least one limit for the transmit power based on the identified channel conditions.

15. An apparatus for communication, comprising:

a receiver operable to receive messages, wherein the messages comprise measurement reports from a plurality of access terminals that are not currently being served by the apparatus; and

a controller operable to rank the access terminals based on the received messages, wherein the ranking corresponds to signal conditions at the access terminals that result from transmissions by the apparatus, and further operable to designate a subset of the access terminals based on the ranking, and further operable to control transmit power of the apparatus to achieve specified signal conditions at the subset of access terminals, wherein the designation of the subset of access terminals comprises identifying a defined portion or defined number of the access terminals that reported lowest received signal strength and excluding the identified access terminals from the subset of access terminals.

16. The apparatus of claim 15, wherein:

the measurement reports include received signal strengths corresponding to signals the access terminals received from at least one access point; and

the ranking is based on the received signal strengths.

17. The apparatus of claim 15, wherein the controlling of the transmit power comprises adjusting the transmit power so that subsequently measured received signal strengths, corresponding to signals the subset of access terminals subsequently receive from the at least one access point, will be greater than or equal to a defined threshold.

18. The apparatus of claim 16, wherein the at least one access point comprises at least one macro cell.

19. The apparatus of claim 16, wherein the received signal strengths comprise common pilot channel (CPICH) Ec/Io or received signal code power (CPICH RSCP).

20. The apparatus of claim 15, wherein:

the measurement reports include received signal strengths corresponding to signals the access terminals received from the apparatus; and

the ranking is based on the received signal strengths.

21. The apparatus of claim 20, wherein the identification of the subset of access terminals comprises:

identifying a defined portion or defined number of the access terminals that reported highest received signal strength; and

excluding the identified access terminals from the subset of access terminals.

22. The apparatus of claim 21, wherein the controlling of the transmit power comprises adjusting the transmit power so that subsequently measured received signal strengths, corresponding to signals the subset of access terminals subsequently receive from the apparatus, will be less than or equal to a defined threshold.

23. The apparatus of claim 20, wherein the apparatus comprises a femto cell.

24. The apparatus of claim 20, wherein the received signal strengths comprise CPICH Echo or CPICH RSCP.

25. The apparatus of claim 15, wherein the messages comprise periodically received measurement report messages.

26. The apparatus of claim 15, wherein:

the receiver is further operable to receive other messages from at least one access terminal that is currently being served by the apparatus;

the other messages are indicative of channel quality on a forward link of the apparatus; and

the controlling of the transmit power is further based on the other messages.

27. The apparatus of claim 15, wherein the controller is further operable to:

determine that another access terminal near the apparatus is actively receiving information from an access point; and

restrict transmission by the apparatus as a result of the determination.

28. The apparatus of claim 15, wherein:

the receiver is further operable to receive pilot signals from at least one access point;

the controller is further operable to identify channel conditions at the apparatus based on the received pilot signals; and

the controller is further operable to set at least one limit for the transmit power based on the identified channel conditions.

29. An apparatus for communication, comprising:

means for receiving messages, wherein the messages comprise measurement reports from a plurality of access terminals that are not currently being served by the apparatus;

means for ranking the access terminals based on the received messages, wherein the ranking corresponds to signal conditions at the access terminals that result from transmissions by the apparatus;

means for designating a subset of the access terminals based on the ranking, wherein the means for designating of the subset of access terminals comprises;

means for identifying a defined portion or defined number of the access terminals that reported lowest received signal strength; and

means for excluding the identified access terminals from the subset of access terminals; and

means for controlling transmit power of the apparatus to achieve specified signal conditions at the subset of access terminals.

30. The apparatus of claim 29, wherein:

the measurement reports include received signal strengths corresponding to signals the access terminals received from at least one access point; and

the ranking is based on the received signal strengths.

31. The apparatus of claim 29, wherein the controlling of the transmit power comprises adjusting the transmit power so that subsequently measured received signal strengths, corresponding to signals the subset of access terminals subsequently receive from the at least one access point, will be greater than or equal to a defined threshold.

32. The apparatus of claim 29, wherein:

the measurement reports include received signal strengths corresponding to signals the access terminals received from the apparatus; and

the ranking is based on the received signal strengths.

33. The apparatus of claim 32, wherein the identification of the subset of access terminals comprises:

identifying a defined portion or defined number of the access terminals that reported highest received signal strength; and

excluding the identified access terminals from the subset of access terminals.

34. The apparatus of claim 33, wherein the controlling of the transmit power comprises adjusting the transmit power so that subsequently measured received signal strengths, corresponding to signals the subset of access terminals subsequently receive from the apparatus, will be less than or equal to a defined threshold.

35. The apparatus of claim 29, further comprising:

means for determining that another access terminal near the apparatus is actively receiving information from an access point; and

means for restricting transmission by the apparatus as a result of the determination.

36. The apparatus of claim 29, further comprising:

means for receiving pilot signals from at least one access point;

means for identifying channel conditions at the apparatus based on the received pilot signals; and

means for setting at least one limit for the transmit power based on the identified channel conditions.

37. A computer-program product, comprising:

a non-transitory computer-readable medium comprising code for causing a computer to;

receive messages at an access point, wherein the messages comprise measurement reports from a plurality of access terminals that are not currently being served by the access point;

rank the access terminals based on the received messages, wherein the ranking corresponds to signal conditions at the access terminals that result from transmissions by the access point;

designate a subset of the access terminals based on the ranking, wherein the designation of the subset of access terminals comprises;

identifying a defined portion or defined number of the access terminals that reported lowest received signal strength; and

excluding the identified access terminals from the subset of access terminals; and

control transmit power of the access point to achieve specified signal conditions at the subset of access terminals.

38. The computer-program product of claim 37, wherein:

the measurement reports include received signal strengths corresponding to signals the access terminals received from at least one other access point; and

the ranking is based on the received signal strengths.

39. The computer-program product of claim 37, wherein the controlling of the transmit power comprises adjusting the transmit power so that subsequently measured received signal strengths, corresponding to signals the subset of access terminals subsequently receive from the at least one other access point, will be greater than or equal to a defined threshold.

40. The computer-program product of claim 37, wherein:

the measurement reports include received signal strengths corresponding to signals the access terminals received from the access point; and

the ranking is based on the received signal strengths.

41. The computer-program product of claim 40, wherein the identification of the subset of access terminals comprises:

identifying a defined portion or defined number of the access terminals that reported highest received signal strength; and

excluding the identified access terminals from the subset of access terminals.

42. The computer-program product of claim 41, wherein the controlling of the transmit power comprises adjusting the transmit power so that subsequently measured received signal strengths, corresponding to signals the subset of access terminals subsequently receive from the access point, will be less than or equal to a defined threshold.

43. The computer-program product of claim 37, wherein the computer-readable medium further comprises code for causing the computer to:

determine that another access terminal near the access point is actively receiving information from another access point; and

restrict transmission by the access point as a result of the determination.

44. The computer-program product of claim 37, wherein the computer-readable medium further comprises code for causing the computer to:

receive pilot signals at the access point, wherein the pilot signals are received from at least one other access point;

identify channel conditions at the access point based on the received pilot signals; and

set at least one limit for the transmit power based on the identified channel conditions.