POWER DECISION PILOT FOR A WIRELESS COMMUNICATION SYSTEM

• US 20090197629A1
• Filed: 10/30/2008
• Published: 08/06/2009
• Est. Priority Date: 02/01/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Horn, Gavin B., Sampath, Ashwin, Gorokhov, Alexei, Bhushan, Naga, Palanki, Ravi, Agrawal, Avneesh, Khandekar, Aamod, Borran, Mohammad J.
• Granted Patent: US 8,818,285 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04W 52/242 taking into account path loss
• CPC Class Codes: H04W 52/243 taking into account interferences
• CPC Class Codes: H04W 52/28 using user profile, e.g. mobile speed, priority or network state, e.g. standby, idle or non transmission
• CPC Class Codes: H04W 52/325 Power control of control or pilot channels
• 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
• CPC Class Codes: H04W 72/51 based on terminal or device properties

Abstract

Techniques for transmitting data with short-term interference mitigation in a wireless communication system are described. In one design, a first station (e.g., a base station or a terminal) may receive a message sent by a second station to request reduction of interference on at least one resource. In response to receiving the message, the first station may determine a first transmit power level to use for the at least one resource based on one or more factors such as a priority metric sent in the message, the buffer size at the first station, etc. The first station may send a power decision pilot on the at least one resource at a second transmit power level determined based on the first transmit power level.

Claims

1. A method for wireless communication, comprising:

receiving at a first station a message sent by a second station to request reduction of interference on at least one resource;

determining a first transmit power level to use for the at least one resource by the first station in response to receiving the message; and

sending a pilot from the first station at a second transmit power level determined based on the first transmit power level.

2. The method of claim 1, further comprising:

setting the second transmit power level equal to the first transmit power level.

3. The method of claim 1, further comprising:

setting the second transmit power level equal to a scaled version of the first transmit power level.

4. The method of claim 1, wherein the pilot is sent on the at least one resource in a first time period, and wherein the first transmit power level is used for the at least one resource in a second time period later than the first time period.

5. The method of claim 1, wherein the determining the first transmit power level comprises

estimating pathloss for the second station based on received power of the message, and

determining the first transmit power level based on a target interference level and the estimated pathloss for the second station.

6. The method of claim 1, wherein the determining the first transmit power level comprises determining the first transmit power level based on a buffer size at the first station.

7. The method of claim 1, further comprising:

obtaining priority information from the message; and

determining whether to grant or dismiss the message based on the priority information.

8. The method of claim 1, wherein the sending the pilot comprises

sending the pilot from multiple transmit antennas at the first station, the pilot being sent from each transmit antenna at a transmit power level selected for the transmit antenna.

9. The method of claim 8, further comprising:

determining transmit power levels for the multiple transmit antennas to steer power in a direction different from the second station.

10. The method of claim 1, further comprising:

determining precoding weights for multiple transmit antennas at the first station to reduce interference to the second station, and wherein the pilot is sent from the multiple transmit antennas in accordance with the precoding weights.

11. The method of claim 1, further comprising:

determining precoding weights for multiple transmit antennas at the first station to reduce interference to the second station; and

sending the precoding weights to the first second.

12. An apparatus for wireless communication, comprising:

at least one processor configured to receive at a first station a message sent by a second station to request reduction of interference on at least one resource, to determine a first transmit power level to use for the at least one resource by the first station in response to receiving the message, and to send a pilot from the first station at a second transmit power level determined based on the first transmit power level.

13. The apparatus of claim 12, wherein the at least one processor is configured to send the pilot on the at least one resource in a first time period, and to use the first transmit power level for the at least one resource in a second time period later than the first time period.

14. The apparatus of claim 12, wherein the at least one processor is configured to estimate pathloss for the second station based on received power of the message, and to determine the first transmit power level based on a target interference level and the estimated pathloss for the second station.

15. An apparatus for wireless communication, comprising:

means for receiving at a first station a message sent by a second station to request reduction of interference on at least one resource;

means for determining a first transmit power level to use for the at least one resource by the first station in response to receiving the message; and

means for sending a pilot from the first station at a second transmit power level determined based on the first transmit power level.

16. The apparatus of claim 15, wherein the pilot is sent on the at least one resource in a first time period, and wherein the first transmit power level is used for the at least one resource in a second time period later than the first time period.

17. The apparatus of claim 15, wherein the means for determining the first transmit power level comprises

means for estimating pathloss for the second station based on received power of the message, and

means for determining the first transmit power level based on a target interference level and the estimated pathloss for the second station.

18. A computer program product, comprising:

a computer-readable medium comprising;

code for causing at least one computer to receive at a first station a message sent by a second station to request reduction of interference on at least one resource,

code for causing at least one computer to determine a first transmit power level to use for the at least one resource by the first station in response to receiving the message, and

code for causing the at least one computer to send a pilot from the first station at a second transmit power level determined based on the first transmit power level.

19. A method for wireless communication, comprising:

receiving a message requesting transmit capability of a terminal for at least one resource; and

sending a pilot at a maximum transmit power level usable by the terminal for the at least one resource.

20. The method of claim 19, wherein the sending the pilot comprises

sending the pilot on the at least one resource in a first time period, and wherein the maximum transmit power level is usable for the at least one resource in a second time period later than the first time period.

21. The method of claim 19, further comprising:

receiving at least one message from at least one neighbor base station requesting reduction of interference on the at least one resource; and

determining the maximum transmit power level usable by the terminal for the at least one resource based on the at least one message.

22. The method of claim 21, wherein the determining the maximum transmit power level comprises

estimating pathloss for each of the at least one neighbor base station based on received power of a message received from the neighbor base station, and

determining the maximum transmit power level based on a target interference level and the estimated pathloss for each neighbor base station.

23. The method of claim 19, wherein the sending the pilot comprises

sending the pilot from multiple transmit antennas at the terminal, the pilot being sent from each transmit antenna at a transmit power level selected for the transmit antenna.

24. The method of claim 19, further comprising:

receiving a message from a neighbor base station requesting reduction of interference on the at least one resource;

determining preceding weights for multiple transmit antennas at the terminal to reduce interference to the neighbor base station; and

sending the pilot in accordance with the preceding weights.

25. An apparatus for wireless communication, comprising:

at least one processor configured to receive a message requesting transmit capability of a terminal for at least one resource, and to send a pilot at a maximum transmit power level usable by the terminal for the at least one resource.

26. The apparatus of claim 25, wherein the at least one processor is configured to send the pilot on the at least one resource in a first time period, and to use the maximum transmit power level for the at least one resource in a second time period later than the first time period.

27. The apparatus of claim 25, wherein the at least one processor is configured to receive the message from a serving base station, to receive at least one message from at least one neighbor base station requesting reduction of interference on the at least one resource, and to determine the maximum transmit power level usable by the terminal for the at least one resource based on the at least one message.

28. The apparatus of claim 27, wherein the at least one processor is configured to estimate pathloss for each of the at least one neighbor base station based on received power of a message received from the neighbor base station, and to determine the maximum transmit power level based on a target interference level and the estimated pathloss for each neighbor base station.

29. A method for wireless communication, comprising:

determining a first transmit power level to use for data transmission in a first time period;

determining a second transmit power level to use for pilot based on the first transmit power level; and

sending the pilot at the second transmit power level in a second time period earlier than the first time period.

30. The method of claim 29, wherein the determining the second transmit power level comprises setting the second transmit power level equal to the first transmit power level.

31. The method of claim 29, wherein the determining the second transmit power level comprises setting the second transmit power level equal to a scaled version of the first transmit power level.

32. The method of claim 29, further comprising:

receiving a message requesting reduction of interference on at least one resource in the first time interval, and wherein the pilot is sent on the at least one resource in the second time interval in response to receiving the message.

33. The method of claim 32, further comprising:

determining precoding weights for multiple transmit antennas to reduce interference to a transmitter of the message; and

sending the precoding weights to the transmitter of the message.

34. The method of claim 29, further comprising:

determining preceding weights for multiple transmit antennas to steer the pilot and the data transmission, and wherein the pilot is sent from the multiple transmit antennas in accordance with the preceding weights.

35. An apparatus for wireless communication, comprising:

at least one processor configured to determine a first transmit power level to use for data transmission in a first time period, to determine a second transmit power level to use for pilot based on the first transmit power level, and to send the pilot at the second transmit power level in a second time period earlier than the first time period.

36. The apparatus of claim 35, wherein the at least one processor is configured to set the second transmit power level equal to the first transmit power level.

37. The apparatus of claim 35, wherein the at least one processor is configured to receive a message requesting reduction of interference on at least one resource in the first time interval, and to send the pilot on the at least one resource in the second time interval in response to receiving the message.

38. A method for wireless communication, comprising:

estimating channel quality of at least one resource at a first station, the at least one resource having reduced interference from at least one interfering station; and

receiving a data transmission on the at least one resource from a second station.

39. The method of claim 38, further comprising:

sending information indicative of the estimated channel quality of the at least one resource to the second station.

40. The method of claim 38, further comprising:

selecting a modulation and coding scheme based on the estimated channel quality of the at least one resource; and

sending a resource grant comprising the selected modulation and coding scheme to the second station, wherein the data transmission is sent by the second station in accordance with the resource grant.

41. The method of claim 38, wherein the estimating the channel quality of the at least one resource comprises

receiving at least one pilot from the at least one interfering station, each pilot being sent at a transmit power level to be used on the at least one resource by a corresponding interfering station, and

estimating the channel quality of the at least one resource based on the at least one pilot from the at least one interfering station.

42. The method of claim 38, further comprising:

receiving a pilot from the second station, and wherein the channel quality of the at least one resource is estimated based on the pilot from the second station.

43. An apparatus for wireless communication, comprising:

at least one processor configured to estimate channel quality of at least one resource at a first station, the at least one resource having reduced interference from at least one interfering station, and to receive a data transmission on the at least one resource from a second station.

44. The apparatus of claim 43, wherein the at least one processor is configured to send information indicative of the estimated channel quality of the at least one resource to the second station.

45. The apparatus of claim 43, wherein the at least one processor is configured to select a modulation and coding scheme based on the estimated channel quality of the at least one resource, and to send a resource grant comprising the selected modulation and coding scheme to the second station, wherein the data transmission is sent by the second station in accordance with the resource grant.

46. The apparatus of claim 43, wherein the at least one processor is configured to receive at least one pilot from the at least one interfering station, each pilot being sent at a transmit power level to be used on the at least one resource by a corresponding interfering station, and to estimate the channel quality of the at least one resource based on the at least one pilot from the at least one interfering station.

47. The apparatus of claim 43, wherein the at least one processor is configured to receive a pilot from the second station and to estimate the channel quality of the at least one resource based on the pilot from the second station.