INTERFERENCE MANAGEMENT WITH REDUCE INTERFERENCE REQUESTS AND INTERFERENCE INDICATORS

• US 20100099449A1
• Filed: 04/16/2009
• Published: 04/22/2010
• Est. Priority Date: 04/22/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Bhushan, Naga, Agrawal, Avneesh, Ji, Tingfang, Khandekar, Aamod D., Borran, Mohammad J., Gorokhov, Alexei Y.
• Granted Patent: US 8,521,206 B2
• Time in Patent Office: Days
• US Class Current: 455/501
• CPC Class Codes: H04W 52/243 taking into account interferences
• CPC Class Codes: H04W 72/54 based on quality criteria

Abstract

Techniques for managing interference in a wireless network are described. In an aspect, reduce interference requests and interference indicators may be used for interference management to enable operation in scenarios with dominant interferers. In one design, a terminal may receive a reduce interference request from a first base station requesting lower interference on specified time-frequency resources. The terminal may also receive an interference indicator conveying the interference observed by a second base station. The terminal may determine its transmit power based on the reduce interference request and the interference indicator. For example, the terminal may determine an initial transmit power based on the reduce interference request (or the interference indicator) and may adjust the initial transmit power based on the interference indicator (or the reduce interference request) to obtain its transmit power. The terminal may transmit data to a serving base station at the determined transmit power.

Claims

1. A method for wireless communication, comprising:

receiving a reduce interference request from a first base station requesting lower interference on specified time-frequency resources;

receiving an interference indicator conveying interference observed by a second base station; and

determining transmit power of a terminal based on the reduce interference request and the interference indicator.

2. The method of claim 1, wherein the determining the transmit power of the terminal comprises

determining whether to honor or dismiss the reduce interference request based on at least one of decoding result for the reduce interference request, a priority level of the reduce interference request, a priority level of the terminal, pathloss from the first base station to the terminal, pathloss from a serving base station to the terminal, received power or received signal quality of the first base station, a resource assignment size for the terminal, and the transmit power of the terminal, and

determining the transmit power of the terminal based on the reduce interference request if a determination is made to honor the reduce interference request.

3. The method of claim 1, wherein the determining the transmit power of the terminal comprises

determining whether to honor or dismiss the interference indicator based on at least one of decoding result for the interference indicator, pathloss from the second base station to the terminal, pathloss from a serving base station to the terminal, received power or received signal quality of the second base station, power classes of the serving base station and the second base station, and association types of the serving base station and the second base station, and

determining the transmit power of the terminal based on the interference indicator if a determination is made to honor the interference indicator.

4. The method of claim 1, further comprising:

dismissing the interference indicator if received from a base station of a first power class and if the terminal is served by a base station of a second power class; and

honoring the interference indicator with greater weight or higher priority if received from a base station of the second power class and if the terminal is served by a base station of the first power class.

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

determining an initial transmit power based on the reduce interference request, and

adjusting the initial transmit power based on the interference indicator to obtain the transmit power of the terminal.

6. The method of claim 1, wherein the determining the transmit power of the terminal comprises

determining an initial transmit power based on the interference indicator, and

adjusting the initial transmit power based on the reduce interference request to obtain the transmit power of the terminal.

7. The method of claim 1, wherein the determining the transmit power of the terminal comprises

determining a target interference level for the specified time-frequency resources at the first base station based on the reduce interference request,

determining pathloss from the first base station to the terminal, and

determining the transmit power of the terminal based on the target interference level and the pathloss.

8. The method of claim 7, wherein the determining the transmit power of the terminal further comprises

determining a back-off factor based on the interference indicator, and

determining the transmit power of the terminal based further on the back-off factor.

9. The method of claim 1, wherein the determining the transmit power of the terminal comprises adjusting transmit power of the terminal for a prior time interval based on the interference indicator to obtain transmit power of the terminal for a current time interval.

10. The method of claim 1, wherein the determining the transmit power of the terminal comprises

adjusting a power offset for a prior time interval based on the interference indicator to obtain a power offset for a current time interval, and

determining the transmit power of the terminal based on the power offset for the current time interval and a reference power level.

11. The method of claim 1, wherein the determining the transmit power of the terminal comprises

determining at least one of a maximum transmit power level and a minimum transmit power level based on at least one of the reduce interference request and the interference indicator,

determining an initial transmit power based on the interference indicator or the reduce interference request, and

limiting the initial transmit power based on at least one of the maximum and minimum transmit power levels to obtain the transmit power of the terminal.

12. The method of claim 1, wherein the interference indicator conveys at least one of interference observed by the second base station, whether the second base station is overloaded, and advance notice of high interference due to terminals served by the second base station.

13. The method of claim 1, further comprising:

transmitting data to a serving base station at the determined transmit power; and

determining whether or not to transmit on designated resources for the second base station based on a decision to honor or dismiss the interference indicator, the designated resources being used by the second base station to determine controlled interference or uncontrolled interference at the second base station.

14. The method of claim 1, wherein the first and second base stations are same base station.

15. An apparatus for wireless communication, comprising:

means for receiving a reduce interference request from a first base station requesting lower interference on specified time-frequency resources;

means for receiving an interference indicator conveying interference observed by a second base station; and

means for determining transmit power of a terminal based on the reduce interference request and the interference indicator.

16. The apparatus of claim 15, wherein the means for determining the transmit power of the terminal comprises

means for determining whether to honor or dismiss the reduce interference request,

means for determining whether to honor or dismiss the interference indicator, and

means for determining the transmit power of the terminal based on the reduce interference request if a determination is made to honor the reduce interference request and based on the interference indicator if a determination is made to honor the interference indicator.

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

means for determining an initial transmit power based on the reduce interference request, and

means for adjusting the initial transmit power based on the interference indicator to obtain the transmit power of the terminal.

18. The apparatus of claim 15, wherein the means for determining the transmit power of the terminal comprises

means for determining an initial transmit power based on the interference indicator, and

means for adjusting the initial transmit power based on the reduce interference request to obtain the transmit power of the terminal.

19. The apparatus of claim 15, further comprising:

means for transmitting data to a serving base station at the determined transmit power; and

means for determining whether or not to transmit on designated resources for the second base station based on a decision to honor or dismiss the interference indicator, the designated resources being used by the second base station to determine controlled interference or uncontrolled interference at the second base station.

20. An apparatus for wireless communication, comprising:

at least one processor configured to receive a reduce interference request from a first base station requesting lower interference on specified time-frequency resources, to receive an interference indicator conveying interference observed by a second base station, and to determine transmit power of a terminal based on the reduce interference request and the interference indicator.

21. The apparatus of claim 20, wherein the at least one processor is configured to determine whether to honor or dismiss the reduce interference request, to determine whether to honor or dismiss the interference indicator, and to determine the transmit power of the terminal based on the reduce interference request if a determination is made to honor the reduce interference request and based on the interference indicator if a determination is made to honor the interference indicator.

22. The apparatus of claim 20, wherein the at least one processor is configured to determine an initial transmit power based on the reduce interference request, and to adjust the initial transmit power based on the interference indicator to obtain the transmit power of the terminal.

23. The apparatus of claim 20, wherein the at least one processor is configured to determine an initial transmit power based on the interference indicator, and to adjust the initial transmit power based on the reduce interference request to obtain the transmit power of the terminal.

24. The apparatus of claim 20, wherein the at least one processor is configured to send data to a serving base station at the determined transmit power, and to determine whether or not to transmit on designated resources for the second base station based on a decision to honor or dismiss the interference indicator, the designated resources being used by the second base station to determine controlled interference or uncontrolled interference at the second base station.

25. A computer program product, comprising:

a computer-readable medium comprising;

code for causing at least one computer to receive a reduce interference request from a first base station requesting lower interference on specified time-frequency resources,

code for causing the at least one computer to receive an interference indicator conveying interference observed by a second base station, and

code for causing the at least one computer to determine transmit power of a terminal based on the reduce interference request and the interference indicator.

26. A method for wireless communication, comprising:

receiving at a serving base station a reduce interference request sent by a first base station to request lower interference on specified time-frequency resources;

receiving at the serving base station an interference indicator conveying interference observed by a second base station; and

scheduling a terminal for data transmission on the specified time-frequency resources based on the reduce interference request and the interference indicator.

27. The method of claim 26, further comprising:

determining whether to honor or dismiss the reduce interference request based on at least one of a priority level of the reduce interference request, pathloss from the first base station to the terminal, pathloss from the serving base station to the terminal, a resource assignment size for the terminal, transmit power of the terminal, and received signal quality of the terminal at the serving base station, and wherein the terminal is scheduled based on the reduce interference request if a determination is made to honor the reduce interference request.

28. The method of claim 26, further comprising:

determining whether to honor or dismiss the interference indicator based on at least one of pathloss from the second base station to the terminal, pathloss from the serving base station to the terminal, power classes of the serving base station and the second base station, and association types of the serving base station and the second base station, and wherein the terminal is scheduled based on the interference indicator if a determination is made to honor the interference indicator.

29. The method of claim 26, further comprising:

sending to the first base station a response message comprising a projected interference level due to the terminal being scheduled on the specified time-frequency resources.

30. The method of claim 26, wherein the scheduling the terminal comprises

determining an initial transmit power based on at least one of the reduce interference request, at least one variable maintained by the serving base station for the terminal, and information reported by the terminal to the serving base station, and

adjusting the initial transmit power based on the interference indicator to obtain transmit power of the terminal.

31. The method of claim 26, wherein the scheduling the terminal comprises

determining an initial transmit power based on at least one of the interference indicator, at least one variable maintained by the serving base station for the terminal, and information reported by the terminal to the serving base station, and

adjusting the initial transmit power based on the reduce interference request to obtain transmit power of the terminal.

32. An apparatus for wireless communication, comprising:

means for receiving at a serving base station a reduce interference request sent by a first base station to request lower interference on specified time-frequency resources;

means for receiving at the serving base station an interference indicator conveying interference observed by a second base station; and

means for scheduling a terminal for data transmission on the specified time-frequency resources based on the reduce interference request and the interference indicator.

33. The apparatus of claim 32, wherein the means for scheduling the terminal comprises

means for determining whether to honor or dismiss the reduce interference request,

means for determining whether to honor or dismiss the interference indicator, and

means for scheduling the terminal based on the reduce interference request if a determination is made to honor the reduce interference request and based on the interference indicator if a determination is made to honor the interference indicator.

34. The apparatus of claim 32, further comprising:

means for sending to the first base station a response message comprising a projected interference level due to the terminal being scheduled on the specified time-frequency resources.

35. The apparatus of claim 32, wherein the means for scheduling the terminal comprises

means for determining an initial transmit power based on at least one of the reduce interference request and the interference indicator, and

means for adjusting the initial transmit power based on at least one of the interference indicator and the interference indicator to obtain transmit power of the terminal.

36. A method for wireless communication, comprising:

sending a reduce interference request to request lower interference on specified time-frequency resources at a base station; and

sending an interference indicator conveying interference observed by the base station.

37. The method of claim 36, wherein the sending the reduce interference request comprises sending the reduce interference request over the air to at least one interfering terminal in at least one neighbor cell, each interfering terminal adjusting its transmit power based on the reduce interference request.

38. The method of claim 36, wherein the sending the reduce interference request comprises sending the reduce interference request via a backhaul to at least one neighbor base station, each neighbor base station scheduling terminals based on the reduce interference request.

39. The method of claim 36, wherein the sending the interference indicator comprises sending the interference indicator over the air to terminals in neighbor cells, each terminal adjusting its transmit power based on the interference indicator.

40. The method of claim 36, wherein the sending the interference indicator comprises sending the interference indicator via a backhaul to at least one neighbor base station, each neighbor base station controlling transmit power of terminals served by the neighbor base station based on the interference indicator.

41. The method of claim 36, wherein the sending the reduce interference request comprises

determining transmit power of the reduce interference request based on a target interference level for the specified time-frequency resources at the base station, and

sending the reduce interference request at the determined transmit power.

42. The method of claim 36, wherein the reduce interference request conveys at least one of the specified time-frequency resources, a priority level of a terminal or data to be scheduled on the specified resources, a target interference level for the specified resources at the base station, and a projected interference level on the specified resources due to the terminal to be scheduled on the specified resources.

43. The method of claim 36, further comprising:

determining whether or not to send the interference indicator based on uncontrolled interference at the base station.

44. The method of claim 43, further comprising:

measuring received power of designated resources used by the base station to determine the uncontrolled interference or controlled interference at the base station; and

estimating the uncontrolled interference at the base station based on the received power of the designated resources.

45. The method of claim 43, further comprising:

receiving reduce interference requests from neighbor base stations;

determining, based on the reduce interference requests, projected interference levels at the base station due to terminals in neighbor cells; and

estimating the uncontrolled interference at the base station based on the projected interference levels.

46. An apparatus for wireless communication, comprising:

means for sending a reduce interference request to request lower interference on specified time-frequency resources at a base station; and

means for sending an interference indicator conveying interference observed by the base station.

47. The apparatus of claim 46, wherein the means for sending the interference indicator comprises

means for determining transmit power of the reduce interference request based on a target interference level for the specified time-frequency resources at the base station, and

means for sending the reduce interference request at the determined transmit power.

48. The apparatus of claim 46, further comprising:

means for measuring received power of designated resources used by the base station to determine uncontrolled interference or controlled interference at the base station;

means for estimating the uncontrolled interference at the base station based on the received power of the designated resources; and

means for determining whether or not to send the interference indicator based on the uncontrolled interference at the base station.