Interference mitigation for control channels in a wireless communication network

• US 8,504,091 B2
• Filed: 01/26/2009
• Issued: 08/06/2013
• Est. Priority Date: 02/01/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Palanki, Ravi, Khandekar, Aamod D., Bhushan, Naga, Agrawal, Avneesh
• Primary Examiner(s): NGUYEN, HAI V
• Application Number:
  US12/359,989
• Publication Number:
  US 20090197631A1
• Time in Patent Office: 1,653 Days
• Field of Search: 455/522
• US Class Current: 455/522
• 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 72/21 in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 72/541 using the level of interference
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Techniques for mitigating interference on control channels in a wireless communication network are described. In an aspect, high interference on radio resources used for a control channel may be mitigated by sending a request to reduce interference to one or more interfering stations. Each interfering station may reduce its transmit power on the radio resources, which may then allow the control channel to observe less interference. In one design, a user equipment (UE) may detect high interference on radio resources used for a control channel by a desired base station. The UE may send a request to reduce interference on the radio resources to an interfering base station, which may reduce its transmit power on the radio resources. The UE may receive the control channel on the radio resources from the desired base station and may observe less interference from the interfering base station.

Claims

1. A method for wireless communication, comprising:

generating a request by a user equipment (UE) to reduce interference on radio resources used for a control channel by a serving base station serving the UE;

sending the request to an interfering base station;

receiving, at the UE, the control channel on the radio resources from the serving base station; and

communicating with the serving base station via the control channel for interference mitigation for data transmission,

wherein the generating the request comprises generating the request to include one or more of a transmit power level of the request, an identity of the serving base station, a duration over which the request is valid, priority of the request, or a combination thereof.

2. The method of claim 1, further comprising:

detecting high interference on the radio resources used for the control channel by the serving base station, wherein the request is sent in response to detecting high interference on the radio resources.

3. The method of claim 1, further comprising:

identifying the interfering base station causing high interference on the radio resources used for the control channel by the serving base station, wherein the request is sent as a unicast message to the interfering base station.

4. The method of claim 1, wherein the request is sent as a broadcast message to the interfering base station and other interfering base stations within reception range of the request.

5. The method of claim 1, further comprising:

detecting the interfering base station based on a low reuse pilot (LRP) or a synchronization signal sent by the interfering base station.

6. The method of claim 1, wherein the interfering base station is a macro base station having a first transmit power level, and wherein the serving base station is a pico or femto base station having a second transmit power level lower than the first transmit power level.

7. The method of claim 1, wherein the interfering base station is a femto base station with restricted access, and wherein the serving base station is a pico or macro base station with unrestricted access.

8. The method of claim 1, wherein the generating the request further comprises generating the request to include one or more of a target interference level for the radio resources used for the control channel, an identity of the interfering base station, information identifying the control channel or the radio resources, or a combination thereof.

9. The method of claim 1, wherein the generating the request comprises

generating a cyclic redundancy check (CRC) for the request, and

appending the CRC to the request, the CRC being used by the interfering base station to detect for error in receiving the request.

10. The method of claim 1, wherein the sending the request comprises sending the request multiple times to improve reception of the request by the interfering base station.

11. The method of claim 10, wherein the sending the request multiple times comprises sending the request at higher transmit power after each time to further improve reception of the request by the interfering base station.

12. The method of claim 1, wherein the sending the request comprises sending the request via Layer 3 signaling.

13. The method of claim 1, wherein the control channel carries an access grant for the UE.

14. The method of claim 1, wherein the UE is operating in an idle mode, and wherein the control channel comprises one or more of a paging channel, a broadcast channel carrying system information, or a combination thereof.

15. The method of claim 1, wherein the request is sent during handover of the UE or during operation in a connected mode by the UE.

16. The method of claim 1, further comprising:

sending to the interfering base station a second request to extend interference reduction on the radio resources.

17. An apparatus for wireless communication, comprising:

at least one processor of a user equipment (UE) operatively connected to generate a request to reduce interference on radio resources used for a control channel by a serving base station serving the UE, to send the request to an interfering base station, to receive the control channel on the radio resources from the serving base station, and to communicate with the serving base station via the control channel for interference mitigation for data transmission,

wherein the generated request includes one or more of a transmit power level of the request, an identity of the serving base station, a duration over which the request is valid, priority of the request, or a combination thereof.

18. The apparatus of claim 17, wherein the at least one processor is operatively connected to detect high interference on the radio resources used for the control channel by the serving base station, and to send the request in response to detecting high interference on the radio resources.

19. An apparatus for wireless communication, comprising:

means, executable at a user equipment (UE), for generating a request to reduce interference on radio resources used for a control channel by a serving base station;

means, executable at the UE, for sending the request to an interfering, base station;

means, executable at the UE, for receiving the control channel on the radio resources from the serving base station; and

means, executable at the UE, for communicating with the serving base station via the control channel for interference mitigation for data transmission,

wherein the generated request includes one or more of a transmit power level of the request, an identity of the serving base station, a duration over which the request is valid, priority of the request, or a combination thereof.

20. The apparatus of claim 19, further comprising:

means for detecting high interference on the radio resources used for the control channel by the serving base station, wherein the request is sent in response to detecting high interference.

21. A computer program product, comprising:

a non-transitory computer-readable medium comprising;

code, executable at a user equipment (UE), for causing at least one computer to generate a request to reduce interference on radio resources used for a control channel by a serving base station,

code, executable at the UE, for causing the at least one computer to send the request to an interfering base station,

code, executable at the UE, for causing the at least one computer to receive the control channel on the radio resources from the serving base station; and

code, executable at the UE, for causing the at least one computer to communicate with the serving base station via the control channel for interference mitigation for data transmission,

wherein the generated request includes at least one of a transmit power level of the request, an identity of the serving base station, or priority of the request.

22. A method for wireless communication, comprising:

receiving, at an interfering user equipment (UE), a request from a base station to reduce interference on radio resources used for a control channel by the base station; and

reducing transmit power of the interfering UE on the radio resources to reduce interference to the control channel from the base station.

23. The method of claim 22, wherein the reducing transmit power comprises reducing transmit power of the interfering UE on the radio resources to a lower level or zero.

24. The method of claim 22, wherein the reducing transmit power comprises

determining pathloss from the base station to the interfering UE based on a received power level of the request, and

determining transmit power of the interfering UE for the radio resources based on the pathloss and a target interference level for the radio resources.

25. The method of claim 22, wherein the reducing transmit power comprises steering a transmission from the interfering UE on the radio resources away from the base station.

26. The method of claim 22, wherein the reducing transmit power comprises reducing the transmit power of the interfering UE on the radio resources for a predetermined duration, a duration indicated by the request, or a duration determined based on at least one parameter for the request.

27. The method of claim 22, further comprising:

determining the radio resources used for the control channel by the base station based on a hopping pattern and an identity of the base station.

28. The method of claim 22, wherein the interfering UE is a first UE not served by the base station.

29. An apparatus for wireless communication, comprising:

at least one processor at an interfering user equipment (UE) configured to receive from a base station a request to reduce interference on radio resources used for a control channel by the base station, and to reduce transmit power of the interfering UE on the radio resources to reduce interference to the control channel from the base station.

30. The apparatus of claim 29, wherein the at least one processor is configured to determine pathloss from the base station to the interfering UE based on a transmit power level and a received power level of the request, and to determine transmit power of the interfering UE for the radio resources based on the pathloss and a target interference level for the radio resources.

31. The apparatus of claim 29, wherein the at least one processor is configured to reduce the transmit power of the interfering UE on the radio resources for a predetermined duration, a duration indicated by the request, or a duration determined based on at least one parameter for the request.

32. A method for wireless communication, comprising:

transmitting, to one or more interfering user equipment (UEs), a request from a base station to reduce interference on radio resources used for a control channel by one or more UEs served by the base station; and

receiving on the radio resources of the control channel from the one or more served UEs, the radio resources having reduced interference from the one or more interfering UEs as a result of the interfering UEs reducing transmit power on the radio resources in response to the request.

33. The method of claim 32, wherein the interfering one or more UEs is a first one or more UEs not served by the base station.

34. An apparatus for wireless communication, comprising:

at least one processor at a base station configured to transmit a request to one or more interfering user equipment (UEs) to reduce interference on radio resources used for a control channel by one or more UEs served by the base station, and to receive on the radio resources of the control channel from the one or more served UEs, the radio resources having reduced interference from the one or more interfering UEs as a result of the interfering UEs reducing transmit power on the radio resources in response to the request.

35. An apparatus for wireless communication, comprising:

means, executable at the base station, for transmitting, to one or more interfering user equipment (UEs), a request from a base station to reduce interference on radio resources used for a control channel by one or more UEs served by the base station; and

means, executable at the base station, for receiving on the radio resources of the control channel from the one or more served UEs, the radio resources having reduced interference from the one or more interfering UEs as a result of the interfering UEs reducing transmit power on the radio resources in response to the request.

36. A computer program product, comprising:

a non-transitory computer-readable medium comprising;

code, executable at the base station, for transmitting, to one or more interfering user equipment (UEs), a request from a base station to reduce interference on radio resources used for a control channel by one or more UEs served by the base station; and

code, executable at the base station, for receiving on the radio resources of the control channel from the one or more served UEs, the radio resources having reduced interference from the one or more interfering UEs as a result of the interfering UEs reducing transmit power on the radio resources in response to the request.