INTERFERENCE MITIGATION FOR CONTROL CHANNELS IN A WIRELESS COMMUNICATION NETWORK

• US 20090197631A1
• Filed: 01/26/2009
• Published: 08/06/2009
• Est. Priority Date: 02/01/2008
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Bhushan, Naga, Palanki, Ravi, Agrawal, Avneesh, Khandekar, Aamod D.
• Granted Patent: US 8,504,091 B2
• Time in Patent Office: Days
• 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 to reduce interference on radio resources used for a control channel by a desired station;

sending the request to an interfering station; and

receiving the control channel on the radio resources from the desired station.

2. The method of claim 1, further comprising:

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

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

5. The method of claim 1, further comprising:

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

6. The method of claim 1, further comprising:

communicating with the desired station via the control channel for interference mitigation for data transmission.

7. The method of claim 1, wherein the request is sent by a user equipment (UE), wherein the interfering station is a macro base station having a first transmit power level, and wherein the desired station is a pico or femto base station having a second transmit power level lower than the first transmit power level.

8. The method of claim 1, wherein the request is sent by a user equipment (UE), wherein the interfering station is a femto base station with restricted access, and wherein the desired station is a pico or macro base station with unrestricted access.

9. The method of claim 1, wherein the request is sent by a base station, wherein the interfering station is a first user equipment (UE) not served by the base station, and wherein the desired station is a second UE served by the base station.

10. The method of claim 1, wherein the generating the request comprises generating the request to include at least one of a transmit power level of the request, a target interference level for the radio resources used for the control channel, an identity of the interfering station, an identity of the desired station, information identifying the control channel or the radio resources, a duration over which the request is valid, and priority of the request.

11. 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 station to detect for error in receiving the request.

12. 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 station.

13. The method of claim 12, 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 station.

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

15. The method of claim 1, wherein the request is sent by a user equipment (UE) during initial access, and wherein the control channel carries an access grant for the UE.

16. The method of claim 1, wherein the request is sent by a user equipment (UE) operating in an idle mode, and wherein the control channel comprises at least one of a paging channel and a broadcast channel carrying system information.

17. The method of claim 1, wherein the request is sent during handover of a user equipment (UE) or during operation in a connected mode by the UE.

18. The method of claim 1, further comprising:

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

19. An apparatus for wireless communication, comprising:

at least one processor configured to generate a request to reduce interference on radio resources used for a control channel by a desired station, to send the request to an interfering station, and to receive the control channel on the radio resources from the desired station.

20. The apparatus of claim 19, wherein the at least one processor is configured to detect high interference on the radio resources used for the control channel by the desired station, and to send the request in response to detecting high interference on the radio resources.

21. The apparatus of claim 19, wherein the at least one processor is configured to communicate with the desired station via the control channel for interference mitigation for data transmission.

22. An apparatus for wireless communication, comprising:

means for generating a request to reduce interference on radio resources used for a control channel by a desired station;

means for sending the request to an interfering station; and

means for receiving the control channel on the radio resources from the desired station.

23. The apparatus of claim 22, further comprising:

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

24. The apparatus of claim 22, further comprising:

means for communicating with the desired station via the control channel for interference mitigation for data transmission.

25. A computer program product, comprising:

a computer-readable medium comprising;

code for causing at least one computer to generate a request to reduce interference on radio resources used for a control channel by a desired station,

code for causing the at least one computer to send the request to an interfering station, and

code for causing the at least one computer to receive the control channel on the radio resources from the desired station.

26. A method for wireless communication, comprising:

receiving from a sender station a request to reduce interference on radio resources used for a control channel by a desired station; and

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

27. The method of claim 26, wherein the reducing transmit power comprises reducing transmit power of the interfering station on the radio resources to a lower level or zero.

28. The method of claim 26, wherein the reducing transmit power comprises

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

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

29. The method of claim 26, wherein the reducing transmit power comprises steering a transmission from the interfering station on the radio resources away from the sender station.

30. The method of claim 26, wherein the reducing transmit power comprises reducing the transmit power of the interfering station 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.

31. The method of claim 26, further comprising:

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

32. The method of claim 26, wherein the sender station is a user equipment (UE), the interfering station is a macro base station having a first transmit power level, and the desired station is a pico or femto base station having a second transmit power level lower than the first transmit power level.

33. The method of claim 26, wherein the sender station is a user equipment (UE), the interfering station is a femto base station with restricted access, and the desired station is a pico or macro base station with unrestricted access.

34. The method of claim 26, wherein the sender station is a base station, the interfering station is a first user equipment (UE) not served by the base station, and the desired station is a second UE served by the base station.

35. An apparatus for wireless communication, comprising:

at least one processor configured to receive from a sender station a request to reduce interference on radio resources used for a control channel by a desired station, and to reduce transmit power of an interfering station on the radio resources to reduce interference to the control channel from the desired station.

36. The apparatus of claim 35, wherein the at least one processor is configured to determine pathloss from the sender station to the interfering station based on a transmit power level and a received power level of the request, and to determine transmit power of the interfering station for the radio resources based on the pathloss and a target interference level for the radio resources.

37. The apparatus of claim 35, wherein the at least one processor is configured to reduce the transmit power of the interfering station 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.