DYNAMIC SWITCHING BETWEEN COMMON REFERENCE SIGNAL INTERFERENCE CANCELATION AND RESOURCE ELEMENT PUNCTURING IN A CO-CHANNEL HETEROGENEOUS NETWORK

• US 20120087261A1
• Filed: 10/03/2011
• Published: 04/12/2012
• Est. Priority Date: 10/06/2010
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Yoo, Taesang, Luo, Tao, Mallik, Siddhartha, Damnjanovic, Aleksandar, Montojo, Juan
• Granted Patent: US 8,576,742 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04L 25/03 Shaping networks in transmitter or receiver, e.g. adaptive shaping networks

Abstract

Communication in a dominant interference scenario may be supported by performing inter-cell interference coordination (ICIC). Resource coordination/partitioning may be performed to allocate resources to a serving Node B located near the vicinity of a strong interfering Node B. The interfering Node B may avoid transmitting on the allocated/protected resources, possibly except for a common reference signal (CRS). A UE can then communicate with the serving Node B on the protected resources in the presence of the interfering Node B and may observe no interference (possibly except for the CRS) from the interfering Node B. When CRS tones of an interferer may collide with control/data tones of a serving cell, CRS interference cancellation (CRS IC) or puncturing of interfered resource elements (REs) may be appropriate. Certain aspects of the present disclosure provide techniques, where the UE may dynamically switch between CRS IC and RE puncturing based on certain parameters.

Claims

1. A method for wireless communications, comprising:

identifying subframes with interference between transmissions of a serving Node B and one or more non-serving Node Bs, wherein the subframes are identified based on cooperative partitioning of resources between the serving Node B and the one or more non-serving Node Bs;

measuring a parameter related to the interference; and

based on the measured parameter, determining whether to puncture resource elements (REs) of the subframes or to perform common reference signal interference cancellation (CRS IC) to reduce the interference.

2. The method of claim 1, wherein the parameter comprises at least one of a quality measure of CRS IC, a received signal strength for each of the non-serving Node Bs, a number indicating a quantity of REs that are subject to the interference, and a transport block size (TBS).

3. The method of claim 1, wherein determining whether to puncture the REs of the subframes or to perform the CRS IC is made per subframe, per RE of the subframe, per another time or frequency unit, or per non-serving Node B.

4. The method of claim 1, wherein the transmissions of the one or more non-serving Node Bs comprise CRS transmissions.

5. The method of claim 4, wherein performing CRS IC comprises subtracting at least one of the CRS transmissions of the one or more non-serving Node Bs from the transmissions of the serving Node B and the one or more non-serving Node Bs.

6. The method of claim 1, wherein identifying the subframes with the interference comprises:

measuring a received signal strength for each of the one or more non-serving Node Bs; and

determining whether the measured received signal strength for at least one of the non-serving Node Bs is greater than a threshold.

7. The method of claim 6, wherein measuring the received signal strength for each of the one or more non-serving Node Bs comprises receiving a strength metric from a neighbor cell search.

8. The method of claim 6, wherein measuring the received signal strength for each of the one or more non-serving Node Bs comprises estimating received CRS power from each of the one or more non-serving Node Bs.

9. The method of claim 1, wherein puncturing the REs of the subframes comprises zeroing out log-likelihood ratios (LLRs) generated from REs of the subframes that are subject to the interference.

10. The method of claim 1, wherein puncturing the REs of the subframes comprises multiplying log-likelihood ratios (LLRs) generated from REs of the subframes that are subject to the interference by a factor.

11. The method of claim 10, wherein the factor is greater than or equal to 0 and less than or equal to 1.

12. An apparatus for wireless communications, comprising:

means for identifying subframes with interference between transmissions of a serving Node B and one or more non-serving Node Bs, wherein the subframes are identified based on cooperative partitioning of resources between the serving Node B and the one or more non-serving Node Bs;

means for measuring a parameter related to the interference; and

based on the measured parameter, means for determining whether to puncture resource elements (REs) of the subframes or to perform common reference signal interference cancellation (CRS IC) to reduce the interference.

13. The apparatus of claim 12, wherein the parameter comprises at least one of a quality measure of CRS IC, a received signal strength for each of the non-serving Node Bs, a number indicating a quantity of REs that are subject to the interference, and a transport block size (TBS).

14. The apparatus of claim 12, wherein the means for determining whether to puncture the REs of the subframes or to perform the CRS IC is made per subframe, per RE of the subframe, per another time or frequency unit, or per non-serving Node B.

15. The apparatus of claim 12, wherein the transmissions of the one or more non-serving Node Bs comprise CRS transmissions.

16. The apparatus of claim 15, wherein means for performing CRS IC comprises means for subtracting at least one of the CRS transmissions of the one or more non-serving Node Bs from the transmissions of the serving Node B and the one or more non-serving Node Bs.

17. The apparatus of claim 12, wherein the means for identifying the subframes with the interference comprises:

means for measuring a received signal strength for each of the one or more non-serving Node Bs; and

means for determining whether the measured received signal strength for at least one of the non-serving Node Bs is greater than a threshold.

18. The apparatus of claim 17, wherein the means for measuring the received signal strength for each of the one or more non-serving Node Bs comprises means for receiving a strength metric from a neighbor cell search.

19. The apparatus of claim 17, wherein the means for measuring the received signal strength for each of the one or more non-serving Node Bs comprises means for estimating received CRS power from each of the one or more non-serving Node Bs.

20. The apparatus of claim 12, wherein means for puncturing the REs of the subframes comprises means for zeroing out log-likelihood ratios (LLRs) generated from REs of the subframes that are subject to the interference.

21. The apparatus of claim 12, wherein means for puncturing the REs of the subframes comprises means for multiplying log-likelihood ratios (LLRs) generated from REs of the subframes that are subject to the interference by a factor.

22. The apparatus of claim 21, wherein the factor is greater than or equal to 0 and less than or equal to 1.

23. An apparatus for wireless communications, comprising:

at least one processor configured to;

identify subframes with interference between transmissions of a serving Node B and one or more non-serving Node Bs, wherein the subframes are identified based on cooperative partitioning of resources between the serving Node B and the one or more non-serving Node Bs;

measure a parameter related to the interference; and

based on the measured parameter, determine whether to puncture resource elements (REs) of the subframes or to perform common reference signal interference cancellation (CRS IC) to reduce the interference; and

a memory coupled to the at least one processor.

24. The apparatus of claim 23, wherein the parameter comprises at least one of a quality measure of CRS IC, a received signal strength for each of the non-serving Node Bs, a number indicating a quantity of REs that are subject to the interference, and a transport block size (TBS).

25. The apparatus of claim 23, wherein the at least one processor configured to determine whether to puncture the REs of the subframes or to perform the CRS IC is made per subframe, per RE of the subframe, per another time or frequency unit, or per non-serving Node B.

26. The apparatus of claim 23, wherein the transmissions of the one or more non-serving Node Bs comprise CRS transmissions.

27. The apparatus of claim 26, wherein the at least one processor configured to perform CRS IC comprises subtracting at least one of the CRS transmissions of the one or more non-serving Node Bs from the transmissions of the serving Node B and the one or more non-serving Node Bs.

28. The apparatus of claim 23, wherein the at least one processor configured to identify the subframes with the interference comprises:

measuring a received signal strength for each of the one or more non-serving Node Bs; and

determining whether the measured received signal strength for at least one of the non-serving Node Bs is greater than a threshold.

29. The apparatus of claim 28, wherein the at least one processor configured to measure the received signal strength for each of the one or more non-serving Node Bs comprises receiving a strength metric from a neighbor cell search.

30. The apparatus of claim 28, wherein the at least one processor configured to measure the received signal strength for each of the one or more non-serving Node Bs comprises estimating received CRS power from each of the one or more non-serving Node Bs.

31. The apparatus of claim 23, wherein the at least one processor configured to puncture the REs of the subframes comprises zeroing out log-likelihood ratios (LLRs) generated from REs of the subframes that are subject to the interference.

32. The apparatus of claim 23, wherein the at least one processor configured to puncture the REs of the subframes comprises multiplying log-likelihood ratios (LLRs) generated from REs of the subframes that are subject to the interference by a factor.

33. The apparatus of claim 32, wherein the factor is greater than or equal to 0 and less than or equal to 1.

34. A computer-program product for wireless communications, the computer-program product comprising:

a computer-readable medium having code for;

identifying subframes with interference between transmissions of a serving Node B and one or more non-serving Node Bs, wherein the subframes are identified based on cooperative partitioning of resources between the serving Node B and the one or more non-serving Node Bs;

measuring a parameter related to the interference; and

based on the measured parameter, determining whether to puncture resource elements (REs) of the subframes or to perform common reference signal interference cancellation (CRS IC) to reduce the interference.

35. The computer-program product of claim 34, wherein the parameter comprises at least one of a quality measure of CRS IC, a received signal strength for each of the non-serving Node Bs, a number indicating a quantity of REs that are subject to the interference, and a transport block size (TBS).

36. The computer-program product of claim 34, wherein the code for determining whether to puncture the REs of the subframes or to perform the CRS IC is made per subframe, per RE of the subframe, per another time or frequency unit, or per non-serving Node B.

37. The computer-program product of claim 34, wherein the transmissions of the one or more non-serving Node Bs comprise CRS transmissions.

38. The computer-program product of claim 37, wherein the code for performing CRS IC comprises code for subtracting at least one of the CRS transmissions of the one or more non-serving Node Bs from the transmissions of the serving Node B and the one or more non-serving Node Bs.

39. The computer-program product of claim 34, wherein the code for identifying the subframes with the interference comprises code for:

measuring a received signal strength for each of the one or more non-serving Node Bs; and

determining whether the measured received signal strength for at least one of the non-serving Node Bs is greater than a threshold.

40. The computer-program product of claim 39, wherein the code for measuring the received signal strength for each of the one or more non-serving Node Bs comprises code for receiving a strength metric from a neighbor cell search.

41. The computer-program product of claim 39, wherein the code for measuring the received signal strength for each of the one or more non-serving Node Bs comprises code for estimating received CRS power from each of the one or more non-serving Node Bs.

42. The computer-program product of claim 34, wherein the code for puncturing the REs of the subframes comprises code for zeroing out log-likelihood ratios (LLRs) generated from REs of the subframes that are subject to the interference.

43. The computer-program product of claim 34, wherein the code for puncturing the REs of the subframes comprises code for multiplying log-likelihood ratios (LLRs) generated from REs of the subframes that are subject to the interference by a factor.

44. The computer-program product of claim 43, wherein the factor is greater than or equal to 0 and less than or equal to 1.