REFERENCE SIGNAL RECEPTION AND CHANNEL STATE INFORMATION DETERMINATION FOR MULTIPLE NODES IN A WIRELESS COMMUNICATION NETWORK

• US 20120113816A1
• Filed: 11/03/2011
• Published: 05/10/2012
• Est. Priority Date: 11/05/2010
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Bhattad, Kapil, Chen, Wanshi, Gaal, Peter, Montojo, Juan
• Granted Patent: US 8,681,651 B2
• Time in Patent Office: Days
• US Class Current: 370/246
• CPC Class Codes: H04L 25/0226 sounding signals per se
• CPC Class Codes: H04L 5/0032 Distributed allocation, i.e. involving a plurality of allocating devices, each making partial allocation
• CPC Class Codes: H04W 72/27 between access points

Abstract

Techniques for receiving reference signals from multiple nodes and determining channel state information (CSI) for the nodes are disclosed. A user equipment (UE) may determine and report CSI for the multiple nodes to support data transmission to the UE. The nodes may transmit reference signals based on different configurations. The configuration for each node may indicate when, where, and how the node transmits its reference signal. The UE may determine CSI for different nodes and/or different combinations of nodes based on the reference signals transmitted by these nodes as well as an indication of which subframes to use to determine each CSI reported by the UE. The UE may report different CSIs for different subframes and may receive data transmission sent by a single node or a combination of nodes based on the reported CSIs.

Claims

1. A method for wireless communication, comprising:

receiving a first reference signal from a first node in first subframes by a user equipment (UE);

receiving a second reference signal from a second node in the first subframes and second subframes by the UE, the second reference signal coinciding with the first reference signal in the first subframes but not the second subframes;

receiving an indication to determine channel state information (CSI) separately for the first subframes and the second subframes;

determining first CSI for the first subframes by the UE based on the first and second reference signals received in the first subframes by the UE; and

determining second CSI for the second subframes by the UE based on the second reference signal received in the second subframes by the UE.

2. The method of claim 1, wherein the first node corresponds to a relay and the second node corresponds to a base station.

3. The method of claim 1, wherein the first and second nodes correspond to two cells supporting coordinated multi-point (CoMP) transmission to the UE.

4. The method of claim 1, wherein the receiving the first reference signal comprises receiving the first reference signal from the first node at a first periodicity, and wherein the receiving the second reference signal comprises receiving the second reference signal from the second node at a second periodicity different from the first periodicity.

5. The method of claim 4, wherein the first and second reference signals are both received at a third periodicity.

6. The method of claim 1, wherein the receiving the first reference signal comprises receiving the first reference signal from the first node at a first periodicity in third subframes, and wherein the receiving the second reference signal comprises receiving the second reference signal from the second node at the first periodicity in the second subframes, the second subframes being interlaced with the third subframes.

7. The method of claim 6, wherein the first subframes correspond to a subset of the third subframes to enable the UE to receive the first and second reference signals from both the first and second nodes in the first subframes.

8. The method of claim 1, wherein the first and second reference signals are received on same time-frequency resources in the first subframes.

9. The method of claim 1, wherein the first and second reference signals are received on different time-frequency resources in the first subframes.

10. The method of claim 1, wherein the first reference signal is received on first time-frequency resources, the second reference signal is received on second time-frequency resources, and both the first and second reference signals are received on third time-frequency resources in the first subframes.

11. The method of claim 1, wherein the receiving the first reference signal comprises receiving the first reference signal transmitted by the first node from a first set of antenna ports, and wherein the receiving the second reference signal comprises receiving the second reference signal transmitted by the second node from a second set of antenna ports different from the first set of antenna ports.

12. The method of claim 1, further comprising:

receiving the first reference signal from the first node in third subframes, the first reference signal not coinciding with the second reference signal in the third subframes; and

determining third CSI for the third subframes by the UE based on the first reference signal received in the third subframes by the UE.

13. The method of claim 1, wherein at least one of the first CSI or the second CSI comprises rank indicator (RI), channel quality indicator (CQI), precoding matrix indicator (PMI), channel direction indicator (CDI), or a combination thereof.

14. The method of claim 1, further comprising:

reporting the first CSI and the second CSI by the UE; and

receiving data transmission sent by only the first node, or only the second node, or both the first and second nodes based on the first CSI, or the second CSI, or both.

15. An apparatus for wireless communication, comprising:

at least one processor configured to receive a first reference signal from a first node in first subframes by a user equipment (UE), to receive a second reference signal from a second node in the first subframes and second subframes by the UE, the second reference signal coinciding with the first reference signal in the first subframes but not the second subframes, to receive an indication to determine channel state information (CSI) separately for the first subframes and the second subframes, to determine first CSI for the first subframes based on the first and second reference signals received in the first subframes, and to determine second CSI for the second subframes based on the second reference signal received in the second subframes.

16. The apparatus of claim 15, wherein the at least one processor is configured to receive the first reference signal from the first node at a first periodicity, and to receive the second reference signal from the second node at a second periodicity different from the first periodicity.

17. The apparatus of claim 15, wherein the at least one processor is configured to receive the first reference signal from the first node at a first periodicity in third subframes, and to receive the second reference signal from the second node at the first periodicity in the second subframes, the second subframes being interlaced with the third subframes.

18. The apparatus of claim 15, wherein the at least one processor is configured to receive the first reference signal transmitted by the first node from a first set of antenna ports, and to receive the second reference signal transmitted by the second node from a second set of antenna ports different from the first set of antenna ports.

19. The apparatus of claim 15, wherein the at least one processor is configured to receive the first reference signal from the first node in third subframes, the first reference signal not coinciding with the second reference signal in the third subframes, and to determine third CSI for the third subframes based on the first reference signal received in the third subframes.

20. An apparatus for wireless communication, comprising:

means for receiving a first reference signal from a first node in first subframes by a user equipment (UE);

means for receiving a second reference signal from a second node in the first subframes and second subframes by the UE, the second reference signal coinciding with the first reference signal in the first subframes but not the second subframes;

means for receiving an indication to determine channel state information (CSI) separately for the first subframes and the second subframes;

means for determining first CSI for the first subframes based on the first and second reference signals received in the first subframes; and

means for determining second CSI for the second subframes based on the second reference signal received in the second subframes.

21. The apparatus of claim 20, wherein the means for receiving the first reference signal comprises means for receiving the first reference signal from the first node at a first periodicity, and wherein the means for receiving the second reference signal comprises means for receiving the second reference signal from the second node at a second periodicity different from the first periodicity.

22. The apparatus of claim 20, wherein the means for receiving the first reference signal comprises means for receiving the first reference signal from the first node at a first periodicity in third subframes, and wherein the means for receiving the second reference signal comprises means for receiving the second reference signal from the second node at the first periodicity in the second subframes, the second subframes being interlaced with the third subframes.

23. The apparatus of claim 20, wherein the means for receiving the first reference signal comprises means for receiving the first reference signal transmitted by the first node from a first set of antenna ports, and wherein the means for receiving the second reference signal comprises means for receiving the second reference signal transmitted by the second node from a second set of antenna ports different from the first set of antenna ports.

24. The apparatus of claim 20, further comprising:

means for receiving the first reference signal from the first node in third subframes, the first reference signal not coinciding with the second reference signal in the third subframes; and

means for determining third CSI for the third subframes based on the first reference signal received in the third subframes.

25. A computer program product, comprising:

a non-transitory computer-readable medium comprising;

code for causing at least one processor to receive a first reference signal from a first node in first subframes by a user equipment (UE),

code for causing the at least one processor to receive a second reference signal from a second node in the first subframes and second subframes by the UE, the second reference signal coinciding with the first reference signal in the first subframes but not the second subframes,

code for causing the at least one processor to receive an indication to determine channel state information (CSI) separately for the first subframes and the second subframes,

code for causing the at least one processor to determine first CSI for the first subframes based on the first and second reference signals received in the first subframes, and

code for causing the at least one processor to determine second CSI for the second subframes based on the second reference signal received in the second subframes.

26. A method for wireless communication, comprising:

transmitting a first reference signal in first subframes by a first node, wherein a second reference signal is transmitted by a second node in the first subframes and second subframes, and wherein the first reference signal coincides with the second reference signal in the first subframes but not the second subframes; and

receiving first channel state information (CSI) for the first subframes from a user equipment (UE), the first CSI being determined by the UE based on the first and second reference signals received in the first subframes by the UE and based further on an indication for the UE to determine CSI separately for the first subframes and the second subframes.

27. The method of claim 26, further comprising:

transmitting the first reference signal in third subframes by the first node, the first reference signal not coinciding with the second reference signal in the third subframes; and

receiving second CSI for the third subframes from the UE, the second CSI being determined by the UE based on the first reference signal received in the third subframes by the UE and based further on an indication for the UE to determine CSI separately for the third subframes.

28. The method of claim 26, further comprising:

transmitting data from the first node to the UE based on the first CSI.

29. The method of claim 26, wherein the first reference signal is transmitted by the first node at a first periodicity, and wherein the second reference signal is transmitted by the second node at a second periodicity different from the first periodicity.

30. The method of claim 26, wherein the first reference signal is transmitted by the first node at a first periodicity in third subframes, and wherein the second reference signal is transmitted by the second node at the first periodicity in the second subframes, the second subframes being interlaced with the third subframes.

31. The method of claim 26, wherein the first node corresponds to a relay and the second node corresponds to a base station.

32. The method of claim 31, further comprising:

receiving a first transmission of data from the base station at the relay;

decoding the first transmission to recover the data sent by the base station; and

sending a second transmission of the data from the relay to the UE.

33. The method of claim 26, wherein the first and second nodes correspond to two cells for coordinated multi-point (CoMP) transmission to the UE.

34. The method of claim 33, further comprising:

performing precoding for a transmission of data based on the CSI; and

sending the transmission of data from the first node to the UE.

35. The method of claim 26, further comprising:

mapping first antenna ports of the first node to second antenna ports of the second node; and

transmitting the first reference signal from the first antenna ports of the first node to the UE.

36. The method of claim 26, further comprising:

transmitting the first reference signal from first antenna ports using a first set of resources in the first subframes by the first node, wherein the second reference signal is transmitted from second antenna ports using a second set of resources in the first subframes by the second node.

37. The method of claim 35, further comprising:

forming a plurality of virtual antennas based on a plurality of physical antennas at the first node, wherein the first antenna ports of the first node correspond to the plurality of virtual antennas.

38. An apparatus for wireless communication, comprising:

at least one processor configured to send a first reference signal in first subframes by a first node, wherein a second reference signal is transmitted by a second node in the first subframes and second subframes, and wherein the first reference signal coincides with the second reference signal in the first subframes but not the second subframes, and to receive first channel state information (CSI) for the first subframes from a user equipment (UE), the first CSI being determined by the UE based on the first and second reference signals received in the first subframes by the UE and based further on an indication for the UE to determine CSI separately for the first subframes and the second subframes.

39. The apparatus of claim 38, wherein the at least one processor is configured to transmit the first reference signal in third subframes by the first node, the first reference signal not coinciding with the second reference signal in the third subframes, and to receive second CSI for the third subframes from the UE, the second CSI being determined by the UE based on the first reference signal received in the third subframes by the UE and based further on an indication for the UE to determine CSI separately for the third subframes.

40. The apparatus of claim 38, wherein the first node corresponds to a relay and the second node corresponds to a base station, and wherein the at least one processor is configured to receive a first transmission of data from the base station at the relay, to decode the first transmission to recover the data sent by the base station, and to send a second transmission of the data from the relay to the UE.

41. The apparatus of claim 38, wherein the first and second nodes correspond to two cells for coordinated multi-point (CoMP) transmission to the UE, and wherein the at least one processor is configured to perform precoding for a transmission of data based on the CSI, and to send the transmission of data from the first node to the UE.

42. A method for wireless communication, comprising:

receiving a first transmission of data sent based on a first rank by a first node to a user equipment (UE); and

receiving a second transmission of the data sent based on a second rank by the first node, or a second node, or both the first and second nodes to the UE, the second rank being different from the first rank.

43. The method of claim 42, further comprising:

receiving a first reference signal from the first node;

determining the first rank based on the first reference signal;

receiving a second reference signal from the second node; and

determining the second rank based on the second reference signal.

44. The method of claim 42, further comprising:

concurrently receiving a first reference signal from the first node and a second reference signal from the second node; and

determining the second rank based on the first and second reference signals.

45. The method of claim 42, wherein the first node corresponds to a base station and the second node corresponds to a relay.

46. The method of claim 45, wherein the first rank is determined based on a backhaul channel between the base station and the relay or a direct channel between the base station and the UE.

47. The method of claim 46, wherein the second rank is determined based on an access channel between the relay and the UE or a composite channel comprising the access channel and the direct channel.

48. An apparatus for wireless communication, comprising:

at least one processor configured to receive a first transmission of data sent based on a first rank by a first node to a user equipment (UE), and to receive a second transmission of the data sent based on a second rank by the first node, or a second node, or both the first and second nodes to the UE, the second rank being different from the first rank.

49. The apparatus of claim 48, wherein the at least one processor is configured to receive a first reference signal from the first node, to determine the first rank based on the first reference signal, to receive a second reference signal from the second node, and to determine the second rank based on the second reference signal.

50. The apparatus of claim 48, wherein the at least one processor is configured to concurrently receive a first reference signal from the first node and a second reference signal from the second node, and to determine the second rank based on the first and second reference signals.

51. A method for wireless communication, comprising:

identifying a first transmission of data sent based on a first rank by a first node to a user equipment (UE); and

sending a second transmission of the data based on a second rank from the first node, or a second node, or both the first and second nodes to the UE, the second rank being different from the first rank.

52. The method of claim 51, further comprising:

receiving the first transmission of data at the second node;

decoding the first transmission to recover the data; and

generating the second transmission of the data based on the recovered data.

53. An apparatus for wireless communication, comprising:

at least one processor configured to identify a first transmission of data sent based on a first rank by a first node to a user equipment (UE), and to send a second transmission of the data based on a second rank from the first node, or a second node, or both the first and second nodes to the UE, the second rank being different from the first rank.

54. The apparatus of claim 53, wherein the at least one processor is configured to receive the first transmission of data at the second node, to decode the first transmission to recover the data, and to generate the second transmission of the data based on the recovered data.