Method and apparatus for channel feedback based on reference signal

• US 9,107,104 B2
• Filed: 12/02/2013
• Issued: 08/11/2015
• Est. Priority Date: 01/14/2010
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Chen, Wanshi, Bhattad, Kapil, Gaal, Peter, Gorokhov, Alexei Yurievitch, Montojo, Juan
• Primary Examiner(s): Ho, Chuong T
• Application Number:
  US14/094,548
• Publication Number:
  US 20140086092A1
• Time in Patent Office: 617 Days
• Field of Search: 370/252, 370/253, 370/254, 370328-329
• US Class Current: 1/1
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/0028 Formatting
• CPC Class Codes: H04L 5/0041 Frequency-non-contiguous
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic

Abstract

Techniques for supporting channel measurement and reporting in a wireless communication system are described. In one design, a cell transmits a cell-specific reference signal (CRS) used for channel estimation and coherent demodulation and a channel spatial information reference signal (CSI-RS) used for channel measurement and channel feedback reporting. The cell may transmit the CSI-RS less frequently than the CRS, or from more antenna ports than the CRS, or on fewer resource elements than the CRS, or a combination thereof. In one design, a user equipment (UE) determines at least one bandwidth part configured for the UE, with each bandwidth part covering at least one subband. The UE receives the CRS and CSI-RS from the cell, determines channel feedback information for the at least one bandwidth part based on the CSI-RS, sends the channel feedback information to the cell, and receives data transmitted by the cell based on the channel feedback information.

Claims

1. A method for wireless communication, comprising:

determining at least one bandwidth part configured for a user equipment (UE), each bandwidth part covering at least one subband among a plurality of subbands, each bandwidth part comprising less than all of a system bandwidth;

receiving a first reference signal and a second reference signal, the second reference signal being transmitted less frequently than the first reference signal; and

determining channel feedback information for the at least one bandwidth part based on the second reference signal, wherein the second reference signal comprises a channel state information reference signal.

2. The method of claim 1, wherein the first reference signal comprises a cell-specific reference signal (CRS).

3. The method of claim 1, wherein determining the channel feedback information comprises determining channel feedback information for all bandwidth parts configured for the UE.

4. The method of claim 1, wherein determining the channel feedback information comprises determining channel feedback information for each bandwidth part configured for the UE.

5. The method of claim 1, wherein determining the channel feedback information comprises determining channel feedback information for each subband in each bandwidth part configured for the UE.

6. The method of claim 1, wherein receiving the second reference signal comprises receiving the second reference signal transmitted across a system bandwidth;

wherein determining the channel feedback information comprises determining the channel feedback information based on the second reference signal for only a portion of the system bandwidth corresponding to the at least one bandwidth part.

7. The method of claim 1, further comprising obtaining a set of one or more bandwidth parts applicable for the UE, wherein the at least one bandwidth part configured for the UE includes the one or more bandwidth parts in the set.

8. The method of claim 1, wherein the channel feedback information comprises one or more of channel quality indicator (CQI), or rank indicator (RI), or precoding matrix indicator (PMI), or channel direction indicator (CDI), or a combination thereof.

9. An apparatus for wireless communication, comprising:

means for determining at least one bandwidth part configured for a user equipment (UE), each bandwidth part covering at least one subband among a plurality of subbands, each bandwidth part comprising less than an entire system bandwidth;

means for receiving a first reference signal and a second reference signal, the second reference signal being transmitted less frequently than the first reference signal; and

means for determining channel feedback information for the at least one bandwidth part based on the second reference signal, wherein the second reference signal comprises a channel state information reference signal.

10. The apparatus of claim 9, wherein the means for determining channel feedback information comprises means for determining channel feedback information for all bandwidth parts configured for the UE, or for each bandwidth part configured for the UE, or for each subband in each bandwidth part configured for the UE.

11. The apparatus of claim 9, further comprising means for obtaining a set of bandwidth parts, wherein the at least one bandwidth part configured for the UE is included in the set of bandwidth parts.

12. The apparatus of claim 9, further comprising:

means for sending the channel feedback information for the at least one bandwidth part; and

means for receiving data transmitted to the UE based on the channel feedback information.

13. An apparatus for wireless communication, comprising:

a memory unit; and

at least one processor coupled to the memory unit, wherein the at least on processor is configured;

to determine at least one bandwidth part configured for a user equipment (UE), each bandwidth part covering at least one subband among a plurality of subbands, each bandwidth part comprising less than an entire system bandwidth,

to receive a first reference signal and a second reference signal, the second reference signal being transmitted less frequently than the first reference signal, and

to determine channel feedback information for the at least one bandwidth part based on the second reference signal, wherein the second reference signal comprises a channel state information reference signal.

14. A computer program product for wireless communications, the computer program product comprising a non-transitory computer-readable medium having program code recorded thereon, the program code comprising:

program code for causing at least one processor to determine at least one bandwidth part configured for a user equipment (UE), each bandwidth part covering at least one subband among a plurality of subbands, each bandwidth part comprising less than an entire system bandwidth;

program code for causing the at least one processor to receive a first reference signal and a second reference signal, the second reference signal being transmitted less frequently than the first reference signal; and

program code for causing the at least one processor to determine channel feedback information for the at least one bandwidth part based on the second reference signal, wherein the second reference signal comprises a channel state information reference signal.

15. A method for wireless communication, comprising:

transmitting a first reference signal;

transmitting a second reference signal, the second reference signal being transmitted less frequently than the first reference signal; and

receiving channel feedback information from a user equipment (UE), the channel feedback information being determined based on the second reference signal by the UE for at least one bandwidth part configured for the UE, each bandwidth part covering at least one subband among a plurality of subbands, each bandwidth part comprising less than an entire system bandwidth, wherein the second reference signal comprises a channel state information reference signal.

16. The method of claim 15, wherein the first reference signal comprises a cell-specific reference signal (CRS).

17. The method of claim 15, further comprising reducing transmission on one or more bandwidth parts, or in one or more subframes, or on one or more bandwidth parts in one or more subframes by a cell to reduce interference to at least one other second reference signal from at least one other cell.

18. An apparatus for wireless communication, comprising:

means for transmitting a first reference signal;

means for transmitting a second reference signal, the second reference signal being transmitted less frequently than the first reference signal; and

means for receiving channel feedback information from a user equipment (UE), the channel feedback information being determined based on the second reference signal by the UE for at least one bandwidth part configured for the UE, each bandwidth part covering at least one subband among a plurality of subbands, each bandwidth part comprising less than an entire system bandwidth, wherein the second reference signal comprises a channel state information reference signal.

19. An apparatus for wireless communication, comprising:

a memory unit;

at least one processor coupled to the memory unit, wherein the at least one processor is configured;

to transmit a first reference signal,

to transmit a second reference signal in a second set of subframes, the second reference signal being transmitted less frequently than the first reference signal, and to receive channel feedback information from a user equipment (UE), the channel feedback information being determined based on the second reference signal by the UE for at least one bandwidth part configured for the UE, each bandwidth part covering at least one subband among a plurality of subbands, each bandwidth part comprising less than an entire system bandwidth, wherein the second reference signal comprises a channel state information reference signal.

20. A computer program product for wireless communications, the computer program product comprising a non-transitory computer-readable medium having program code recorded thereon, the program code comprising:

program code for causing at least one processor to send a first reference signal;

program code for causing the at least one processor to send a second reference signal, the second reference signal being sent less frequently than the first reference signal; and

program for causing the at least one processor to receive channel feedback information from a user equipment (UE), the channel feedback information being determined based on the second reference signal by the UE for at least one bandwidth part configured for the UE, each bandwidth part covering at least one subband among a plurality of subbands, each bandwidth part comprising less than an entire system bandwidth, wherein the second reference signal comprises a channel state information reference signal.