FEEDBACK AND RATE ADAPTATION FOR MIMO TRANSMISSION IN A TIME DIVISION DUPLEXED (TDD) COMMUNICATION SYSTEM

• US 20090046800A1
• Filed: 07/29/2008
• Published: 02/19/2009
• Est. Priority Date: 08/13/2007
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Xu, Hao, Malladi, Durga Prasad
• Granted Patent: US 8,798,183 B2
• Time in Patent Office: Days
• US Class Current: 375/267
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0632 Channel quality parameters, e.g. channel quality indicator [CQI]
• CPC Class Codes: H04B 7/0639 Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
• CPC Class Codes: H04B 7/10 Polarisation diversity; Directional diversity
• CPC Class Codes: H04L 1/0001 Systems modifying transmission characteristics according to link quality, e.g. power backoff adaptive data allocation for multicarrier modulation H04L5/0044; controlling transmission power for radio systems H04W52/04
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 2025/03414 Multicarrier
• CPC Class Codes: H04L 2025/03426 transmission using multiple-input and multiple-output channels
• CPC Class Codes: H04L 2025/03802 Signalling on the reverse channel
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0228 with direct estimation from sounding signals
• CPC Class Codes: H04L 25/0248 Eigen-space methods
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end
• CPC Class Codes: H04L 25/0398 Restoration of channel reciprocity
• CPC Class Codes: H04L 27/0008 arrangements for allowing a transmitter or receiver to use more than one type of modulation negotiating modulation type for two-way transmission paths H04L5/1453
• CPC Class Codes: H04L 27/0012 arrangements for identifying the type of modulation
• CPC Class Codes: H04L 27/261 Details of reference signals
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0051 : of dedicated pilots, i.e. pilots destined for a single user or terminal
• CPC Class Codes: H04L 5/0053 : Allocation of signaling, i.e. of overhead other than pilot signals

Abstract

Techniques for sending a MIMO transmission in a wireless communication system are described. In one design, a transmitter sends a first reference signal to a receiver. The receiver selects a precoding matrix based on the first reference signal and in accordance with a selection criterion. The receiver estimates noise and interference at the receiver and determines channel quality indicator (CQI) or modulation and coding scheme (MCS) information based on the precoding matrix and the estimated noise and interference. The receiver sends the CQI or MCS information and a second reference signal to the transmitter. The transmitter selects the precoding matrix based on the second reference signal and in accordance with the same selection criterion used by the receiver. The transmitter then sends a MIMO transmission to the receiver based on the CQI or MCS information obtained from the receiver and the precoding matrix selected by the transmitter.

Claims

1. A method of transmitting data in a wireless communication system, comprising:

sending a first reference signal from a transmitter to a receiver;

receiving channel quality indicator (CQI) or modulation and coding scheme (MCS) information from the receiver;

receiving a second reference signal from the receiver;

selecting a precoding matrix based on the second reference signal; and

sending a multiple-input multiple-output (MIMO) transmission to the receiver based on the CQI or MCS information and the precoding matrix.

2. The method of claim 1, wherein the precoding matrix is selected by the receiver based on the first reference signal, and wherein the CQI or MCS information is determined by the receiver based on the precoding matrix and estimated noise and interference at the receiver.

3. The method of claim 1, wherein the selecting the precoding matrix comprises selecting the precoding matrix in accordance with a selection criterion also used by the receiver to select the precoding matrix.

4. The method of claim 1, wherein the selecting the precoding matrix comprises

obtaining a MIMO channel matrix based on the second reference signal,

obtaining a beamforming matrix based on the MIMO channel matrix, and

selecting the precoding matrix from a codebook of precoding matrices based on the beamforming matrix.

5. The method of claim 4, wherein the obtaining the beamforming matrix comprises performing singular value decomposition or eigenvalue decomposition of the MIMO channel matrix to obtain the beamforming matrix.

6. The method of claim 4, wherein the selecting the precoding matrix from the codebook comprises selecting the precoding matrix from the codebook based on the beamforming matrix and in accordance with a selection criterion of closest distance between the beamforming matrix and the precoding matrix.

7. The method of claim 1, wherein the sending the MIMO transmission comprises

obtaining S CQI values or S MCS values for S symbol streams from the CQI or MCS information, where S is one or greater, and

encoding and modulating the S symbol streams in accordance with the S CQI values or the S MCS values.

8. The method of claim 1, wherein the sending the MIMO transmission comprises performing precoding for S symbol streams based on the precoding matrix, where S is one or greater.

9. The method of claim 1, wherein the MIMO transmission is sent on downlink, wherein the transmitter is part of a Node B and the receiver is part of a user equipment (UE), and wherein the first reference signal comprises a downlink reference signal and the second reference signal comprises a sounding reference signal.

10. The method of claim 1, wherein the MIMO transmission is sent on uplink, wherein the transmitter is part of a user equipment (UE) and the receiver is part of a Node B, and wherein the first reference signal comprises a sounding reference signal and the second reference signal comprises a downlink reference signal.

11. An apparatus for wireless communication, comprising:

at least one processor configured to send a first reference signal from a transmitter to a receiver, to receive channel quality indicator (CQI) or modulation and coding scheme (MCS) information from the receiver, to receive a second reference signal from the receiver, to select a precoding matrix based on the second reference signal, and to send a multiple-input multiple-output (MIMO) transmission to the receiver based on the CQI or MCS information and the precoding matrix.

12. The apparatus of claim 11, wherein the at least one processor is configured to select the precoding matrix in accordance with a selection criterion also used by the receiver to select the precoding matrix.

13. The apparatus of claim 11, wherein the at least one processor is configured to obtain a MIMO channel matrix based on the second reference signal, to obtain a beamforming matrix based on the MIMO channel matrix, and to select the precoding matrix from a codebook of precoding matrices based on the beamforming matrix.

14. The apparatus of claim 11, wherein the at least one processor is configured to obtain S CQI values or S MCS values for S symbol streams from the CQI or MCS information, where S is one or greater, to encode and modulate the S symbol streams in accordance with the S CQI values or the S MCS values, and to perform precoding for the S symbol streams based on the precoding matrix.

15. An apparatus for wireless communication, comprising:

means for sending a first reference signal from a transmitter to a receiver;

means for receiving channel quality indicator (CQI) or modulation and coding scheme (MCS) information from the receiver;

means for receiving a second reference signal from the receiver;

means for selecting a precoding matrix based on the second reference signal; and

means for sending a multiple-input multiple-output (MIMO) transmission to the receiver based on the CQI or MCS information and the precoding matrix.

16. The apparatus of claim 15, wherein the means for selecting the precoding matrix comprises means for selecting the precoding matrix in accordance with a selection criterion also used by the receiver to select the precoding matrix.

17. The apparatus of claim 15, wherein the means for selecting the precoding matrix comprises

means for obtaining a MIMO channel matrix based on the second reference signal,

means for obtaining a beamforming matrix based on the MIMO channel matrix, and

means for selecting the precoding matrix from a codebook of precoding matrices based on the beamforming matrix.

18. The apparatus of claim 15, wherein the means for sending the MIMO transmission comprises

means for obtaining S CQI values or S MCS values for S symbol streams from the CQI or MCS information, where S is one or greater,

means for encoding and modulating the S symbol streams in accordance with the S CQI values or the S MCS values, and

means for performing precoding for the S symbol streams based on the precoding matrix.

19. A computer program product, comprising:

a computer-readable medium comprising;

code for causing at least one computer to send a first reference signal from a transmitter to a receiver,

code for causing at least one computer to receive channel quality indicator (CQI) or modulation and coding scheme (MCS) information from the receiver,

code for causing at least one computer to receive a second reference signal from the receiver,

code for causing the at least one computer to select a precoding matrix based on the second reference signal, and

code for causing the at least one computer to send a multiple-input multiple-output (MIMO) transmission to the receiver based on the CQI or MCS information and the precoding matrix.

20. A method of receiving data in a wireless communication system, comprising:

receiving a first reference signal from a transmitter at a receiver;

selecting a precoding matrix based on the first reference signal;

determining channel quality indicator (CQI) or modulation and coding scheme (MCS) information based on the precoding matrix;

sending the CQI or MCS information to the transmitter;

sending a second reference signal to the transmitter; and

receiving a multiple-input multiple-output (MIMO) transmission sent by the transmitter based on the CQI or MCS information and the precoding matrix, the precoding matrix being selected by the transmitter based on the second reference signal.

21. The method of claim 20, wherein the selecting the precoding matrix comprises selecting the precoding matrix in accordance with a selection criterion also used by the transmitter to select the precoding matrix.

22. The method of claim 20, wherein the selecting the precoding matrix comprises

obtaining a MIMO channel matrix based on the first reference signal,

obtaining a beamforming matrix based on the MIMO channel matrix, and

selecting the precoding matrix from a codebook of precoding matrices based on the beamforming matrix.

23. The method of claim 22, wherein the selecting the precoding matrix from the codebook comprises selecting the precoding matrix from the codebook based on the beamforming matrix and in accordance with a selection criterion of closest distance between the beamforming matrix and the precoding matrix.

24. The method of claim 20, wherein the determining the CQI or MCS information comprises

estimating noise and interference at the receiver, and

determining the number of symbol streams to send and the CQI or MCS information for the symbol streams based on the precoding matrix and the estimated noise and interference.

25. The method of claim 24, wherein the determining the CQI or MCS information further comprises determining the number of symbol streams to send and the CQI or MCS information for the symbol streams based further on a difference between transmit power for downlink and transmit power for uplink.

26. The method of claim 20, further comprising:

obtaining a MIMO channel matrix based on the first reference signal;

deriving a detection matrix based on the MIMO channel matrix and the precoding matrix; and

performing MIMO detection for the received MIMO transmission based on the detection matrix.

27. The method of claim 20, further comprising:

demodulating and decoding S symbol streams sent in the received MIMO transmission in accordance with S CQI values or S MCS values from the CQI or MCS information, where S is one or greater.

28. The method of claim 20, wherein the MIMO transmission is received on downlink, wherein the transmitter is part of a Node B and the receiver is part of a user equipment (UE), and wherein the first reference signal comprises a downlink reference signal and the second reference signal comprises a sounding reference signal.

29. The method of claim 20, wherein the MIMO transmission is received on uplink, wherein the transmitter is part of a user equipment (UE) and the receiver is part of a Node B, and wherein the first reference signal comprises a sounding reference signal and the second reference signal comprises a downlink reference signal.

30. An apparatus for wireless communication, comprising:

at least one processor configured to receive a first reference signal from a transmitter at a receiver, to select a precoding matrix based on the first reference signal, to determine channel quality indicator (CQI) or modulation and coding scheme (MCS) information based on the precoding matrix, to send the CQI or MCS information to the transmitter, to send a second reference signal to the transmitter, and to receive a multiple-input multiple-output (MIMO) transmission sent by the transmitter based on the CQI or MCS information and the precoding matrix, the precoding matrix being selected by the transmitter based on the second reference signal.

31. The apparatus of claim 30, wherein the at least one processor is configured to select the precoding matrix in accordance with a selection criterion also used by the transmitter to select the precoding matrix.

32. The apparatus of claim 30, wherein the at least one processor is configured to obtain a MIMO channel matrix based on the first reference signal, to obtain a beamforming matrix based on the MIMO channel matrix, and to select the precoding matrix from a codebook of precoding matrices based on the beamforming matrix.

33. The apparatus of claim 30, wherein the at least one processor is configured to estimate noise and interference at the receiver, and to determine the number of symbol streams to send and the CQI or MCS information for the symbol streams based on the precoding matrix and the estimated noise and interference.

34. An apparatus for wireless communication, comprising:

means for receiving a first reference signal from a transmitter at a receiver;

means for selecting a precoding matrix based on the first reference signal;

means for determining channel quality indicator (CQI) or modulation and coding scheme (MCS) information based on the precoding matrix;

means for sending the CQI or MCS information to the transmitter;

means for sending a second reference signal to the transmitter; and

means for receiving a multiple-input multiple-output (MIMO) transmission sent by the transmitter based on the CQI or MCS information and the precoding matrix, the precoding matrix being selected by the transmitter based on the second reference signal.

35. The apparatus of claim 34, wherein the means for selecting the precoding matrix comprises means for selecting the precoding matrix in accordance with a selection criterion also used by the transmitter to select the precoding matrix.

36. The apparatus of claim 34, wherein the means for selecting the precoding matrix comprises

means for obtaining a MIMO channel matrix based on the first reference signal,

means for obtaining a beamforming matrix based on the MIMO channel matrix, and

means for selecting the precoding matrix from a codebook of precoding matrices based on the beamforming matrix.

37. The apparatus of claim 34, wherein the means for determining the CQI or MCS information comprises

means for estimating noise and interference at the receiver, and

means for determining the number of symbol streams to send and the CQI or MCS information for the symbol streams based on the precoding matrix and the estimated noise and interference.

38. A computer program product, comprising:

a computer-readable medium comprising;

code for causing at least one computer to receive a first reference signal from a transmitter at a receiver,

code for causing at least one computer to select a precoding matrix based on the first reference signal,

code for causing the at least one computer to determine channel quality indicator (CQI) or modulation and coding scheme (MCS) information based on the precoding matrix,

code for causing the at least one computer to send the CQI or MCS information to the transmitter,

code for causing the at least one computer to send a second reference signal to the transmitter, and

code for causing the at least one computer to receive a multiple-input multiple-output (MIMO) transmission sent by the transmitter based on the CQI or MCS information and the precoding matrix, the precoding matrix being selected by the transmitter based on the second reference signal.