Unified MIMO transmission and reception

• US 7,978,649 B2
• Filed: 07/15/2004
• Issued: 07/12/2011
• Est. Priority Date: 07/15/2004
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Walton, Jay Rodney, Howard, Steven J., Wallace, Mark S.
• Primary Examiner(s): Trost, IV; William
• Assistant Examiner(s): Shand; Roberta A
• Application Number:
  US10/892,732
• Publication Number:
  US 20060013250A1
• Time in Patent Office: 2,553 Days
• Field of Search: 370/328, 370/329, 370/334, 375/267
• US Class Current: 370/329
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/0421 utilizing implicit feedback, e.g. steered pilot signals
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication

Abstract

A “unified” MIMO system that supports multiple operating modes for efficient data transmission is described. Each operating mode is associated with different spatial processing at a transmitting entity. For example, four operating modes may be defined for (1) full-CSI or partial-CSI transmission and (2) with or without steering transmit diversity (STD). An appropriate operating mode may be selected for use based on various factors (e.g., availability of a good channel estimate). With steering transmit diversity, data is spatially spread and transmitted on multiple spatial channels, and a single rate may then be used for all spatial channels used for data transmission. A receiving entity may utilize a minimum mean square error (MMSE) technique for all operating modes. The receiving entity may derive a spatial filter matrix and perform receiver spatial processing in the same manner for all operating modes, albeit with different effective channel response matrices.

Claims

1. A method of receiving data in a multiple-input multiple-output (MIMO) communication system, comprising:

obtaining an effective channel response matrix for an effective MIMO channel observed by data symbols sent by a transmitting entity, wherein the system supports a plurality of operating modes, each operating mode being associated with different spatial processing on the data symbols by the transmitting entity, and wherein the effective MIMO channel includes a MIMO channel used for data transmission and the spatial processing, if any, performed by the transmitting entity on the data symbols;

deriving a spatial filter matrix based on the effective channel response matrix and in accordance with a minimum mean square error (MMSE) technique; and

performing spatial processing on symbols received via the MIMO channel with the spatial filter matrix to obtain estimates of the data symbols sent by the transmitting entity.

2. The method of claim 1, wherein the plurality of operating modes include an operating mode supporting data transmission on one or more spatial channels without any spatial processing by the transmitting entity, and wherein the effective channel response matrix is for the MIMO channel used for data transmission.

3. The method of claim 1, wherein the plurality of operating modes include an operating mode supporting data transmission on one or more spatial channels with steering transmit diversity, and wherein the effective channel response matrix comprises a channel response matrix for the MIMO channel and a steering matrix used for the steering transmit diversity.

4. The method of claim 1, wherein the plurality of operating modes include an operating mode supporting data transmission on one or more orthogonal spatial channels, and wherein the effective channel response matrix comprises a channel response matrix for the MIMO channel and an eigenmode matrix used to transmit the data symbols on the one or more orthogonal spatial channels.

5. The method of claim 1, wherein the plurality of operating modes include an operating mode supporting data transmission on one or more orthogonal spatial channels with steering transmit diversity, and wherein the effective channel response matrix comprises a channel response matrix for the MIMO channel, an eigenmode matrix used to transmit the data symbols on the one or more orthogonal spatial channels, and a steering matrix used for the steering transmit diversity.

6. The method of claim 1, wherein the spatial filter matrix is derived based on the following equation for the MMSE technique:

M_mmse=[H_eff^H·

H_eff+σ

²·

I]<sup>−

1</sup>·

H_eff^H,

where H_eff is the effective channel response matrix;

I is an identity matrix;

M_mmse is the spatial filter matrix;

σ

² is variance of noise; and

“

^H”

as is a conjugate transpose.

7. An apparatus in a wireless multiple-input multiple-output (MIMO) communication system, comprising:

a first processor operative to obtain an effective channel response matrix for an effective MIMO channel and to derive a spatial filter matrix based on the effective channel response matrix and in accordance with a minimum mean square error (MMSE) technique, wherein the system supports a plurality of operating modes, each operating mode being associated with different spatial processing on data symbols by a transmitting entity, and wherein the effective MIMO channel is observed by the data symbols sent by the transmitting entity and includes a MIMO channel used for data transmission and the spatial processing, if any, performed by the transmitting entity on the data symbols; and

a spatial processor operative to perform spatial processing on symbols received via the MIMO channel with the spatial filter matrix to obtain estimates of the data symbols sent by the transmitting entity.

8. The apparatus of claim 7, wherein the plurality of operating modes include an operating mode supporting data transmission on one or more spatial channels without any spatial processing by the transmitting entity, and wherein the effective channel response matrix is for the MIMO channel used for data transmission.

9. The apparatus of claim 7, wherein the plurality of operating modes include an operating mode supporting data transmission on one or more orthogonal spatial channels, and wherein the effective channel response matrix comprises a channel response matrix for the MIMO channel and an eigenmode matrix used to transmit the data symbols on the one or more orthogonal spatial channels.

10. An apparatus in a wireless multiple-input multiple-output (MIMO) communication system, comprising:

means for obtaining an effective channel response matrix for an effective MIMO channel observed by data symbols sent by a transmitting entity, wherein the system supports a plurality of operating modes, each operating mode being associated with different spatial processing on the data symbols by the transmitting entity, and wherein the effective MIMO channel includes a MIMO channel used for data transmission and the spatial processing, if any, performed by the transmitting entity on the data symbols;

means for deriving a spatial filter matrix based on the effective channel response matrix and in accordance with a minimum mean square error (MMSE) technique; and

means for performing spatial processing on symbols received via the MIMO channel with the spatial filter matrix to obtain estimates of the data symbols sent by the transmitting entity.

11. The apparatus of claim 10, wherein the plurality of operating modes include an operating mode supporting data transmission on one or more spatial channels without any spatial processing by the transmitting entity, and wherein the effective channel response matrix is for the MIMO channel used for data transmission.

12. The apparatus of claim 10, wherein the plurality of operating modes include an operating mode supporting data transmission on one or more orthogonal spatial channels, and wherein the effective channel response matrix comprises a channel response matrix for the MIMO channel and an eigenmode matrix used to transmit the data symbols on the one or more orthogonal spatial channels.

13. A memory appartus encoded with instructions executable by a processor for performing a method of receiving data in a multiple-input multiple-output (MIMO) communication system, the method comprising:

obtaining an effective channel response matrix for an effective MIMO channel observed by data symbols sent by a transmitting entity, wherein the system supports a plurality of operating modes, each operating mode being associated with different spatial processing on the data symbols by the transmitting entity, and wherein the effective MIMO channel includes a MIMO channel used for data transmission and the spatial processing, if any, performed by the transmitting entity on the data symbols;

deriving a spatial filter matrix based on the effective channel response matrix and in accordance with a minimum mean square error (MMSE) technique; and

performing spatial processing on symbols received via the MIMO channel with the spatial filter matrix to obtain estimates of the data symbols sent by the transmitting entity.

14. The apparatus of claim 13, wherein the plurality of operating modes include an operating mode supporting data transmission on one or more spatial channels without any spatial processing by the transmitting entity, and wherein the effective channel response matrix is for the MIMO channel used for data transmission.

15. The apparatus of claim 13, wherein the plurality of operating modes include an operating mode supporting data transmission on one or more orthogonal spatial channels, and wherein the effective channel response matrix comprises a channel response matrix for the MIMO channel and an eigenmode matrix used to transmit the data symbols on the one or more orthogonal spatial channels.