APPARATUS AND METHOD FOR PRECODING BY MIDAMBLE IN MULTIPLE INPUT MULTIPLE OUTPUT WIRELESS COMMUNICATION SYSTEM

• US 20090262694A1
• Filed: 04/15/2009
• Published: 10/22/2009
• Est. Priority Date: 04/17/2008
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: HWANG, Keun-Chul, PARK, Sung-Woo, LEE, Sung-Ho
• Granted Patent: US 8,503,379 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04B 7/0621 Feedback content
• CPC Class Codes: H04B 7/0632 Channel quality parameters, e.g. channel quality indicator [CQI]
• CPC Class Codes: H04B 7/0634 Antenna weights or vector/matrix coefficients
• 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 25/0226 sounding signals per se
• CPC Class Codes: H04L 25/0244 with inversion
• CPC Class Codes: H04L 25/03343 Arrangements at the transmitter end
• CPC Class Codes: H04L 27/2613 Structure of the 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

Abstract

A method and apparatus for performing codebook-based precoding in a Multiple Input Multiple Output (MIMO) wireless communication system are provided. In a method for operating a Base Station (BS) in a MIMO wireless communication system, a reference signal including pilot signals, which are divided by a predefined number of bands and are multiplied by respective codes in a codebook, is transmitted. One or more Mobile Stations (MSs) destined for spatial multiple access are selected using an index of a band and CQI of the band corresponding to the index, which are fed back from one or more MSs. A precoding matrix is generated to process data streams of the selected one or more MSs.

Claims

1. A method for operating a Base Station (BS) in a Multiple Input Multiple Output (MIMO) wireless communication system, the method comprising:

transmitting reference signals including pilot signals that are divided by a predefined number of bands and are multiplied by respective codes in a codebook;

selecting one or more Mobile Stations (MSs) destined for spatial multiple access using an index of a band and Channel Quality Information (CQI) of the band corresponding to the index, which are fed back from one or more MSs; and

generating a precoding matrix for processing data streams of the selected one or more MSs.

2. The method of claim 1, wherein the transmitting of the reference signals comprises:

transmitting the reference signals sequentially while shifting the reference signals cyclically by the code in every frame.

3. The method of claim 1, wherein the selecting of the one or more MSs destined for spatial multiple access comprises:

classifying the fed-back CQI on a band/frame basis; and

selecting the one or more MSs having the maximum channel quality value in a same band as the one or more MSs destined for spatial multiple access in the band.

4. The method of claim 1, wherein the precoding matrix is generated using a matrix having one of codes and Hermitian vectors of codes used in the band when each of the selected one or more MSs feeds back an index of the band as a column vector.

5. The method of claim 4, wherein the precoding matrix is generated using the equation:

$P={G^H<br><br>\left({\mathrm{GG}}^H\right)}^{-1},G=\left[\begin{array}{c}{c}_1^H\\ c_4^H\\ c_3^H\\ c_2^H\end{array}\right]$

where P denotes the precoding matrix, G denotes a matrix having the Hermitian vectors of the codes as the column vector, c₁ denotes a first code, c₂ denotes a second code, c₃ denotes a third code, and c₄ denotes a fourth code.

6. The method of claim 1, further comprising:

transmitting data signals multiplied by the precoding matrix and dedicated pilot signals multiplied by the respective codes.

7. A method for operating a Mobile Station (MS) in a Multiple Input Multiple Output (MIMO) wireless communication system, the method comprising:

receiving a reference signal including pilot signals that are divided by a predefined number of bands and are multiplied by respective codes in a codebook;

measuring a band-by-band channel quality by using the reference signal; and

feeding back Channel Quality Information (CQI) and an index of the band with a maximum channel quality value to a Base Station (BS).

8. The method of claim 7, further comprising:

estimating, upon receipt of data signals and dedicated pilot signals, an effective channel by using the dedicated pilot signals; and

detecting the data signals by using the effective channel.

9. The method of claim 8, further comprising:

obtaining channel matrix information by multiplying an effective channel matrix by an inverse matrix of a precoding matrix used in the BS;

selecting a code in a codebook by using the channel matrix; and

feeding back an index of the selected code.

10. The method of claim 9, further comprising:

detecting codes applied to reference signals with reference to a frame number; and

generating a precoding matrix by using the detected codes.

11. An apparatus for a Base Station (BS) in a Multiple Input Multiple Output (MIMO) wireless communication system, the apparatus comprising:

a transmitter for transmitting a reference signal including pilot signals that are divided by a predefined number of bands and are multiplied by respective codes in a codebook;

a scheduler for selecting one or more Mobile Stations (MSs) destined for spatial multiple access by using an index of a band and Channel Quality Information (CQI) of the band corresponding to the index, which are fed back from one or more MSs; and

a generator for generating a precoding matrix for processing data streams of the selected one or more MSs.

12. The apparatus of claim 11, wherein the transmitter shifts the reference signals cyclically by the code, and transmits the reference signal sequentially through a plurality of frames.

13. The apparatus of claim 11, wherein the scheduler classifies the fed-back CQI on a band/frame basis, and selects the one or more MSs having the maximum channel quality value in a same band as the one or more MSs destined for spatial multiple access in the band.

14. The apparatus of claim 11, wherein the precoding matrix is generated using a matrix having one of codes and Hermitian vectors of codes used in the band when each of the selected one or more MSs feeds back an index of the band as a column vector.

15. The apparatus of claim 14, wherein the precoding matrix is generated using the equation:

$P={G^H<br><br>\left({\mathrm{GG}}^H\right)}^{-1},G=\left[\begin{array}{c}{c}_1^H\\ c_4^H\\ c_3^H\\ c_2^H\end{array}\right]$

where P denotes the precoding matrix, G denotes a matrix having the Hermitian vectors of the codes as the column vector, c₁ denotes a first code, c₂ denotes a second code, c₃ denotes a third code, and c₄ denotes a fourth code.

16. The apparatus of claim 11, wherein the transmitter transmits data signals multiplied by the precoding matrix and dedicated pilot signals multiplied by the respective codes.

17. An apparatus for a Mobile Station (MS) in a Multiple Input Multiple Output (MIMO) wireless communication system, the apparatus comprising:

a receiver for receiving a reference signal including pilot signals that are divided by a predefined number of bands and are multiplied by the respective codes in a codebook;

an estimator for measuring a band-by-band channel quality by using the reference signal; and

a processor for generating control information including Channel Quality Information (CQI) and an index of the band with the maximum channel quality value, which are to be transmitted to a Base Station (BS).

18. The apparatus of claim 17, wherein the estimator estimates, upon receipt of data signals and dedicated pilot signals, an effective channel by using the dedicated pilot signals, and the apparatus further comprises a detector for detecting the data signals by using the effective channel.

19. The apparatus of claim 18, further comprising:

a selector for obtaining channel matrix information by multiplying an effective channel matrix by an inverse matrix of a precoding matrix used in the BS, and for selecting a code in a codebook by using the channel matrix,

wherein the processor feeds back an index of the selected code to the BS.

20. The apparatus of claim 19, wherein the selector detects codes applied to reference signals with reference to a frame number, and generates a precoding matrix by using the detected codes.