Apparatus and method for calibrating channel in radio communication system using multiple antennas

• US 20070064823A1
• Filed: 09/18/2006
• Published: 03/22/2007
• Est. Priority Date: 09/16/2005
• Status: Abandoned Application

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Choi, Soong-Yoon, Nam, Seung-Hoon, Chae, Chan-Byoung, Hwang, Gun-Chul
• Application Number:
  US11/523,279
• Publication Number:
  US 20070064823A1
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04B 17/24 with feedback of measurements to the transmitter
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0224 using sounding signals
• CPC Class Codes: H04L 5/1469 using time-sharing

Abstract

Provided is an apparatus and method for calibrating a channel in a radio communication system using multiple antennas. A base station apparatus for the radio communication system includes a channel estimator and a calculator. The channel estimator receives a UL sounding signal to estimate a first UL CSI and receives a UL sounding signal weighted with a DL CSI to estimate a second UL CSI. The calculator calculates calibration values for the respective antenna pairs using the first UL CSI and the second UL CSI. Information necessary for channel calibration is transmitted and received in an analog format. Accordingly, it is possible to minimize the waste of resource and time necessary for channel calibration.

Claims

1. A base station apparatus for a radio communication system using multiple antennas, the base station apparatus comprising:

a channel estimator for receiving a uplink (UL) sounding signal to estimate a first UL channel state information (CSI) and receiving a UL sounding signal weighted with a downlink (DL) CSI to estimate a second UL CSI; and

a calculator for calculating calibration values for the respective antenna pairs using the first UL CSI and the second UL CSI.

2. The base station apparatus of claim 1, further comprising a channel calibrator for calibrating the first UL CSI using the calibration values to obtain a calibrated channel response matrix.

3. The base station apparatus of claim 2, wherein the calibrated channel response matrix is used as a DL channel response matrix when the radio communication system is a Time Division Duplexing (TDD) communication system.

4. The base station apparatus of claim 2, further comprising:

a weight generator for generating a weight matrix for a TX vector on the basis of the calibrated channel response matrix; and

a weight multiplier for multiplying the TX vector by the weight matrix to generate a plurality of antenna signals.

5. The base station apparatus of claim 4, further comprising:

a plurality of IFFT processor for IFFT-processing the generated antenna signals; and

a plurality of RF processors for converting the IFFT-processed signals into RF signals to transmit the RS signals through the corresponding antennas.

6. The base station apparatus of claim 4, wherein the weight matrix generated by the weight generator is a codebook-based precoding matrix or a Singular Vector Decomposition (SVD)-based eigenvector matrix.

7. The base station apparatus of claim 1, wherein the calculator calculates calibration values C(i,j) for the i^th TX antenna and the j^th RX antenna using

$\mathrm{Equation}$

 

⁢

C ⁡

( i , j ) = H ⁡

( i , j ) ( H M →

B ⁡

( i , j ) ) 2

where H(i,j) and H<sub>M→

B</sub>(i,j) are the second UL CSI and the first UL CSI.

8. The base station apparatus of claim 1, further comprising a transmitter for transmitting a DL pilot signal used for estimating the DL CSI.

9. A mobile station apparatus for a radio communication system using multiple antennas, the mobile station apparatus comprising:

a channel estimator for estimating a downlink (DL) channel state information CSI using a DL pilot signal received from a base station;

a sounding signal generator for weighting a sounding signal with the DL CSI to generate a channel calibration sounding signal; and

a transmitter for transmitting the channel calibration sounding signal to the base station.

10. The mobile station apparatus of claim 9, wherein the transmitter comprises:

a plurality of IFFT processors for mapping the channel calibration sounding signal to a predetermined subcarrier position, IFFT-processing the resulting signal; and

a plurality of RF processors for converting the IFFT-processed signals into RF signals to transmit the RF signals through the corresponding antennas.

11. A method for operating a base station in a radio communication system using multiple antennas, the method comprising the steps of:

receiving a UL sounding signal to estimate a first UL CSI;

receiving a UL sounding signal weighted with a DL CSI to estimate a second UL CSI; and

calculating calibration values for the respective antenna pairs using the first UL CSI and the second UL CSI.

12. The method of claim 11, further comprising:

calibrating the first UL CSI using the calibration values to obtain a calibrated channel response matrix.

13. The method of claim 12, wherein the calibrated channel response matrix is used as a DL channel response matrix when the radio communication system is a TDD communication system.

14. The method of claim 12, further comprising:

generating a weight matrix for a TX vector on the basis of the calibrated channel response matrix; and

multiplying the TX vector by the weight matrix to generate a plurality of antenna signals.

15. The method of claim 14, further comprising:

processing the generated antenna signals to output the IFFT-processed signals; and

converting the IFFT-processed signals into RF signals to transmit the RF signals through the corresponding antennas.

16. The method of claim 14, wherein the weight matrix is a codebook-based preceding matrix or a SVD-based eigenvector matrix.

17. The method of claim 11, wherein calibration values C(i,j) for the i^th TX antenna and the j^th RX antenna are calculated using

$\mathrm{Equation}$

 

⁢

C ⁡

( i , j ) = H ⁡

( i , j ) ( H M →

B ⁡

( i , j ) ) 2

where H(i,j) and H<sub>M→

B</sub>(i,j) are the second UL CSI and the first UL CSI.

18. The method of claim 11, further comprising transmitting a DL pilot signal used for estimating the DL CSI.

19. A method for operating a mobile station in a radio communication system using multiple antennas, the method comprising the steps of:

receiving a DL pilot signal to estimate a DL CSI;

weighting a sounding signal with the DL CSI to generate a channel calibration sounding signal; and

transmitting the channel calibration sounding signal to a base station.

20. The method of claim 19, wherein the step of transmitting the channel calibration sounding signal further comprises:

mapping the channel calibration sounding signal to a predetermined subcarrier position, processing the resulting signal, and outputting the IFFT-processed signals; and

converting the IFFT-processed signals into RF signals to transmit the RF signals through the corresponding antennas.

21. A method for calibrating a channel in a radio communication system using multiple antennas, the method comprising the steps of:

estimating, at a transmitter, a first UL CSI using a UL sounding signal received from a receiver;

estimating, at the receiver, a DL CSI using a DL pilot signal received from the transmitter, weighting the UL sounding signal with the DL CSI, and transmitting the DL CSI-weighted sounding signal to the transmitter;

estimating, at the transmitter, a second UL CSI using the DL CSI-weighted sounding signal; and

calculating, at the transmitter, channel calibration values for the respective antenna pairs using the first UL CSI and the second UL CSI.

22. The method of claim 21, further comprising calibrating, at the transmitter, the first UL CSI using the calculated channel calibration values to obtain a calibrated channel response matrix.

23. The method of claim 22, wherein the calibrated channel response matrix is used as a DL channel response matrix when the radio communication system is a TDD communication system.

24. A mobile station apparatus for a radio communication system using multiple antennas, the mobile station apparatus comprising:

a channel estimator for receiving a downlink (DL) sounding signal to estimate a first DL channel state information (CSI) and receiving a DL sounding signal weighted with a uplink (UL) CSI to estimate a second DL CSI; and

a calculator for calculating calibration values for the respective antenna pairs using the first DL CSI and the second DL CSI.

25. A base station apparatus for a radio communication system using multiple antennas, the mobile station apparatus comprising:

a channel estimator for estimating a uplink (UL) CSI using a UL pilot signal received from a mobile station;

a sounding signal generator for weighting a sounding signal with the UL CSI to generate a channel calibration sounding signal; and

a transmitter for transmitting the channel calibration sounding signal to the mobile station.