Wireless communications system, wireless communications apparatus, wireless communications method and computer program for wireless communication

• US 8,249,002 B2
• Filed: 10/30/2008
• Issued: 08/21/2012
• Est. Priority Date: 11/05/2003
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Kuroda, Shinichi
• Primary Examiner(s): Taylor, Barry
• Application Number:
  US12/261,708
• Publication Number:
  US 20090059880A1
• Time in Patent Office: 1,391 Days
• Field of Search: 370/329, 370/334, 455/562.1
• US Class Current: 370/329
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04B 7/0421 utilizing implicit feedback, e.g. steered pilot signals
• CPC Class Codes: H04B 7/0456 Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
• CPC Class Codes: H04B 7/06 at the transmitting station
• CPC Class Codes: H04B 7/0619 using feedback from receiving side feedback signaling for adaptive modulation/coding H04L1/0001
• CPC Class Codes: H04B 7/0665 Feed forward of transmit weights to the receiver
• CPC Class Codes: H04B 7/0854 using error minimizing algorithms, e.g. minimum mean squared error [MMSE], "cross-correlation" or matrix inversion
• CPC Class Codes: H04B 7/0862 receiver computing weights based on information from the transmitter
• CPC Class Codes: H04L 1/0656 Cyclotomic systems, e.g. Bell Labs Layered Space-Time [BLAST]
• CPC Class Codes: H04L 2025/0377 during the reception of training signals
• CPC Class Codes: H04L 25/0202 Channel estimation
• CPC Class Codes: H04L 25/0224 using sounding signals
• CPC Class Codes: H04L 27/12 Modulator circuits; Transmitter circuits
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems
• CPC Class Codes: H04W 72/20 Control channels or signalling for resource management

Abstract

In performing SVD-MIMO transmission, a set-up procedure is simplified while assuring a satisfactory decoding capability with a reduced number of antennas. A transmitter estimates channel information based on reference signals sent from a receiver, determines a transmit antenna weighting coefficient matrix based on the channel information, calculates a weight to be assigned to each of components of a multiplexed signal, and sends, to the receiver, training signals for respective signal components, the training signals being weighted by the calculated weights. On the other hand, the receiver determines a receive antenna weighting coefficient matrix based on the received training signals.

Claims

1. A wireless communication apparatus for transmitting a signal by multiplexing the signal using a plurality of antennas, the apparatus comprising:

a channel information acquirer which obtains channel information representing a characteristic of a channel linking the apparatus to a receiver;

a matrix determiner which determines a weighting coefficient matrix for transmit antennas based on the obtained channel information;

a training signal sender which sends training signals for channel estimation at the receiver, the training signals being weighted by weights included in the weighting coefficient matrix determined by the matrix determiner.

2. The apparatus of claim 1, wherein the channel information acquirer estimates the channel information based on reference signals sent from the receiver, wherein a number of the reference signals is determined based on a number of antennas at the receiver.

3. The apparatus of claim 2, wherein the channel information acquirer calibrates the channel information obtained based on the reference signals sent from the receiver, to obtain the channel information in the direction from the apparatus to the receiver.

4. The apparatus of claim 2, which employs a RTS/CTS function where a transmitter sends a transmission requesting packet RTS (Request To Send) and initiates a data transfer in response to and upon receiving a confirmation packet CTS (Clear To Send) including the reference signals sent from a receiver,

wherein the channel information acquirer calculates a weight to be assigned to each of components of the multiplexed signal based on the channel information which is obtained based on the reference signals included in the CTS packet, and

wherein the training signal sender sends a data packet including training signals for respective signal components sent in a multiplexed fashion.

5. The apparatus of claim 1, wherein the matrix determiner determines the weighting coefficient matrix for the transmit antennas by performing one of maximal ratio combining, zero-forcing for canceling all unnecessary signals, a combination of maximal ratio combining and zero-forcing, and a singular value decomposition.

6. A method performed by a wireless communication apparatus for transmitting a signal by multiplexing the signal using a plurality of antennas, the method comprising:

obtaining channel information representing a characteristic of a channel linking the apparatus to a receiver;

determining a weighting coefficient matrix for transmit antennas based on the obtained channel information;

sending training signals for channel estimation at the receiver that are weighted by weights included in the weighting coefficient matrix determined in the determining.

7. The method of claim 6, wherein the obtaining includes estimating the channel information based on reference signals sent from the receiver, wherein a number of the reference signals is determined based on a number of antennas at the receiver.

8. The method according to claim 7, wherein the obtaining includes calibrating the channel information obtained based on the reference signals sent from the receiver, to obtain the channel information in the direction from the apparatus to the receiver.

9. The method according to claim 7, which employs a RTS/CTS process where a transmitter sends a transmission requesting packet RTS (Request To Send) and initiates a data transfer in response to and upon receiving a confirmation packet CTS (Clear To Send) including the reference signals sent from a receiver, wherein

the obtaining includes calculating a weight to be assigned to each of components of the multiplexed signal based on the channel information which is obtained based on the reference signals included in the CTS packet, and

the sending includes sending a data packet including training signals for respective signal components sent in a multiplexed fashion.

10. The method according to claim 6, wherein the determining includes determining the weighting coefficient matrix for the transmit antennas by performing one of maximal ratio combining, zero-forcing for canceling all unnecessary signals, a combination of maximal ratio combining and zero-forcing, and a singular value decomposition.