Antenna selection with RF imbalance

• US 20070224943A1
• Filed: 03/23/2006
• Published: 09/27/2007
• Est. Priority Date: 03/23/2006
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Inventors: Wang, Dong, Zhang, Jinyun, Zhang, Hongyuan, Molisch, Andreas, Gu, Daqing
• Granted Patent: US 7,917,107 B2
• Time in Patent Office: Days
• US Class Current: 455/69
• CPC Class Codes: H04B 7/061 using feedback from receiving side
• CPC Class Codes: H04B 7/0691 using subgroups of transmit antennas
• CPC Class Codes: H04B 7/0874 using subgroups of receive antennas
• CPC Class Codes: H04L 25/0242 using matrix methods

Abstract

A method for selecting antennas in a multiple-input, multiple-output wireless communications network that includes multiple stations is presented. Each station includes a set of transmit RF chains and a set of receive RF chains, and each RF chain is connectable to a set of antennas. A first station transmits a training frame for each possible subset of the set of antennas, and the set of transmit RF chains are connected to the subset of antennas according to a connection mapping rule while transmitting each training frame. A subchannel matrix is estimated in a second station for each frame. The subchannel matrices are combined to obtain a complete channel matrix. A particular subset of the antennas is selected according to the complete channel matrix. The set of transmit RF chains is connected to the selected particular subset of antennas to transmit data from the first station to the second station.

Claims

1. A method for selecting antennas in a multiple-input, multiple-output wireless communications network including a plurality of stations, each station including a set of transmit RF chains and a set of receive RF chains, wherein each RF chain is connectable to a set of antennas, comprising the steps of:

transmitting, from a first station to a second station, a training frame for each possible subset of the set of antennas, and wherein the set of transmit RF chains are connected to the subset of antennas according to a connection mapping rule while transmitting each training frame;

estimating, in the second station, a subchannel matrix for each frame;

combining the subchannel matrices to obtain a complete channel matrix;

selecting a particular subset of the antennas according to the complete channel matrix; and

connecting the set of transmit RF chains to the selected particular subset of antennas, to transmit data from the first station to the second station.

2. The method of claim 1, further comprising:

feeding back the subchannel matrices from the second station to the first station;

determining, in the first station, transmit RF imbalance correction coefficients based on the estimated subchannel matrices;

combining the subchannel matrices in the first station; and

selecting a particular subset of the antennas according to the complete channel matrix and the transmit RF imbalance correction coefficients.

3. The method of claim 2, further comprising:

multiplying a baseband signal with the RF imbalance correction coefficients corresponding to the set of transmit RF chains and the selected particular subset of antennas, in which the baseband signal carries the transmit data.

4. The method of claim 1, further comprising:

determining, in the second station, receive RF imbalance correction coefficients based on the estimated subchannel matrices; and

combining the subchannel matrices in the second station.

5. The method of claim 1, further comprising:

selecting, in the second station, a particular subset of antennas, connected to the set of receive RF chains according to the complete channel matrix, to receive the transmit data.

6. The method of claim 1, further comprising:

multiplying a baseband signal with the RF imbalance correction coefficients corresponding to the connection of RF chains and antennas over which the baseband signal is received.

7. The method of claim 1, further comprising:

determining a transmit RF imbalance correction coefficient for a connection between an l^th RF chain and an i^th antenna using channel state information, such that the connection has a fixed baseband RF response.

8. The method of claim 1, further comprising:

determining a receive RF imbalance correction coefficient for a connection between an l^th RF chain and an j^th antenna using channel state information, such that the connection has a fixed base band RF response.

9. The method of claim 1, further comprising:

transmitting, from the second station to the first station, a calibration training request.

10. The method of claim 2, further comprising:

averaging the transmit correction coefficients over a time period.

11. The method of claim 4, further comprising:

averaging the receive correction coefficients over a time period.

12. The method of claim 1, in which the network is an orthogonal frequency division multiplexing (OFDM) network.

13. The method of claim 12, further comprising:

performing a calibration procedure for each subcarrier of the OFDM network.

14. The method of claim 1, in which the RF chains have RF chain indices and the antennas have antenna indices, and a RF chain with smaller RF chain index always connects to an antenna with smaller antenna index.

15. The method of claim 1, further comprising:

determining RF imbalance correction coefficients based on the estimated subchannel matrices.