Antenna selection with RF imbalance

• US 7,917,107 B2
• Filed: 03/23/2006
• Issued: 03/29/2011
• Est. Priority Date: 03/23/2006
• Status: Expired due to Fees

• 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, Molisch, Andreas F., Zhang, Hongyuan, Gu, Daqing
• Primary Examiner(s): Maung; Nay
• Assistant Examiner(s): PEREZ, ANGELICA
• Application Number:
  US11/387,252
• Publication Number:
  US 20070224943A1
• Time in Patent Office: 1,832 Days
• Field of Search: 455/41.1, 455/69, 455/101, 455/562.1, 455/277.1, 455/78, 455/103, 455/132, 455/140, 235/380, 235/462.46, 375/299, 375/261, 375/267, 375/347, 370/203, 370/208, 370/319, 370/344
• US Class Current: 455/132
• 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 during training, 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;

feeding back, from the second station to the first station, the subchannel matrix for each frame;

determining, in the first station, radio frequency (RF) imbalance transmit correction coefficients based on the subchannel matrices fed back by the second station, wherein the first station A has the set of N_A antennas with N<sub>A—

SS</sub> transmit RF chains, and the second station B has the set of N_B antennas with N<sub>B—

SS</sub> receive RF chains, and wherein the RF imbalance receive correction coefficients are determined as

2. The method of claim 1, further comprising:

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

multiplying the baseband stream received by selected receive antennas at the second station by the RF imbalance receive correction coefficients.

3. The method of claim 1, further comprising:

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

4. The method of claim 1, further comprising:

averaging the RF imbalance transmit correction coefficients over a time period.

5. The method of claim 2, further comprising:

averaging the RF imbalance receive correction coefficients over a time period.

6. The method of claim 1, further comprising:

performing a calibration procedure to reduce an RF imbalance at the first station.

7. 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.

8. The method of claim 1, further comprising:

correcting an RF imbalance using the RF imbalance transmit correction coefficients.

9. The method of claim 8, wherein the selected antennas are connected to different RF chains during data transmission and the training to cause the RF imbalance.