Eigen-beamforming for wireless communication systems

A method of transmitting data in a wireless communication system, comprising:

• sending a first reference signal via a first link to a receiver;
• receiving channel quality indicator (CQI) information determined by the receiver based on the first reference signal;
• receiving a second reference signal via a second link from the receiver;
• obtaining at least one multiple-input multiple-output (MIMO) channel matrix for the first link based on the second reference signal received via the second link;
• determining at least one precoding matrix based on the at least one MIMO channel matrix;
• and
• sending a data transmission to the receiver based on the at least one precoding matrix and the CQI information,
• wherein one of the first and second reference signals is generated based on a pseudo-random sequence, and wherein the other one of the first and second reference signals is generated based on a constant amplitude zero auto correlation (CAZAC) sequence.

A method of transmitting data in a wireless communication system, comprising:

• sending a first reference signal via a first link to a receiver;
• receiving channel quality indicator (CQI) information determined by the receiver based on the first reference signal;
• receiving a second reference signal via a second link from the receiver;
• obtaining at least one multiple-input multiple-output (MIMO) channel matrix for the first link based on the second reference signal received via the second link;
• determining at least one precoding matrix based on the at least one MIMO channel matrix;
• and
• sending a data transmission to the receiver based on the at least one precoding matrix and the CQI information,
• wherein the sending the first reference signal comprises sending the first reference signal on subcarriers separated by a first spacing, and wherein the receiving the second reference signal comprises receiving the second reference signal on subcarriers separated by a second spacing different from the first spacing.

An apparatus for wireless communication, comprising:

• means for sending a first reference signal via a first link to a receiver;
• means for receiving channel quality indicator (CQI) information determined by the receiver based on the first reference signal;
• means for receiving a second reference signal via a second link from the receiver;
• means for obtaining at least one multiple-input multiple-output (MIMO) channel matrix for the first link based on the second reference signal received via the second link;
• means for determining at least one precoding matrix based on the at least one MIMO channel matrix;
• and
• means for sending a data transmission to the receiver based on the at least one precoding matrix and the CQI information,
• wherein the means for determining the at least one precoding matrix comprises:
• means for forming at least one pseudo-beam matrix based on the at least one MIMO channel matrix;
• means for performing QR decomposition of the at least one pseudo-beam matrix to obtain at least one matrix of orthogonal vectors;
• and
• means for determining the at least one precoding matrix based on the at least one matrix of orthogonal vectors.

A computer program product, comprising:

• a non-transitory computer-readable medium comprising:
• code for causing at least one computer to send a first reference signal via a first link to a receiver,
• code for causing the at least one computer to receive channel quality indicator (CQI) information determined by the receiver based on the first reference signal,
• code for causing the at least one computer to receive a second reference signal via a second link from the receiver,
• code for causing the at least one computer to obtain at least one multiple-input multiple-output (MIMO) channel matrix for the first link based on the second reference signal received via the second link,
• code for causing the at least one computer to determine at least one precoding matrix based on the at least one MIMO channel matrix, and
• code for causing the at least one computer to send a data transmission to the receiver based on the at least one precoding matrix and the CQI information,
• wherein the code for causing the at least one computer to determine the at least one precoding matrix comprises:
• code for causing the computer to form at least one pseudo-beam matrix based on the at least one MIMO channel matrix;
• code for causing the computer to perform QR decomposition of the at least one pseudo-beam matrix to obtain at least one matrix of orthogonal vectors;
• and
• code for causing the computer to determine the at least one precoding matrix based on the at least one matrix of orthogonal vectors.

A method of receiving data in a wireless communication system, comprising:

• receiving a first reference signal via a first link from a transmitter;
• determining channel quality indicator (CQI) information based on the first reference signal;
• sending the CQI information to the transmitter;
• sending a second reference signal via a second link;
• and
• receiving a data transmission sent by the transmitter based on the CQI information and at least one precoding matrix determined by the transmitter based on the second reference signal;
• obtaining at least one multiple-input multiple-output (MIMO) channel matrix based on the first reference signal;
• forming at least one pseudo-beam matrix based on the at least one MIMO channel matrix;
• performing QR decomposition of the at least one pseudo-beam matrix to obtain at least one matrix of orthogonal vectors;
• and
• determining at least one precoding matrix based on the at least one matrix of orthogonal vectors, and wherein the determining the CQI information comprises determining the CQI information based on the at least one precoding matrix.

A method of receiving data in a wireless communication system, comprising:

• receiving a first reference signal via a first link from a transmitter;
• determining channel quality indicator (CQI) information based on the first reference signal;
• sending the CQI information to the transmitter;
• sending a second reference signal via a second link;
• and
• receiving a data transmission sent by the transmitter based on the CQI information and at least one precoding matrix determined by the transmitter based on the second reference signal,
• wherein one of the first and second reference signals is generated based on a pseudo-random sequence, and wherein the other one of the first and second reference signals is generated based on a constant amplitude zero auto correlation (CAZAC) sequence.