Transmit beamforming utilizing channel estimation matrix decomposition feedback in a wireless MIMO communication system

1. A method of providing forward channel matrix information within a communication system, the communication system having i) a first communication device having a first plurality of antennas and ii) a second communication device having a second plurality of antennas, the method comprising:

determining, at the second communication device, a channel estimation matrix H describing a forward channel in which a signal travels from the first communication device to the second communication device;

performing, at the second communication device, QR decomposition on the channel estimation matrix H to derive a unitary matrix Q and an upper triangular matrix R, such that H=QR;

transmitting, from the second communication device to the first communication device, only a portion of the upper triangular matrix R so that the first communication device can use the portion of the upper triangular matrix R to precode signals to be transmitted by the first communication device; and

further comprising either:

(a) quantizing matrix elements of the upper triangular matrix R to derive quantized matrix elements; and

encoding the quantized matrix elements with error correcting codes;

wherein transmitting only the portion of the upper triangular matrix R comprises transmitting, from the second communication device to the first communication device, the encoded quantized matrix elements, or

(b) further comprising normalizing matrix elements of the upper triangular matrix by a standard deviation of noise in the forward channel determined from a signal-to-noise calculation;

wherein transmitting only the portion of the upper triangular matrix R comprises transmitting, from the second communication device to the first communication device, all normalized diagonal and upper-diagonal matrix elements of the upper triangular matrix.

2. The method of claim 1 , wherein further comprising (a) or (b) comprises:

quantizing matrix elements of the upper triangular matrix R to derive quantized matrix elements; and

encoding the quantized matrix elements with error correcting codes;

wherein transmitting only the portion of the upper triangular matrix R comprises transmitting, from the second communication device to the first communication device, the encoded quantized matrix elements.

3. The method of claim 1 , wherein further comprising (a) or (b) comprises:

normalizing matrix elements of the upper triangular matrix by a standard deviation of noise in the forward channel determined from a signal-to-noise calculation;

wherein transmitting only the portion of the upper triangular matrix R comprises transmitting, from the second communication device to the first communication device, all normalized diagonal and upper-diagonal matrix elements of the upper triangular matrix.

4. A first communication device, comprising:

a controller configured to determine a channel estimation matrix H describing a forward channel in which a signal travels from a second communication device to the first communication device; and

a QR decomposition processor configured to perform QR decomposition on the channel estimation matrix H to derive a unitary matrix Q and an upper triangular matrix R, such that H=QR;

wherein the controller is configured to cause only a portion of the upper triangular matrix R to be transmitted to the second communication device so that the second communication device can use the portion of the upper triangular matrix R to precode signals to be transmitted by the first communication device, and

wherein the controller is configured to:

(a) quantize matrix elements of the upper triangular matrix R to derive quantized matrix elements,

encode the quantized matrix elements with error correcting codes; and

cause the encoded quantized matrix elements to be transmitted to the second communication device, or

(b) normalize matrix elements of the upper triangular matrix by a standard deviation of noise in the forward channel determined from a signal-to-noise calculation; and

cause all normalized diagonal and upper-diagonal matrix elements of the upper triangular matrix to be transmitted to the second communication device.

5. The first communication device of claim 4 , wherein the controller is configured to:

quantize matrix elements of the upper triangular matrix R to derive quantized matrix elements,

encode the quantized matrix elements with error correcting codes;

cause the encoded quantized matrix elements to be transmitted to the second communication device.

6. The first communication device of claim 4 , wherein the controller is configured to:

normalize matrix elements of the upper triangular matrix by a standard deviation of noise in the forward channel determined from a signal-to-noise calculation; and

cause all normalized diagonal and upper-diagonal matrix elements of the upper triangular matrix to be transmitted to the second communication device.

7. A method, the method comprising:

receiving, at a first communication device, only a portion of an upper triangular matrix R, wherein the upper triangular matrix R was generated at a second communication device by performing QR decomposition on a channel estimation matrix H such that H=QR and Q is a unitary matrix, and wherein the channel estimation matrix H describes a forward channel in which a signal travels from the first communication device to the second communication device;

developing, at the first communication device, a precoding matrix from the portion of the upper triangular matrix R; and

controlling, at the first communication device, transmission of a modulated signal via a first plurality of antennas using the developed precoding matrix, wherein one of:

(a) the portion of the upper triangular matrix R comprises encoded and quantized matrix coefficients,

(b) developing a precoding matrix comprises decomposing the upper triangular matrix R to develop the precoding matrix using singular value decomposition to derive a unitary matrix, a diagonal matrix and a conjugate transpose of the precoding matrix, or

(c) the portion of the upper triangular matrix R comprises matrix coefficients normalized to a standard deviation of noise in the forward channel.

8. The method of claim 7 , wherein the one of (a), (b), and (c) comprises (a).

9. The method of claim 7 , wherein the one of (a), (b), and (c) comprises (b).

10. The method of claim 7 , wherein the one of (a), (b), and (c) comprises (c).

11. A first communication device, comprising:

a beamforming network coupled to a plurality of transmission antennas;

a controller configured to control the beamforming network using a precoding matrix so as to produce a transmit gain pattern having one or more high gain lobes via a plurality of transmission antennas based on the precoding matrix; and

a precoding matrix calculator configured to develop a steering matrix from a portion of an upper triangular matrix R,

wherein only the portion of an upper triangular matrix R is received from a second communication device, wherein the upper triangular matrix R was generated at the second communication device by performing QR decomposition on a channel estimation matrix H such that H=QR and Q is a unitary matrix, and wherein the channel estimation matrix H describes a forward channel in which a signal travels from the first communication device to the second communication device, wherein one of:

(a) the portion of the upper triangular matrix R comprises encoded and quantized matrix coefficients,

(b) the precoding matrix calculator is configured to decompose the upper triangular matrix R to develop the precoding matrix using singular value decomposition to derive a unitary matrix, a diagonal matrix and a conjugate transpose of the precoding matrix, or

(c) the portion of the upper triangular matrix R comprises matrix coefficients normalized to a standard deviation of noise in the forward channel.

12. The first communication device of claim 11 , wherein the one of (a), (b), and (c) comprises (a).

13. The first communication device of claim 11 , wherein the one of (a), (b), and (c) comprises (b).

14. The first communication device of claim 11 , wherein the one of (a), (b), and (c) comprises (c).