Blind mechanism for estimation and correction of I/Q impairments

1. A method for blind estimation of receiver correction parameters, the method comprising:

(a) receiving complex samples of a complex baseband signal from a receiver;

(b) computing a value of cross-correlation between a I component of the complex samples and a Q component of the complex samples, wherein the cross-correlation is a time-domain cross correlation between the I component and the Q component;

(c) computing a mean square value I MS of the I component of the complex samples, and computing a mean square value Q MS of the Q component of the complex samples;

(d) computing an estimate for a cross-channel gain k based on the cross-correlation value and one or both of the mean square values I MS and Q MS ;

(e) applying a cross-channel gain correction to the complex samples based on the estimate for the cross-channel gain k, in order to obtain modified complex samples;

(f) computing an estimate of a gain imbalance based on the mean square values I MS and Q MS , wherein the gain imbalance estimate is useable to correct an I/Q gain imbalance present in the complex samples;

computing an estimate of an I-channel DC offset based on the I component of the complex samples;

computing an estimate of a Q-channel DC offset based on the Q component of the complex samples; and

applying DC offset corrections to the complex samples of the complex baseband signal based on the estimate of the I-channel DC offset and the estimate of the Q-channel DC offset.

2. The method of claim 1 , wherein the receiver generates the complex baseband signal in response to receiving a signal transmission from a transmitter.

3. The method of claim 2 , wherein the signal transmission from the transmitter is a transmission of one or more of the following:

a modulated waveform;

a tone;

a series of tones;

a noise signal;

an interfering signal.

4. The method of claim 2 , wherein the cross-channel gain k represents cross-channel distortions in the transmitter and receiver, wherein the gain imbalance represents gain imbalance distortions in the transmitter and receiver.

5. The method of claim 1 , further comprising:

applying an I/Q gain imbalance correction to the modified complex samples based on the gain imbalance estimate to obtain corrected complex samples for the complex baseband signal.

6. The method of claim 5 , further comprising:

displaying the corrected complex samples.

7. The method of claim 1 , wherein the receiver generates the complex baseband signal in response to receiving a signal transmission from a transmitter, wherein the I-channel DC offset represents DC offset distortions in the I channel of the transmitter and the I channel of the receiver, wherein the Q-channel DC offset represents DC offset distortions in the Q channel of the transmitter and the Q channel of the receiver.

8. The method of claim 1 , wherein said applying the DC offset corrections to the complex samples is performed prior to performing (b) through (f).

9. The method of claim 1 , wherein (a) through (f) are performed by a computer external to the receiver, wherein the estimate for the cross-channel gain k and the gain imbalance value are stored in a memory of the computer.

10. The method of claim 9 , further comprising:

transferring the estimate of the cross-channel gain k and the gain imbalance estimate from the memory to the receiver, enabling the receiver to apply cross-channel gain correction and gain imbalance correction in an online operational mode of the receiver.

11. The method of claim 10 , wherein the receiver includes a programmable hardware element configured to apply said cross-channel gain correction and said gain imbalance correction based respectively on the estimate of the cross-channel gain and the gain imbalance estimate.

12. The method of claim 1 , further comprising:

supplying complex samples of a complex input signal to a transmitter; and

directing the transmitter to perform the signal transmission based on the complex samples of the complex input signal.

13. The method of claim 12 , wherein the complex input signal is a digitally-modulated baseband signal.

14. The method of claim 1 , wherein (a) through (f) are performed by the receiver.

15. The method of claim 1 , wherein the receiver generates the complex baseband signal in response to receiving a signal transmission from a transmitter, wherein the transmitter is a base station of a wireless communication network, wherein the signal transmission from the transmitter is a communication signal transmitted by the base station.

16. The method of claim 1 , wherein the receiver is incorporated in a wireless communication device.

17. A non-transitory computer-readable memory medium storing program instructions, wherein the program instructions, when executed by a processor, cause the processor to implement:

(a) receiving complex samples of a complex baseband signal from a receiver;

(b) computing a value of cross-correlation between a I component of the complex samples and a Q component of the complex samples, wherein the cross-correlation is a time-domain cross correlation between the I component and the Q component;

(c) computing a mean square value I MS of the I component of the complex samples, and computing a mean square value Q MS of the Q component of the complex samples;

(d) computing an estimate for a cross-channel gain k based on the cross-correlation value and one or both of the mean square values I MS and Q MS ;

(e) applying a cross-channel gain correction to the complex samples based on the estimate for the cross-channel gain k, in order to obtain modified complex samples;

(f) computing an estimate of a gain imbalance based on the mean square values I MS and Q MS , wherein the gain imbalance estimate is useable to correct an I/Q gain imbalance present in the complex samples;

computing an estimate of an I-channel DC offset based on the I component of the complex samples;

computing an estimate of a Q-channel DC offset based on the Q component of the complex samples; and

applying DC offset corrections to the complex samples of the complex baseband signal based on the estimate of the I-channel DC offset and the estimate of the Q-channel DC offset.

18. The memory medium of claim 17 , wherein the program instructions, when executed by the processor, further cause the processor to implement:

applying an I/Q gain imbalance correction to the modified complex samples based on the gain imbalance estimate to obtain corrected complex samples for the complex baseband signal.

19. A system comprising:

a processor; and

a memory storing program instructions, wherein the program instructions, when executed by the processor, cause the processor to:

(a) receiving complex samples of a complex baseband signal from a receiver;

(b) computing a value of cross-correlation between a I component of the complex samples and a Q component of the complex samples, wherein the cross-correlation is a time-domain cross correlation between the I component and the Q component;

(c) computing a mean square value I MS of the I component of the complex samples, and computing a mean square value Q MS of the Q component of the complex samples;

(d) computing an estimate for a cross-channel gain k based on the cross-correlation value and one or both of the mean square values I MS and Q MS ;

(e) applying a cross-channel gain correction to the complex samples based on the estimate for the cross-channel gain k, in order to obtain modified complex samples;

(f) computing an estimate of a gain imbalance based on the mean square values I MS and Q MS , wherein the gain imbalance estimate is useable to correct an I/Q gain imbalance present in the complex samples;

computing an estimate of an I-channel DC offset based on the I component of the complex samples;

computing an estimate of a Q-channel DC offset based on the Q component of the complex samples; and

applying DC offset corrections to the complex samples of the complex baseband signal based on the estimate of the I-channel DC offset and the estimate of the Q-channel DC offset.