Active antenna array and method for calibration of the active antenna array

1. An active antenna array for mobile communications network comprising:

a plurality of receive paths carrying receive signals;

a sounding signal generator for generating a sounding signal for sounding at least a portion of at least one of the plurality of receive paths;

a coupler for coupling the sounding signal into at least one of the plurality of receive paths;

a sounding signal extractor for substantially removing the sounding signal from digitised ones of the receive signals to form a wanted signal.

2. The active antenna array of claim 1 , further comprising a power controller for controlling the level of power of the sounding signal.

3. The active antenna array of claim 1 , further comprising a controller for adjusting the characteristics of the sounding signal.

4. The active antenna array of claim 1 , further comprising a controller for adjusting the characteristics of the digitised receive signals.

5. The active antenna array of claim 1 , further comprising a correlator for correlating, in the digital domain, the sounding signal with at least one of the plurality of digitised receive signals, to form an error signal.

6. The active antenna array of claim 1 , further comprising a controller for adjusting characteristics of one of the plurality of digitised receive signals and the coupled sounding signal, in order to substantially eliminate the sounding signal in the one of the plurality of digitised receive signals, following subtraction of the sounding signal.

7. The active antenna array of claim 6 , further comprising a correlator for correlating, in the digital domain, the sounding signal with at least one of the plurality of digitised receive signals, to form an error signal, whereby the controller is adapted to adjust the characteristics in response to the error signal.

8. The active antenna array of claim 7 , whereby the controller is adapted to adjust the characteristics in response to one of in-phase and quadrature (I, Q) characteristics of the error signal or magnitude and phase characteristics of the error signal.

9. The active antenna array of claim 1 , further comprising a controller for adjusting characteristics of the sounding signal, in order to substantially eliminate the sounding signal in the one of the plurality of digitised receive signals, following subtraction of the sounding signal.

10. The active antenna array of claim 9 , further comprising a correlator for correlating, in the digital domain, the sounding signal with at least one of the plurality of digitised receive signals, to form an error signal, whereby the controller is adapted to adjust the characteristics of the sounding signal in response to the error signal.

11. The active antenna array of claim 10 , whereby the controller is adapted to adjust the characteristics in response to one of in-phase and quadrature (I, Q) characteristics of the error signal or magnitude and phase characteristics of the error signal.

12. The active antenna array of claim 1 , further comprising a calibration coefficient generator.

13. A computer program product comprising a non-transitory computer usable medium having control logic stored therein for causing a computer to manufacture an active antenna array comprising:

a plurality of receive paths carrying receive signals;

a sounding signal generator for generating a sounding signal for sounding at least a portion of at least one of the plurality of receive paths;

a coupler for coupling the sounding signal into at least one of the plurality of receive paths;

a sounding signal extractor for substantially removing the sounding signal from digitised ones of the receive signals to form a wanted signal.