Method and apparatus for robust estimation of directions of arrival for antenna arrays

In an antenna array comprising a plurality of antenna elements, wherein a plurality of incident signals are received at said antenna array, a method for deriving a direction of arrival (DOA) estimate for one of said plurality of incident signals, said method comprising the steps of:

• downconverting said plurality of incident signals into a plurality of digital received signals;
• determining, by a digital beamformer, a plurality of digital baseband signals from said plurality of digital received signals;
• and
• processing, by a direction of arrival estimator (DOAE), said plurality of digital baseband signals.

A direction of arrival (DOA)-aided digital beamforming (DBF) subsystem comprising:

• at least one antenna array having a plurality of elements;
• a plurality of receive/transmit (Rx/Tx) modules coupled to said plurality of elements;
• a digital beamformer (DBF) coupled to said plurality of Rx/Tx modules, said DBF controlling N elements of said plurality of elements to establish a plurality of beams;
• a direction of arrival estimator (DOAE) coupled to said DBF, said DOAE for determining direction of arrival (DOA) estimates for said plurality of beams;
• a controller coupled to said DBF and to said DOAE;
• means for selecting a first receive subarray of said plurality of elements as a reference array;
• means for selecting a second receive subarray of said plurality of elements;
• means for combining weighted received signals from said second receive subarray and reference array signals from said first receive subarray;
• means for determining a complex baseband signal covariance matrix C for said first receive subarray;
• means for determining a complex cross-correlation vector d using said first receive subarray and said second receive subarray;
• means for determining a complex weight vector w that minimizes received power at said at least one antenna array;
• means for determining a normalized pattern for said at least one antenna array using said complex weight vector w;
• and
• means for determining said direction of arrival estimates using at least one maximum point in said normalized pattern.

A direction of arrival (DOA)-aided digital beamforming (DBF) subsystem comprising:

• at least one antenna array having a plurality of elements;
• a plurality of receive/transmit (Rx/Tx) modules coupled to said plurality of elements;
• a digital beamformer (DBF) coupled to said plurality of Rx/Tx modules, said DBF controlling N elements of said plurality of elements to establish a plurality of beams;
• a direction of arrival estimator (DOAE) coupled to said DBF, said DOAE for determining direction of arrival (DOA) estimates for said plurality of beams;
• a controller coupled to said DBF and to said DOAE;
• means for selecting a first receive subarray of said plurality of elements as a reference array;
• means for selecting a second receive subarray of said plurality of elements;
• means for combining weighted received signals from said second receive subarray and reference array signals from said first receive subarray;
• means for determining a complex baseband signal covariance matrix C for said first receive subarray;
• means for determining a complex cross-correlation vector d using said first receive subarray and said second receive subarray;
• means for determining a complex weight vector w that minimizes received power at said at least one antenna array;
• means for determining a composite pattern for said at least one antenna array using said complex weight vector w;
• and
• means for determining said direction of arrival estimates using at least one minimum point in said composite pattern.