Over-the-air beamforming calibration

A non-transitory computer readable medium, having thereon a computer program comprising program instructions, the computer program being loadable into a data processing unit and configured to cause execution of a method when the computer program is run by the data processing unit, wherein the method is for over-the-air beamforming calibration for a multi-antenna transceiver having a first plurality of antenna elements connected to respective transceiver chains, wherein beamforming calibration comprises determining respective beamforming calibration factors for the transceiver chains of the antenna elements of the first plurality, and wherein the method comprises:

• determining a second plurality of measurement resources for calibration sounding, wherein the second plurality is smaller than the first plurality;
• for each measurement resource of the second plurality, selecting one or more antenna elements of the first plurality for sounding signal transmission, wherein each antenna element of the first plurality is selected for one or more of the measurement resources of the second plurality;
• and
• using each measurement resource of the second plurality, overlappingly transmitting respective sounding signals by the selected one or more antenna elements.

An apparatus for over-the-air beamforming calibration of a multi-antenna transceiver having a first plurality of antenna elements connected to respective transceiver chains, wherein beamforming calibration comprises determining respective beamforming calibration factors for the transceiver chains of the antenna elements of the first plurality, the apparatus comprising controlling circuitry configured to cause:

• determination of a second plurality of measurement resources for calibration sounding, wherein the second plurality is smaller than the first plurality;
• for each measurement resource of the second plurality, selection of one or more antenna elements of the first plurality for sounding signal transmission, wherein each antenna element of the first plurality is selected for one of the measurement resources of the second plurality;
• and
• using each measurement resource of the second plurality, overlapping transmission of respective sounding signals by the selected one or more antenna elements.