Methods and wireless devices for estimating antenna calibration error in a wireless communication network

A method performed by a transmitter of a wireless communication network (100), for estimating antenna calibration error in the transmitter, the transmitter comprising a plurality of radio antennas arranged in a known geometrical configuration, the method comprising:

• obtaining (302) channel data of a communication channel between the transmitter and a receiver based on channel data fed back wirelessly by the receiver to the transmitter, the channel data feedback by the receiver being based on one or more Reference Signals, RS, sent from the transmitter to the receiver, the obtained (302) channel data comprising HOTA and HTX, HOTA being the channel data contributed by a wireless propagation path between the transmitter and the receiver, HTX being the channel data contributed by the antenna calibration error of the transmitter;
• determining (306) a direction between the receiver and the transmitter in relation to the known geometrical configuration arrangement of the plurality of radio antennas of the transmitter, based on the obtained (302) channel data, by applying a subspace method;
• wherein the determined (306) direction is indicating HOTA;
• mitigating (308) the HOTA from the obtained (302) channel data by the determined (306) direction by rotating the direction between the transmitter and the receiver to a common direction;
• providing (310) the HTX part of the obtained (302) channel data after the HOTA being mitigated (308).

A receiver operable in a wireless communication network (100) and configured for estimating antenna calibration error in the receiver, the receiver comprising a plurality of radio antennas arranged in a known geometrical configuration, the receiver comprising a processing circuitry (603) and a memory (604), said memory (603) containing instructions executable by said processing circuitry (603), whereby receiver is operative for:

• obtaining channel data of a communication channel between a transmitter and the receiver based on one or more Reference Signals, RS, sent wirelessly between the transmitter and the plurality of antennas of the receiver, the obtained channel data comprising HOTA and HRX, HOTA being the channel data contributed by a wireless propagation path between the transmitter and the receiver, HRX being the channel data contributed by the antenna calibration error of the receiver;
• determining a direction between the transmitter and the receiver in relation to the known geometrical configuration arrangement of the plurality of radio antennas of the receiver, based on the obtained channel data, by applying a subspace method;
• wherein the determined direction is indicating the HOTA;
• mitigating the HOTA from the obtained channel data based on the determined direction by rotating the direction between the transmitter and the receiver to a common direction;
• providing the HRX part of the obtained channel data after the HOTA being mitigated.

A transmitter operable in a wireless communication network (100) and configured for estimating antenna calibration error in the transmitter, the transmitter comprising a plurality of radio antennas arranged in a known geometrical configuration, the transmitter comprising a processing circuitry (703) and a memory (704), said memory (703) containing instructions executable by said processing circuitry (703), whereby transmitter is operative for:

• obtaining channel data of a communication channel between the transmitter and a receiver based on channel data fed back wirelessly by the receiver to the transmitter, the channel data feedback by the receiver being based on one or more Reference Signals, RS, sent from the transmitter to the receiver, the obtained channel data comprising HOTA and HTX, HOTAbeing the channel data contributed by a wireless propagation path between the transmitter and the receiver, HTX being the channel data contributed by the antenna calibration error of the transmitter;
• determining a direction between the receiver and the transmitter in relation to the known geometrical configuration arrangement of the plurality of radio antennas of the transmitter, based on the obtained channel data, by applying a subspace method;
• wherein the determined direction is indicating HOTA;
• mitigating the HOTA from the obtained channel data by the determined direction by rotating the direction between the transmitter and the receiver to a common direction;
• providing the HTX part of the obtained channel data after the HOTA being mitigated.