A method in an arrangement integrated in or attached to a receiver unit in a wireless multi-antenna communication system, said receiver unit equipped to receive data streams sent from one or more transmitter antennas for transmission of data packets from a transmitting unit, the method comprising: receiving an indication from a HARQ-process in case a data packet has been erroneously received; the method further comprising: deriving, after receiving the indication, a metric indicating with what probability it is possible to decode received information content of said data packet from its first transmission and subsequent retransmissions, whereby a calculation of said metric includes an accumulated conditional mutual information of the first transmission and the subsequent retransmissions of said data packet; indicating for a retransmission an antenna at the transmitter site for which the metric provides the closest approximation to a given probability; and providing to the transmitting unit a feedback information element based on said metric, thereby enabling the transmitting unit to determine its resource need for the retransmission of said data packet, whereby the feedback information element contains the derived metric, and whereby the feedback information element is transmitted together with a signaling of acknowledgement messages to the transmitter unit. receiving an indication from a HARQ-process in case a data packet has been erroneously received; the method further comprising: deriving, after receiving the indication, a metric indicating with what probability it is possible to decode received information content of said data packet from its first transmission and subsequent retransmissions, whereby a calculation of said metric includes an accumulated conditional mutual information of the first transmission and the subsequent retransmissions of said data packet; indicating for a retransmission an antenna at the transmitter site for which the metric provides the closest approximation to a given probability; and providing to the transmitting unit a feedback information element based on said metric, thereby enabling the transmitting unit to determine its resource need for the retransmission of said data packet, whereby the feedback information element contains the derived metric, and whereby the feedback information element is transmitted together with a signaling of acknowledgement messages to the transmitter unit. deriving, after receiving the indication, a metric indicating with what probability it is possible to decode received information content of said data packet from its first transmission and subsequent retransmissions, whereby a calculation of said metric includes an accumulated conditional mutual information of the first transmission and the subsequent retransmissions of said data packet; indicating for a retransmission an antenna at the transmitter site for which the metric provides the closest approximation to a given probability; and providing to the transmitting unit a feedback information element based on said metric, thereby enabling the transmitting unit to determine its resource need for the retransmission of said data packet, whereby the feedback information element contains the derived metric, and whereby the feedback information element is transmitted together with a signaling of acknowledgement messages to the transmitter unit.