A base station and a method of operating a base station

The invention relates to a base station (100) configured to communicate with at least one user equipment (105a-g). The base station (100) comprises: an antenna array (101a) with a plurality of antennas configured to establish a duplex communication channel with the at least one user equipment (105a-g), wherein the duplex communication channel is associated with a correlation matrix pair comprising a downlink correlation matrix Ri describing the channel state in the downlink direction and an uplink correlation matrix Ri UL describing the channel state in the uplink direction; and a processor (103) configured to in a training phase, generate for a plurality of positions of the at least one user equipment (105a-g) or a plurality of times a plurality of correlation matrix pairs (Ri, Ri UL), wherein the processor (103) is configured to determine each uplink correlation matrix Ri UL of the plurality of correlation matrix pairs (Ri, Ri UL) on the basis of a respective uplink training signal received from the at least one user equipment (105a-g) and to associate each uplink correlation matrix Ri UL with a corresponding downlink correlation matrix Ri; and in an exploitation phase, determine a further uplink correlation matrix Rj UL on the basis of a further uplink training signal received from the at least one user equipment (105a-g) and estimate a further downlink correlation matrix Rj corresponding to the further uplink correlation matrix Rj UL on the basis of the further uplink correlation matrix Rj UL and the plurality of correlation matrix pairs (Ri, Ri UL).