A pre-coding method is disclosed of a multi-user, multi-antenna transmitter configured for transmission of respective signals to a plurality of users. The method comprises determining (for each pair of users of the plurality) a spatial correlation value for the pair of users, and determining a first correlation threshold value based on the number of users of the plurality. The method also comprises determining whether or not one or more pairs of users has a spatial correlation value that falls on or above the first correlation threshold value. When one or more pairs of users has a spatial correlation value that falls on or above the first correlation threshold value, the method comprises discarding one user comprised in at least one of the one or more pairs to provide a reduced plurality of users, and updating the first correlation threshold value based on the number of users of the reduced plurality. The discarding and updating steps are repeated until none of the spatial correlation values falls on or above the updated first correlation threshold value. Then, the method comprises generating the respective signals for transmission to the users of the reduced plurality by application of pre-coding. Corresponding apparatus, transmitter, base station and computer program product are also disclosed.