A method and apparatus of improving the performance of a mobile radio system (100) comprising at least one radio device (105, 120) having at least two transmission equipments (114) adapted to transmit radio signals within a frequency band is disclosed. The method comprises deriving (220) a relative time delay of the at least two transmission equipments based on at least two sub-band transmit weight vectors, wherein a sub-band transmit weight vector comprises weight vectors applicable to the at least two transmission equipments, respectively, in a sub-band of the frequency band.