The invention relates to a method in a base station serving a cell, the base station using a frequency bandwidth and comprising an antenna arrangement and a controller. The antenna arrangement comprises a number of antenna devices and a beamformer. The method comprises the steps of: associating, in the beamformer, at least a first and a second frequency band with a respective first and a second beam, each frequency band comprising a part of the frequency bandwidth used by the base station; dynamically determining, in the controller, a degree of utilization of the at least first and second frequency bands within the at least first and second beam; and re-associating, in the beamformer, the at least first and second frequency bands with the first and second beam, based on the determined degree of utilization of frequency bands. The invention also relates to base stations, computer programs and computer program products.