According to the invention, a base station has an antenna device with a plurality of antenna elements and is connected to a subscriber station via a radio interface. The direction of incidence, the attenuation and the delay times of connection paths used for beam forming for signal sections for channel estimation purposes are determined from the transmissions of the other radio station in a known manner. The beam-forming vector for the transmit signal is constant during these signal sections for channel estimation purposes, for which the radio station can estimate a reception characteristic of the other radio station. Outside the signal sections for channel estimation, a symbol-specific beam-forming vector is determined which takes into account variable symbol-related properties of the transmit signal (for example correlation properties of CDMA codes) which are not constant during a time slot but rather vary from symbol to symbol.