The invention relates to a data transmission method and a radio system comprising at least one subscriber terminal and at least one base station including an antenna, by means of which the base station transmits signals to the subscriber terminal. The subscriber terminal includes a measuring mechanism which determines the quality of the signals received by the subscriber terminal by comparing the received signals with at least one signal quality threshold level. When only one signal exceeds the threshold, the subscriber terminal sends to the base station, which transmitted the signal that exceeded the threshold, a command to use, when transmitting a signal to the subscriber terminal, the antenna with which the signal that exceeded the threshold was transmitted, or the transmission direction to which the signal that exceeded the threshold was transmitted.