A measuring device for determining the channel-quality feedback quality of mobile stations contains a base station, a mobile station and a measuring unit. The measuring unit contains at least two antennas and a processing device. The measuring unit and the mobile station receive signals in each case by means of at least two antennas from the same at least two antennas of the base station. The mobile station determines a channel-quality feedback value from the signals it has received. The processing device determines the orthogonality of the signals received by the measuring unit. The processing device determines a channel-quality feedback value from the orthogonality. From this and from the channel-quality feedback value of the mobile station, the processing device determines the quality of the latter.