A device for a method for determining the transmission performance of sub-channels of a transmission channel in a radio-communication system is specified, where data-comprising signal carriers are generated for the setup of the transmission channel within the radio-communication system and accommodated in the sub-channels of the transmission channel, and the transmission performance of the sub-channels is determined on the basis of the signal sub-carriers superposed with interferers. In this context, each sub-channel occupies a separate bandwidth sub-range of a total bandwidth range of the transmission channel. The bandwidth sub-range is disposed within the bandwidth at a spacing distance from other bandwidth sub-ranges of the total bandwidth range, and the interferers are limited to the bandwidth sub-range allocated to the respective sub-channel.