The present invention relates to a mobile terminal device (401), a base station (400) and a method that make it possible to use a channel quality indicator, CQI, reporting format for CQI reporting from the mobile terminal device to the base station, which CQI reporting format depends on a selected transmit antenna configuration. The mobile terminal device (400) is arranged to receive a signal (404) from a number of transmit antennas, which signal includes a number of subcarriers (412), and to determine the CQI, reporting format for a collection of the subcarriers based on the selected transmit antenna configuration. The mobile terminal device is further arranged to determine a number of CQI values (409) relating to said subcarriers in accordance with the determined CQI reporting format and to transmit the CQI values to the base station in a feedback signal (408). The CQI reporting format is adapted to the selected transmit antenna configuration such that the granularity of CQI reporting depends on the selected transmit antenna configuration.