Methods, apparatus and computer programs for controlling feedback about channel conditions

Abstract

A user equipment (UE) provides feedback about channel conditions. From a set of primary sub-bands subject to channel state information reporting by the UE, there is identified one or more of the primary sub-bands for reporting channel quality with a finer frequency-domain granularity than other primary sub-bands of the set (). The one or more is less than all primary sub-bands in the set. In various embodiments, either the UE or the network can select which are the primary sub-bands to be identified for the finer granularity reporting, and the selection can be for example the best primary sub-bands or those with the highest variance in a measure of channel quality or random (). Then for each of the identified primary sub-bands, the UE measures and reports the channel quality with the finer frequency-domain granularity for each secondary sub-band whose frequency lay within the respective identified primary sub-band.