A method performed by a wireless device, the method comprising: estimating a channel state of a downlink channel; and transmitting a channel state information, CSI, report for the downlink channel based on the channel state, the CSI report indicating a plurality of precoder vectors, wherein each of the precoder vectors corresponds to a frequency sub-band of the bandwidth of the downlink channel, a precoder vector being expressed as a linear combination of spatial-domain components and frequency-domain components, where each of the spatial-domain components is associated with a respective set of one or more frequency-domain components and where the number of frequency-domain components associated with a first spatial-domain component is larger than the number of frequency-domain components associated with a second spatial-domain component, wherein the method further comprises: determining, for each of the spatial-domain components, the number of associated frequency-domain components in the set of one or more frequency-domain components associated with the spatial-domain component; determining linear combination coefficients for each combination of spatial-domain component and associated frequency-domain components; and including an indication of the determined linear combination coefficients as part of the CSI report, wherein, for each spatial-domain component of the spatial-domain components: the CSI report further comprises an indication of the number of frequency-domain components associated with that spatial-domain component; and the indication of the number of frequency-domain components associated with that spatial-domain components is jointly encoded with a selection of the one or more frequency-domain components associated with that spatial-domain component from a set of candidate frequency-domain components. estimating a channel state of a downlink channel; and transmitting a channel state information, CSI, report for the downlink channel based on the channel state, the CSI report indicating a plurality of precoder vectors, wherein each of the precoder vectors corresponds to a frequency sub-band of the bandwidth of the downlink channel, a precoder vector being expressed as a linear combination of spatial-domain components and frequency-domain components, where each of the spatial-domain components is associated with a respective set of one or more frequency-domain components and where the number of frequency-domain components associated with a first spatial-domain component is larger than the number of frequency-domain components associated with a second spatial-domain component, wherein the method further comprises: determining, for each of the spatial-domain components, the number of associated frequency-domain components in the set of one or more frequency-domain components associated with the spatial-domain component; determining linear combination coefficients for each combination of spatial-domain component and associated frequency-domain components; and including an indication of the determined linear combination coefficients as part of the CSI report, wherein, for each spatial-domain component of the spatial-domain components: the CSI report further comprises an indication of the number of frequency-domain components associated with that spatial-domain component; and the indication of the number of frequency-domain components associated with that spatial-domain components is jointly encoded with a selection of the one or more frequency-domain components associated with that spatial-domain component from a set of candidate frequency-domain components. determining, for each of the spatial-domain components, the number of associated frequency-domain components in the set of one or more frequency-domain components associated with the spatial-domain component; determining linear combination coefficients for each combination of spatial-domain component and associated frequency-domain components; and including an indication of the determined linear combination coefficients as part of the CSI report, wherein, for each spatial-domain component of the spatial-domain components: the CSI report further comprises an indication of the number of frequency-domain components associated with that spatial-domain component; and the indication of the number of frequency-domain components associated with that spatial-domain components is jointly encoded with a selection of the one or more frequency-domain components associated with that spatial-domain component from a set of candidate frequency-domain components. the CSI report further comprises an indication of the number of frequency-domain components associated with that spatial-domain component; and the indication of the number of frequency-domain components associated with that spatial-domain components is jointly encoded with a selection of the one or more frequency-domain components associated with that spatial-domain component from a set of candidate frequency-domain components.