A computer - implemented method performed by an access node, the method comprising: • sending (step 305) a configuration of one or more channel state information reference signal, CSI-RS, resources and a configuration of one or more sounding reference signal, SRS, resources to a user equipment, UE, the configuration of the one or more CSI-RS resources and the configuration of the one or more SRS resources including at least time-frequency resources; • generating first control information including an identifier of a SRS resource set that includes the one or more SRS resources, the one or more SRS resources to be used by the UE to send at least one precoded SRS, wherein the at least one precoded SRS is precoded by one or more candidate precoders to the access node; • generating second control information including an identifier of a CSI-RS resource among the one or more CSI-RS resources, wherein the CSI-RS resource among the one or more CSI-RS resources conveys a CSI-RS to be used at the UE to perform measurements, and wherein the one or more candidate precoders are to be determined at the UE in accordance with the measurements of the CSI-RS; • generating (step 705) an association between the identifier of the SRS resource set and the identifier of the CSI-RS resource; • sending (steps 307, 709) a SRS request field in a SRS request to the UE, the SRS request field is used to indicate the SRS resource set and the CSI-RS resource associated to the SRS resource set by the generated association, wherein the indication of the SRS resource set and the associated CSI-RS resource by using the SRS request field means that the one or more candidate precoders used for SRS transmission in the one or more SRS resources within the SRS resource set are derived in accordance with the measurements of the CSI-RS conveyed on the CSI-RS resource; • sending (step 309) the CSI-RS on the CSI-RS resource to the UE, the CSI-RS being sent in accordance with the configuration of the CSI-RS resource; • receiving (step 311) at least one SRS precoded by the one or more candidate precoders in the one or more SRS resources from the UE. • sending (step 305) a configuration of one or more channel state information reference signal, CSI-RS, resources and a configuration of one or more sounding reference signal, SRS, resources to a user equipment, UE, the configuration of the one or more CSI-RS resources and the configuration of the one or more SRS resources including at least time-frequency resources; • generating first control information including an identifier of a SRS resource set that includes the one or more SRS resources, the one or more SRS resources to be used by the UE to send at least one precoded SRS, wherein the at least one precoded SRS is precoded by one or more candidate precoders to the access node; • generating second control information including an identifier of a CSI-RS resource among the one or more CSI-RS resources, wherein the CSI-RS resource among the one or more CSI-RS resources conveys a CSI-RS to be used at the UE to perform measurements, and wherein the one or more candidate precoders are to be determined at the UE in accordance with the measurements of the CSI-RS; • generating (step 705) an association between the identifier of the SRS resource set and the identifier of the CSI-RS resource; • sending (steps 307, 709) a SRS request field in a SRS request to the UE, the SRS request field is used to indicate the SRS resource set and the CSI-RS resource associated to the SRS resource set by the generated association, wherein the indication of the SRS resource set and the associated CSI-RS resource by using the SRS request field means that the one or more candidate precoders used for SRS transmission in the one or more SRS resources within the SRS resource set are derived in accordance with the measurements of the CSI-RS conveyed on the CSI-RS resource; • sending (step 309) the CSI-RS on the CSI-RS resource to the UE, the CSI-RS being sent in accordance with the configuration of the CSI-RS resource; • receiving (step 311) at least one SRS precoded by the one or more candidate precoders in the one or more SRS resources from the UE.