A method in a transmitter, for transmission of a data channel and a control channel to a receiver, using at least one subframe, and at least one set of reference signals which is selected from a first candidate set of reference signals, or from a second candidate set of reference signals, each set of reference signals comprising a set of antenna ports, wherein the method comprises: assigning resource blocks by means of a control channel for the data channel in the at least one subframe; associating one set of reference signals, selected from the first or the second candidate set of reference signals with the assigned resource blocks, utilising the set of antenna ports of the selected set of reference signals, based on a set of rules related to at least the assigned resource blocks for the data channel; transmitting the control channel; transmitting the data channel on the assigned resource blocks, further comprising determining for each subframe, a set of resource blocks, which is known both to the transmitter and the receiver; and wherein the set of rules related to the assigned resource blocks for the data channel comprises utilising the first candidate set of reference signals when at least one of the following statements is true: all resource blocks assigned for the data channel are within the determined set; or the number of resource blocks comprising resource blocks assigned for the data channel within the determined set exceeds a predetermined threshold value; or the lowest indexed resource block of the assigned resource blocks is within the determined set; or the largest indexed resource block of the assigned resource blocks is within the determined set; and otherwise utilising the second candidate set of reference signals; wherein the first candidate set of reference signals comprises cell specific reference signals or receiver specific reference signals, and wherein the second candidate set of reference signals comprises receiver specific reference signals. assigning resource blocks by means of a control channel for the data channel in the at least one subframe; associating one set of reference signals, selected from the first or the second candidate set of reference signals with the assigned resource blocks, utilising the set of antenna ports of the selected set of reference signals, based on a set of rules related to at least the assigned resource blocks for the data channel; transmitting the control channel; transmitting the data channel on the assigned resource blocks, further comprising determining for each subframe, a set of resource blocks, which is known both to the transmitter and the receiver; and wherein the set of rules related to the assigned resource blocks for the data channel comprises utilising the first candidate set of reference signals when at least one of the following statements is true: all resource blocks assigned for the data channel are within the determined set; or the number of resource blocks comprising resource blocks assigned for the data channel within the determined set exceeds a predetermined threshold value; or the lowest indexed resource block of the assigned resource blocks is within the determined set; or the largest indexed resource block of the assigned resource blocks is within the determined set; and otherwise utilising the second candidate set of reference signals; all resource blocks assigned for the data channel are within the determined set; or the number of resource blocks comprising resource blocks assigned for the data channel within the determined set exceeds a predetermined threshold value; or the lowest indexed resource block of the assigned resource blocks is within the determined set; or the largest indexed resource block of the assigned resource blocks is within the determined set; and otherwise utilising the second candidate set of reference signals; wherein the first candidate set of reference signals comprises cell specific reference signals or receiver specific reference signals, and wherein the second candidate set of reference signals comprises receiver specific reference signals.