For an integer number R (greater than one) of demodulation reference signal DM RS resources that are reserved for SU-MIMO transmissions by a UE, there is associated in a memory a) for a first transmission instance each of the R DM RS resources with a unique one of R spatial layers or R transmit antennas, and b) for a second transmission instance each of the R DM RS resources with a different unique one of the R spatial layers or transmit antennas. The first and second transmission instances (slots or sub-frames) are consecutive. A UE transmission to a network in the first slot/sub-frame comprises each DM RS resource on the respective spatial layer or transmit antenna with which they are associated for the first slot/sub-frame, and a UE transmission to the network in the first slot/sub-frame comprises each DM RS resource on the respective spatial layer or transmit antenna with which they are associated for the second slot/sub-frame.