Because the number of transmitted layers can vary dynamically, the number of transmitted demodulation reference signals (DM-RS) can also vary. However, because the network node can know the number of ports, transmitted layers, or the rank, the network node can utilize the number as part of the scheduling information via a downlink or an uplink control channel. Therefore, the DMRS sequence generation can modified such that it depends on the number of ports, transmitted layers, or the rank, thereby generating a different random sequence for different ports.