A method in a network node of a wireless communication network, the network node operable to separately schedule radio transmissions per sub-subframe, SSF, wherein an SSF comprises a subset of resource elements in a sub frame, the method comprising: mapping a first demodulation reference signal, DMRS, to one or more first resource elements in a first SSF, the one or more first resource elements associated with a first set of one or more antenna ports; mapping a second DMRS to one or more second resource elements in a second SSF, the one or more second resource elements associated with the first set of one or more antenna ports, and a precoding of the second DMRS differs from a precoding of the first DMRS; scheduling a first physical downlink shared channel, PDSCH, transmission during the first SSF precoded in accordance with the first DMRS; scheduling a second PDSCH transmission during the second SSF precoded in accordance with the second DMRS; and transmitting the scheduled first and second PDSCH transmissions; the method further comprising: mapping a third DMRS to one or more third resource elements in the first SSF, the one or more third resource elements associated with a second set of one or more antenna ports; mapping a fourth DMRS to one or more fourth resource elements in the second SSF, the one or more fourth resource elements associated with the second set of one or more antenna ports; scheduling a third PDSCH transmission during a third SSF precoded in accordance with the third DMRS; scheduling a fourth PDSCH transmission during a fourth SSF precoded in accordance with the fourth DMRS; and transmitting the scheduled third and fourth PDSCH transmissions. mapping a first demodulation reference signal, DMRS, to one or more first resource elements in a first SSF, the one or more first resource elements associated with a first set of one or more antenna ports; mapping a second DMRS to one or more second resource elements in a second SSF, the one or more second resource elements associated with the first set of one or more antenna ports, and a precoding of the second DMRS differs from a precoding of the first DMRS; scheduling a first physical downlink shared channel, PDSCH, transmission during the first SSF precoded in accordance with the first DMRS; scheduling a second PDSCH transmission during the second SSF precoded in accordance with the second DMRS; and transmitting the scheduled first and second PDSCH transmissions; the method further comprising: mapping a third DMRS to one or more third resource elements in the first SSF, the one or more third resource elements associated with a second set of one or more antenna ports; mapping a fourth DMRS to one or more fourth resource elements in the second SSF, the one or more fourth resource elements associated with the second set of one or more antenna ports; scheduling a third PDSCH transmission during a third SSF precoded in accordance with the third DMRS; scheduling a fourth PDSCH transmission during a fourth SSF precoded in accordance with the fourth DMRS; and transmitting the scheduled third and fourth PDSCH transmissions. mapping a third DMRS to one or more third resource elements in the first SSF, the one or more third resource elements associated with a second set of one or more antenna ports; mapping a fourth DMRS to one or more fourth resource elements in the second SSF, the one or more fourth resource elements associated with the second set of one or more antenna ports; scheduling a third PDSCH transmission during a third SSF precoded in accordance with the third DMRS; scheduling a fourth PDSCH transmission during a fourth SSF precoded in accordance with the fourth DMRS; and transmitting the scheduled third and fourth PDSCH transmissions.