Systems, methods, and instrumentalities are disclosed for phase noise reference signal (PNRS) transmission, comprising receiving, at a wireless transmit receive unit (WTRU), scheduling information for a Physical Uplink Shared Channel (PUSCH) transmission, wherein the scheduling information includes an indication of a set of physical resource blocks (PRBs) and a modulation coding scheme (MCS) level, determining a density for the PNRS transmission based on at least one of: the MCS level, a frequency band for the PUSCH transmission, or a subcarrier spacing of the PUSCH transmission, and transmitting the PUSCH in the scheduled set of PRBs using the determined density of PNRS.