Technology for a next generation node B (gNB), operable to use phase tracking reference signals (PT-RS) is disclosed. The gNB can identify a modulation and coding 5 scheme (MCS) for the UE for a bandwidth part (BWP) with a subcarrier spacing (SCS). The gNB can select a time density of the PT-RS based on the MCS. The gNB can select a frequency density of the PT-RS based on an allocated bandwidth in the BWP. The gNB can encode the time density and the frequency density, for the PT-RS for transmission to the UE in higher layer signaling.