 all subcarriers over an OFDM symbol but exhibits low correlation from symbol to symbol. The system configures the PT-RS depending on the quality of the oscillators, carrier frequency, SCS, and modulation and coding schemes that are used for the transmission. The PT-RS for PDSCH is transmitted together with the PDSCH on need basis. The PT-RS is denser in time domain but sparser in frequency domain com- pared to the DM-RS, and if configured, occurs only in conjunction with the DM-RS. UE-specific CSI-RS can be used for estimation of CSI to allow CSI measurement and reporting which assists the gNB in modulation coding scheme (MCS) selection, resource allocation, beamforming, and MIMO rank selection. The CSI-RS can be con- figured for periodic, aperiodic, or semi-persistent transmission with a configurable den- sity by the gNB. The CSI-RS also can be used for interference measurement (IM) and fine frequency/time tracking purposes. Specific instances of CSI-RS can be configured for time/frequency tracking and mobility measurements. In the absence of the cell- specific reference signals in NR the CSI-RS can be used for radio resource manage- ment, measurements and mobility management purposes in connected mode. Tracking reference signals (TRS) are sparse set of reference signals, which are intended to assist the device in time and frequency tracking. The TRS does not exist indepen- dently, and a specific CSI-RS configuration is used as TRS. In addition to time and fre- quency tracking, the TRS is used for estimation of delay spread and Doppler spread at the UE side. It is transmitted with a limited bandwidth for a configurable period of time, controlled by the upper layer parameters. Table 4.1 provides the L1 overhead associated with various NR downlink reference signals. In NR, the overhead due to the L1/L2 control signaling depends on the size and periodicity of the configured control resource set (CORESET) in the cell which includes the overhead from the PDCCH DM-RSs. If the CORESET is transmitted in every slot, max