eceived signal and for beamforming. The DM-RS physical signal is associated with a physical channel. The physical PT-RS (Phase Tracking Reference Signal) is a reference signal to compensate the frequency difference between the transmitter and receiver and suppress phase noise. The physical PRS (Positioning Reference Signal) is used by the mobile to determine its location from the OTDOA (Observed Time Difference of Arrival) mechanism. The physical RIM (Remote Interference Management) signal is used to provide information about interference experienced by other gNB radio nodes, in order to control the DL/UL interference. 4.4.2. Physical channels 4.4.2.1. Downlink direction The physical PBCH (Physical Broadcast Channel) transmits the BCH transport channel containing system information corresponding to the MIB (Master Information Block) message. The PBCH channel is time multiplexed with the PSS and SSS channels to form the SSB (Synchronization Signal Block). The physical PDCCH (Physical Downlink Control Channel) transmits the DCI control information, which allows us to define: - the allocation of resources, as well as the modulation and coding scheme, for the data contained in the PDSCH (Physical Downlink Shared Channel) and PUSCH (Physical Uplink Shared Channel) physical channels; - the transmitting power of the PUCCH (Physical Uplink Control Channel) and PUSCH physical channels. The PDSCH physical channel transmits the DL-SCH (Downlink Shared Channel) and PCH (Paging Channel) transport channels. 5G-NR Radio Interface - The Physical Layer The Physical Multicast Channel (PMCH) transmits the MCH transport channel for MBSFN transmissions. 4.4.2.2. Uplink direction The PRACH (Physical Random Access Channel) contains a preamble used by the mobile to ask for the establishment of a radio bearer. The random access procedure is the first step in connecting the mobile to the gNB radio node (see Chapter 3). The PUCCH (Physical Uplink Control Channel) allows the UE terminal to send UCI (Uplink Control Information) to the gNB ra