random sequence is calculated from the following formula: n's as the slot number in the frame and 1 as the OFDM symbol number in the slot. The NS exponent parameter is either 0 or 1. The n°D and n/10 values are provided by the RRC layer via the scramblingID0 and scramblingIDI parameters or take the physical identity number of the PCI cell retrieved at the end of the time synchronization of the mobile as their value. a is the CDM coding group and n2 is 0 or 1. The number of DM-RS symbols and the mapping of DM-RS symbols to RE are statically configured by RRC parameters, or dynamically by DCI control information. The physical DM-RS is present on each RB of the slot where the PDSCH is allocated. In the time domain, two types of mapping are defined: - DM-RS Mapping Type A is based on the slot time interval. The OFDM symbols carrying the DM-RS signals are fixed relative to the start of the slot and are located at position 2 or 3 of the slot; - DM-RS Mapping Type B for which the DM-RS signal is temporally aligned with the PDSCH. 112 NG-RAN and 5G-NR Type A allows the mobile to receive control information on the first symbol, then the DM-RS associated with the PDSCH on symbol 2 or symbol 3, the slot being entirely used to transmit data to the terminal. Type B is used in the case where the PDSCH data is transmitted over a few symbols (mini slot over 2, 4 or 7 symbols). This configuration corresponds to low latency communications. Symbol DM-RS Type A I=3 Type A I=0 Type B Figure 4.10. Three examples of the DM-RS signal and mapping on antenna port 0 The DM-RS is transmitted on one symbol (Single Symbol) or on two consecutive symbols (Double Symbol) per slot depending on the maxlength parameter transmitted by the RRC signaling. At a minimum, one DM-RS symbol per UE is transmitted per slot, but depending on the RRC configuration, additional DM-RS symbols per slot may be added (dmrs-AdditionalPosition) in the time domain. For high speed terminal velocity, the gNB can add three additional DM-RS signals per slot in order to hel