periodic CSI-RS resources in two consecutive slots with two periodic CSI-RS resources in each slot. The periodic CSI-RS resources in the CSI-RS resource set configured with RRC parameter trs-Info have the same periodicity, bandwidth and subcarrier location. The time-domain location of the TRS is determined by two periodic CSI-RS resources in a slot, or four periodic CSI-RS resources in two consecutive slots and via RRC signaling. The density of the TRS in one physical resource block is three REs per symbol. The TRS can be time-division multiplexed with the synchronization signal/PBCH block (SSB). 4.1.3 Control Channels 4.1.3.1 Physical Broadcast Channel In order to select a PLMN and camp on a cell, a UE must perform a cell search in the sup- ported frequency bands. The procedure requires the UE to achieve time and frequency synchronization with a specific cell. This enables decoding of PBCH which carries the MIB containing the critical system information necessary to decode transmissions on PDSCH. In NR, the SI is divided into minimum SI and other SI. The minimum SI is peri- odically broadcast and comprises basic information required for initial access and New Radio Access Physical Layer Aspects (Part 2) 433 Minimum system information (MIB+RMSI) always present and broadcast periodically Other system information (OSI) optionally present and broadcast periodically System information request On-demand other system information broadcast or dedicated signaling Figure 4.8 Transmission of system information in NR [11]. information for acquiring other SI broadcast periodically or scheduled on-demand. The other SI encompasses everything else not broadcast in the minimum SI message and may be either broadcast or individually transmitted to the UE. In the latter case, the on- demand transmission of other SI can be triggered by the network or based on a request from the UE. The change of SI can only occur at specific radio frames. Note that to ensure coverage and reliability, the SI may be transmitted a number of times with 