NG-RAN and 5G-NR: 5G Radio Access Network and Radio Interface, First Edition. Frédéric Launay. C ISTE Ltd 2021. Published by ISTE Ltd and John Wiley & Sons, Inc. 192 NG-RAN and 5G-NR A BWP in a resource grid can overlap. The bandwidth part is defined by: - a frequency band corresponding to a number of PRBs (Physical Resource Block); - a numerology characterizing the bandwidth of the PRB block and the cyclic prefix (normal or extended); - a starting position calculated by the number of common resource block CRB (Common Resource Block) which separates the BWP band from the reference point A of the 5G-NR carrier. The initial BWP corresponds to a 5G-NR sub-band on which the mobile UE (User Equipment): - searches for the SSB (Synchronization Signal Block) (see Chapter 6); - listens to paging notifications sent to the common search space and to specific control information sent to the dedicated search space; - issues the random access request for the establishment of the radio connection. The size of the BWP depends on the number of PRBs and the numerology. In the standby state, the bandwidth of the BWP is reduced to minimize the power consumption of the UE mobile. In the connected state: - the mobile is configured with a BWP active in both directions of transmission (UL: UpLink and DL: DownLink); - the size of the BWPs can be equal to the maximum of the bandwidth of the 5G carrier; - multiple BWPs can be aggregated; however, there can only be one active BWP per 5G carrier (one active BWP on the main PCell cell, and one active BWP on each secondary SCell cell). The BWP makes it possible to adapt to the maximum bandwidth of the terminal, for example IoT (Internet of Things) terminals. In the standby state, the mobile camps on a cell which broadcasts the SSB block and the SIB1 (System Information Block Type 1) information allowing the mobile to find the configuration of the initial BWP partition. 5G-NR Radio Interface - Bandwidth Part The configuration of the initial BWP is contained in the Minimum System Information (MS