3GPP 38.300 v19.3.0 — the document's own text
5.2.5.5 Reception of SIB1
Taught in 2. The six working groups and the line between them (TSG RAN — the group that specifies the radio, overview), 2. The six groups, and what each one worries about (TSG RAN — the group that specifies the radio, quick start).
The Master Information Block (MIB) on PBCH provides the UE with parameters (e.g. CORESET#0 configuration) for monitoring of PDCCH for scheduling PDSCH that carries the System Information Block 1 (SIB1). PBCH may also indicate that there is no associated SIB1, in which case the UE may be pointed to another frequency from where to search for an SSB that is associated with a SIB1 as well as a frequency range where the UE may assume no SSB associated with SIB1 is present. The indicated frequency range is confined within a contiguous spectrum allocation of the same operator in which SSB is detected. MIB on PBCH may also indicate that SIB1 is not being broadcast, in which case the UE may transmit OD-SIB1 request if it has a valid OD-SIB1 request configuration for this cell as described in 15.4.2.9.