MIB and SIB reading

Master Information Block on PBCH

The MIB is broadcast on PBCH as part of every SSB transmission and contains just 24 bits of critically important information. Those bits encode the System Frame Number, the subcarrier spacing used for the initial downlink PDCCH, the CORESET zero configuration through the pdcch-ConfigSIB1 field, and the cell barred status indicator. Despite its tiny size, the MIB is the gateway to all other system information because it tells the UE exactly where to find CORESET zero. Once the UE locates CORESET zero it can monitor PDCCH for the DCI that schedules SIB1 on PDSCH.