NG-RAN and 5G-NR

95G-NR Radio Interface – Radio Access Procedure

9.1. System information

System information broadcasts radio characteristics of the cell, radio characteristics of neighboring cells and alerts.

System information consists of a Master Information Block (MIB) message and a series of System Information Block (SIB) messages.

The MIB and SIB1 constitute the minimum information for the mobile. SIB1 carries RMSI (Remaining Minimal System Information).

Table 9.1 provides the characteristics of the MIB message support and SIB messages.

Table 9.1. Support of message relating to system information

SRB	RLC mode	Logical channel	Transport channel	Physical channel
No object	TM	BCCH	BCH	PBCH
Master Information Block
No object	TM	BCCH	DL-SCH	PDSCH
System Information Block

The BCCH logical channel transports MIB information on 24 bits.

The PBCH physical channel adds an additional 8 bits of payload (PBCH Payload).

Generation of the PBCH data is therefore composed of a 24-bit block from the BCH channel, then 8 bits and the 24-bit CRC code (Figure 9.1).

The payload of the PBCH contains:

1. – 4 least significant bits completing the frame number transmitted in the MIB message;
2. – 3 bits for (depending on the number of SSB (synchronization signal block) bursts):
   1. - the index of the synchronization signal block (SSB Index) for beam sweeping of 64 bursts (FR2),
   2. - or 1 most significant bit for the offset of the SSB block (K_ssb) and 2 bits not used in the specification of Release 16;
3. – 1 bit ...