What is the size of PBCH payload in NR? Is this a fixed size?

Question

Anyhow PHY is appending 4bits of SFN with MIB payload, but As per RRC MIB payload it is not part of it. Why is this two type of MIB payload?

Answer 1

Hi Bharath,

If you look ASN struture of MIB below you can understand.

BCCH-BCH-Message ::= SEQUENCE {
message BCCH-BCH-MessageType
}
BCCH-BCH-MessageType ::= CHOICE {
mib MIB,
messageClassExtension SEQUENCE {}
}
As you see here, BCCH-BCH is made of one choice parameter which has two elements (MIB or messageClassExtension). So this choice parameter requires 1 bit.BCCH-BCH bit length can be one of the followings :

i) bit length of BCCH-BCH = bit length of mib + 1

ii) bit length of BCCH-BCH = messageClassExtension + 1

Typically MIB is 23 Bit.