In the previous chapters we saw how UE uses SSB to get PSS and SSS.
SSB also consists of PBCH block that is used to broadcast System Information
So UE needs to decide PBCH/MIB in order to receive other system information.
In this chapter we shall understand the contents of MIB.
MIB:
->It is transmitted over BCH -> PBCH.
->MIB is transmitted with 80ms periodicity and it is repeated within the 80ms.
-> MIB provides UE with important parameters required to acquire SIB1.
It will also include the information required for monitoring PDCCH for scheduling PDSCH that carries SIB1.
MIB Contents:
Content of the Master Information Block (MIB):
MIB ::= SEQUENCE {
systemFrameNumber
BIT STRING (SIZE (6)),
subCarrierSpacingCommon
ENUMERATED {scs15or60, scs30or120},
ssb-SubcarrierOffset
INTEGER (0..15),
dmrs-TypeA-Position
ENUMERATED {pos2, pos3},
pdcch-ConfigSIB1
PDCCH-ConfigSIB1,
cellBarred
ENUMERATED {barred, notBarred},
intraFreqReselection
ENUMERATED {allowed, notAllowed},
spare BIT STRING (SIZE (1))
}
PDCCH-ConfigSIB1 ::= SEQUENCE {
controlResourceSetZero
ControlResourceSetZero,
searchSpaceZero
SearchSpaceZero
} .
systemFrameNumber: The 6 most significant bits (MSB) of the 10-bit System Frame Number (SFN). The 4 LSB of the SFN are conveyed in the PBCH transport block as part of channel coding (i.e. outside the MIBencoding), as defined in clause 7.1 in TS 38.212 [17].
subCarrierSpacingCommon : Subcarrier spacing for SIB1, Msg.2/4 for initial access and SI-messages. If the UE acquires this MIB on an FR1 carrier frequency, the value scs15or60 corresponds to 15 kHz and the value scs30or120 corresponds to 30 kHz. If the UE acquires this MIB on an FR2 carrier frequency, the value scs15or60 corresponds to 60 kHz and the value scs30or120 corresponds to 120 kHz.
ssb-SubcarrierOffset: Corresponds to kSSB (see TS 38.213 [13]), which is the frequency domain offset between SSB and the overall resource block grid in number of subcarriers.
pdcch-ConfigSIB1: Determines a common ControlResourceSet (CORESET), a common search space space#0 and necessary PDCCH parameters.
controlResourceSetZero: Determines a common ControlResourceSet (CORESET) with ID #0, see TS 38.213 [13], clause 13.
searchSpaceZero: Determines a common search space with ID #0, see TS 38.213 [13], clause 13.
dmrs-TypeA-Position: Position of (first) DM-RS for downlink (see TS 38.211 [16], clause 7.4.1.1.2) and uplink (see TS 38.211 [16], clause 6.4.1.1.3).
cellBarred: Value barred means that the cell is barred, as defined in TS 38.304 [20].
intraFreqReselectionControls: cell selection/reselection to intra-frequency cells when the highest ranked cell is barred, or treated as barred by the UE, as specified in TS 38.304
For PBCH, polar coding and QPSK modulation is used.
TS 38.211, 38.212, 38.213, 38.331, and 38.300
