Terminology » 5G » 5G MIB and SIB: Master and System Information Blocks Explained

5G MIB and SIB: Master and System Information Blocks Explained

5g mib sib system information nr

This page describes the contents of 5G MIBs (Master Information Blocks) and 5G SIBs (System Information Blocks) and their functions as per the 5G Verizon specification (5G TF). It also mentions MIB and SIB1 contents as per the 5G NR 3GPP standard, as defined in TS V5G.331.

Like LTE, in 5G wireless technology, system information is divided into two main categories:

  • Master Information Block (MIB)
  • System Information Block (SIB)

5G MIB SIB contents

UE applies the system information acquisition procedure to acquire the system information that is broadcasted by the 5G-RAN. The procedure applies to UEs in RRC_IDLE and UEs in RRC_CONNECTED states.

5G MIB Contents | 5G Master Information Block

The 5G Master Information Block (MIB) includes system information transmitted on the xBCH transport channel and the xBCCH logical channel. It uses RLC-SAP Transparent Mode (TM).

5G MIB DescriptionData Type/Size
SystemFrameNumber (SFN)BIT STRING (SIZE (8))
brsTransmissionPeriodENUMERATED {mx5, ms5, ms10, ms20}
Defines the transmission period of the Beam Reference Symbol. Value in number of milliseconds.
Value mx5 corresponds to 5ms repetition when half a subframe is used for xPBCH and BRS transmission.
ms5, ms10, and ms20 correspond to 5ms, 10ms, and 20ms periodicity when complete subframes are used for BRS transmission.
ePBCHTransmissionPeriodENUMERATED {ms0, ms40, ms80, ms160}
Defines the transmission periodicity of ePBCH. ePBCH as defined in V5G.211 Table 6.5.A.4-1.
ms0 defines that ePBCH is not transmitted, and ms40 defines a transmission period of 40ms, and so on.
SpareBIT STRING (SIZE (2))

5G SIB Contents | 5G System Information Block

The IE (Information Element) XSystemInformationBlock contains RRC (radio resource configuration) information, which is common for all UEs. It is transmitted on the xBCCH logical channel and the xBCH transport channel. It uses RLC-SAP Transparent Mode (TM). It is transmitted from the 5G-RAN to the UE. The following table mentions the 5G System Information Block (SIB) contents.

5G SIB DescriptionData Type/Size
plmn-IdentityThe IE PLMN-Identity identifies a Public Land Mobile Network.
Further information regarding how to set the IE is specified in TS 23.003.
It contains MCC, MNC etc.
cellIdentityThe IE CellIdentity is used to unambiguously identify a cell within a PLMN.
Data type/size: BIT STRING (SIZE (28))
cellBarredData type/size: ENUMERATED {barred, notBarred}
cellReservedForOperatorUseData type/size: ENUMERATED {reserved, notReserved}
defaultConfigIDData type/size: INTEGER(0..15)
prach-uRootData type/size: INTEGER (1..70)

Reference: TS V5G.331: “5G Radio Access (5G RA); 5G Radio Resource Control (5G-RRC) protocol specification”

MIB and SIB1 as defined in 3GPP TS 38.331

5G NR system information acquisition

The following figure mentions MIB contents. It is transmitted on BCH with BCCH as a logical channel. It is transmitted from the network (i.e., gNB) to the UE.

5G NR MIB contents

The following figure mentions SIB1 contents. SIB1 contains information that evaluates whether a UE is allowed to access a cell or not. It also defines scheduling-related system information and consists of RRC information common to all UEs.

5G NR SIB1 contents

It is transmitted on logical channels BCCH and BR-BCCH from the network to the UE.

Reference: 3GPP TS 38.331 V15.2.0, RRC protocol specification (Release 15)