MIB and SIB in 5G-NR

System information

System Information (SI) is consist of 2 parts-

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

In NR there are two version of SIBs .

  1. One being transmitted periodically same as LTE
  2. Other one is transmitted on demand ,whenever UE requested.

MIB (Master Information Block)

  • MIB transmission will always be on BCH transport channel and PBCH physical channel.
  • Periodicity of MIB will be 80 ms.
  • MIB includes the parameters which are required to acquire SIB1 from cell.
  • The PBCH is transmitted as part of SS/PBCH Block
  • The actual payload of the MIB occupies 23 bits but an additional 1 bit is required to indicate the BCCH message type. Thus the MIB requires a total of 24 bits.
MIB (Master Information Block)  Content
  • System Frame Number :  It provides the 6 Most Significant Bits (MSB) of the current System Frame Number (SFN).
  • Sub Carrier Spacing Common : defines the subcarrier spacing to be used for the reception of SIB I, other broadcast System Information, paging messages and the MSG2 /MSG4 transmitted during initial access.
  • ssb-Subcanier Offset :defines the 4 Least Significant Bits of the subcarrier offset.
  • dmrs-TypeA-Position : It specifies the first symbol used by the Demodulation Reference Signal (DMRS) when using ‘Mapping Type A’. This information element is applicable to the DMRS for both the PDSCH and PUSCH.
  • CellBarred : A UE is not permitted to complete cell selection nor cell reselection onto a cell which is barred so this column is to indicate about cellbarred or not.
  • IntraFreqReselection :  This is applicable when the current cell is lo be treated as barred. a value of ‘allowed’ indicates that the UE is permitted to reselect another cell on the same frequency.

Overall MIB / SIB transmission

MIB and SIB1 are called as β€˜minimum SI’.

System Information Block Type 1 (SIB1)

  • SIB1is transmitted on the DL-SCH.
  • Periodicity of SIB1is 160 ms and repetitive transmission done during 160 ms.
  • Periodic broadcast basis or only on-demand basis of other SIBs is indicated by SIB1.

SIB1 Contents

  • cellSelectionInfo :–It includes the q-RxLevMin , q-RxLevMinOffset , q-RxLevMinSUL , q-QualMin , q-QualMinOffset.
  • CellAccessRelatedInfo :- It includes cell access information for the serving cell .

plmn-IdentityList and cellReservedForOtherUse

  • In PLMN-IdentityInfo it will be having plmn-IdentityList,TAC,RAN-AreaCode(ranac), cellIdentity.
  • ConnEstFailureControl :It is used to configure parameters for connection establishment failure control.
  • SI-SchedulingInfo : Its is needed for acquisition of SI messages. It contains schedulingInfoList((maximum 32) , si-WindowLength, si-RequestConfig, si-RequestConfigSUL, systemIn.formationAreaID.
  • servingCellConfigCommon : ServingCellConfigCommon is used to configure cell specific parameters of a UE’s serving cell in SIB1.
  • ims-EmergencySupport:It indicates about the supportability of IMS emergency bearer services.
  • eCallOverIMS-Support : Indicates whether the cell supports emergency call over IMS services.
  • UE-TimersAndConstants: This contains timers info in all UE states
  • uac-BarringInfo : cell barring based upon Unified Access Barring (UAC).

SIB2 Contents

Cell re-selection information common for intra-frequency, inter-frequency and/ or inter-RAT

SIB3 Contents

Intra frequency cell re-selection information e.g. PCI, q-Offset, q-RxLev, q-Qual, Black cell list.

SIB4 Contents

Inter frequency cell re-selection information e.g. NR-ARFCN.
SIB5 Contents

Inter system cell re-selection toward LTE e.g. EARFCN

SIB6 Contents

Earth quake and Tsunami Warning System primary notifications

SIB7 Contents

Earth quake and Tsunami Warning System secondary notifications

SIB8 Contents

Commercial Mobile Alert services (CMAS) notification

SIB9 Contents

Timing information for UTC, GPS and local time

References :

3GPP TS 38.331 5G; NR; Radio Resource Control (RRC)

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