System Information (SI) is consisting of 2 parts-
- MIB (Master Information Block)
- SIBs (System Information Block)
In NR there are two version of SIBs .
- One being transmitted periodically same as LTE
- 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.
- 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 ‘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.
- cellSelectionInfo :–It includes the q-RxLevMin , q-RxLevMinOffset , q-RxLevMinSUL , q-QualMin , q-QualMinOffset.
- CellAccessRelatedInfo :- It includes cell access information for the serving cell .
- 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).
Cell re-selection information common for intra-frequency, inter-frequency and/ or inter-RAT
Intra frequency cell re-selection information e.g. PCI, q-Offset, q-RxLev, q-Qual, Black cell list.
Inter frequency cell re-selection information e.g. NR-ARFCN.
Inter system cell re-selection toward LTE e.g. EARFCN
Earthquake and Tsunami Warning System primary notifications
Earthquake and Tsunami Warning System secondary notifications
Commercial Mobile Alert services (CMAS) notification
Timing information for UTC, GPS and local time
3GPP TS 38.331 5G; NR; Radio Resource Control (RRC)