System Information (SI) consists of a MIB and a number of SIBs, which are divided into Minimum SI and Other SI:

• Minimum SI comprises basic information required for initial access and information for acquiring any other SI. Minimum SI consists of:
  • MIB contains cell barred status information and essential physical layer information of the cell required to receive further system information, e.g. CORESET#0 configuration. MIB is periodically broadcast on BCH.
  • SIB1 defines the scheduling of other system information blocks and contains information required for initial access. SIB1 is also referred to as Remaining Minimum SI (RMSI) and is periodically broadcast on DL-SCH or sent in a dedicated manner on DL-SCH to UEs in RRC_CONNECTED.
• Other SI encompasses all SIBs not broadcast in the Minimum SI. Those SIBs can either be periodically broadcast on DL-SCH, broadcast on-demand on DL-SCH (i.e. upon request from UEs in RRC_IDLE, RRC_INACTIVE, or RRC_CONNECTED), or sent in a dedicated manner on DL-SCH to UEs in RRC_CONNECTED (i.e., upon request, if configured by the network, from UEs in RRC_CONNECTED or when the UE has an active BWP with no common search space configured or when the UE configured with inter cell beam management is receiving DL-SCH from a TRP with PCI different from serving cell's PCI). Other SI consists of:
  • SIB2 contains cell re-selection information, mainly related to the serving cell;
  • SIB3 contains information about the serving frequency and intra-frequency neighbouring cells relevant for cell re-selection (including cell re-selection parameters common for a frequency as well as cell specific re-selection parameters);
  • SIB4 contains information about other NR frequencies and inter-frequency neighbouring cells relevant for cell re-selection (including cell re-selection parameters common for a frequency as well as cell specific re-selection parameters), which can also be used for NR idle/inactive measurements;
  • SIB5 contains information about E-UTRA frequencies and E-UTRA neighbouring cells relevant for cell re-selection (including cell re-selection parameters common for a frequency as well as cell specific re-selection parameters);
  • SIB6 contains an ETWS primary notification;
  • SIB7 contains an ETWS secondary notification;
  • SIB8 contains a CMAS warning notification;
  • SIB9 contains information related to GPS time and Coordinated Universal Time (UTC);
  • SIB10 contains the Human-Readable Network Names (HRNN) of the NPNs listed in SIB1;
  • SIB11 contains information related to idle/inactive measurements;
  • SIB15 contains information related to disaster roaming;
  • SIB16 contains slice-based cell reselection information;
  • SIB17 and SIB17bis contain information related to TRS configuration for UEs in RRC_IDLE/RRC_INACTIVE;
  • SIBpos contains positioning assistance data as defined in TS 37.355 and TS 38.331;
  • SIB18 contains information related to the Group IDs for Network selection (GINs) associated with SNPNs listed in SIB1.
  • SIB19 in TN contains NTN-specific parameters for NTN neighbour cells as defined in TS 38.331.

For sidelink, Other SI also includes:

• SIB12 contains information related to NR sidelink communication;
• SIB13 contains information related to SystemInformationBlockType21 for V2X sidelink communication as specified in clause 5.2.2.28 of TS 36.331;
• SIB14 contains information related to SystemInformationBlockType26 for V2X sidelink communication as specified in clause 5.2.2.33 of TS 36.331;
• SIB23 contains information related to ranging and sidelink positioning;
• SIB25 contains TN coverage are information as defined in TS 38.331.

For non-terrestrial network, Other SI also includes:

• SIB19 contains NTN-specific parameters for serving cell and optionally NTN-specific parameters for neighbour cells as defined in TS 38.331.

For MBS broadcast, Other SI also includes:

• SIB20 contains MCCH configuration;
• SIB21 contains information related to service continuity for MBS broadcast reception.

For MBS multicast reception in RRC_INACTIVE state, Other SI also includes:

• SIB24 contains the information required to acquire the multicast MCCH/MTCH configuration as defined in TS 38.331.

For ATG network, Other SI also includes:

• SIB22 contains ATG-specific parameters for serving cell and optionally ATG-specific parameters for neighbour cells as defined in TS 38.331.

Figure 7.3.1-1 below summarises System Information provisioning.

For a cell/frequency that is considered for camping by the UE, the UE is not required to acquire the contents of the minimum SI of that cell/frequency from another cell/frequency layer. This does not preclude the case that the UE applies stored SI from previously visited cell(s). If the UE cannot determine the full contents of the minimum SI of a cell by receiving from that cell, the UE shall consider that cell as barred. In case of BA, the UE only acquires SI on the active BWP. If the UE is configured with inter cell beam management:

• the UE is not required to acquire the SI from the serving cell while it is receiving DL-SCH from a TRP with PCI different from serving cell's PCI.

The MIB is mapped on the BCCH and carried on BCH while all other SI messages are mapped on the BCCH, where they are dynamically carried on DL-SCH. The scheduling of SI messages part of Other SI is indicated by SIB1. For UEs in RRC_IDLE and RRC_INACTIVE while SDT procedure is not ongoing (see clause 18), a request for Other SI triggers a random access procedure (see clause 9.2.6) where MSG3 includes the SI request message unless the requested SI is associated to a subset of the PRACH resources, in which case MSG1 is used for indication of the requested Other SI. When MSG1 is used, the minimum granularity of the request is one SI message (i.e. a set of SIBs), one RACH preamble and/or PRACH resource can be used to request multiple SI messages and the gNB acknowledges the request in MSG2. When MSG 3 is used, the gNB acknowledges the request in MSG4. For UEs in RRC_CONNECTED, a request for Other SI may be sent to the network, if configured by the network, in a dedicated manner (i.e., via UL-DCCH) and the granularity of the request is one SIB. The gNB may respond with an RRCReconfiguration including the requested SIB(s). It is a network choice to decide which requested SIBs are delivered in a dedicated or broadcasted manner. The Other SI may be broadcast at a configurable periodicity and for a certain duration. The Other SI may also be broadcast when it is requested by UE in RRC_IDLE/RRC_INACTIVE/RRC_CONNECTED. For a UE to be allowed to camp on a cell it must have acquired the contents of the Minimum SI from that cell. There may be cells in the system that do not broadcast the Minimum SI and where the UE therefore cannot camp.

Change of system information (other than for ETWS/CMAS, see clause 16.4) only occurs at specific radio frames, i.e. the concept of a modification period is used. System information may be transmitted a number of times with the same content within a modification period, as defined by its scheduling. The modification period is configured by system information. When the network changes (some of the) system information, it first notifies the UEs about this change, i.e. this may be done throughout a modification period. In the next modification period, the network transmits the updated system information. Upon receiving a change notification, the UE acquires the new system information from the start of the next modification period. The UE applies the previously acquired system information until the UE acquires the new system information.