5G NR : System Information

In 5G NR, the system information is consist of MIB and the number of SIBs, which is divided into two groups i.e. Minimum System Information (MSI) and other system information (OSI)

Minimum SI ( MSI )

  • 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.
  • 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 (Transport Channel) or sent in a dedicated manner on DL-SCH(Transport Channel) to UEs in RRC_CONNECTED .
  • SIBs are mapped from BCCH to DLSCH and DLSCH to PDSCH channels.

Other SI ( OSI )

  • All SIBs are not broadcast in the MSI.
  • 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 or RRC_INACTIVE), or
  • sent in a dedicated manner on DL-SCH to UEs in RRC_CONNECTED.
  • Other SI consists of SIB2, SIB3, SIB4, SIB5, SIB6, SIB7, SIB8, SIB9.

MIB

  • MIB stands for Master Information Block
  • MIB is always mapped on BCCH (Logical channel) and carried on BCH (Transport channel), then BCH( Transport channel) is mapped on PBCH (Physical channel)
  • The MIB is transmitted with the periodicity of 80 ms & Repetition made with 80 ms
  • MIB includes parameters that are needed to acquire SIB1 from the cell
  • Repetitions are scheduled to the period of SSB
  • The size of MIB is 24-bit information

SIB1

  • SIB1 stands for System Information Block 1
  • SIB1 contains information relevant when evaluating –
    • if a UE is allowed to access a cell and defines the scheduling of other system information.
    • It also contains radio resource configuration information that is common for all UEs
    • The barring information applied to the unified access control.
  • SIB1 is transmitted with a periodicity of 160 ms and variable transmission repetition periodicity within 160 ms
  • The default transmission repetition periodicity of SIB1 is 20 ms but the actual transmission repetition periodicity is up to network implementation

SIB2

  • SIB2 stands for System Information Block 2
  • SIB2 contains cell re-selection information common for intra-frequency, inter-frequency and/or inter-RAT cell re-selection (i.e. applicable for more than one type of cell re-selection but not necessarily all) as well as intra-frequency cell re-selection information other than neighbouring cell related.

SIB3

  • SIB3 stands for System Information Block 3
  • SIB3 contains neighbouring cell related information relevant only for intra-frequency cell re-selection. The IE includes cells with specific re-selection parameters as well as blacklisted cells.

SIB4

  • SIB4 stands for System Information Block 4
  • SIB4 contains information relevant only for inter-frequency cell re-selection i.e. information about other NR frequencies and inter-frequency neighbouring cells relevant for cell re-selection.
  • The IE includes cell re-selection parameters common for a frequency as well as cell specific re-selection parameters.

SIB5

  • SIB5 stands for System Information Block 5
  • SIB5 contains information relevant only for inter-RAT cell re-selection i.e. information about E-UTRA frequencies and E-UTRAs neighbouring cells relevant for cell re-selection.
  • The IE includes cell re-selection parameters common for a frequency.

SIB6

  • SIB6 stands for System Information Block 6
  • SIB6 contains an ETWS primary notification

SIB7

  • SIB7 stands for System Information Block 7
  • SIB7 contains an ETWS secondary notification

SIB8

  • SIB8 stands for System Information Block 8
  • SIB8 contains a CMAS notification

SIB9

  • SIB9 stands for System Information Block 9
  • SIB9 contains information related to GPS time and Coordinated Universal Time (UTC).
  • The UE may use the parameters provided in this system information block to obtain the UTC, the GPS and the local time

References

3GPP 38.300

3GPP 38.331

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