Techlte Blog

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

MIB (Master Information Block)

MIB – Master Information Block

Periodicity – 40 ms at RRC (10 ms at Physical Layer)

Location – 1st Subframe 2nd  Time Slot First 4rth  OFDM Symbol

Channel – PBCH

Information Elements (I.E)- 

  • SFN
  • Number of Tx Antenna
  • Bandwidth
  • PHICH info
  • PCID (Physical Cell ID)

SIB (System Information Block)

Types of SIB:

  • SIB 1 : Cell Selection, Cell Access, SI Scheduling.
  • SIB 2 : RACH, Access Barring, UL frequency Information, MBSFN Config.
  • SIB 3 : Intra Frequency Cell Reselection.
  • SIB 4 : Intra Frequency Neighbour Cell.
  • SIB 5 : Inter Frequency Neighbour Cell.
  • SIB 6 : UTRAN Neighbour Cell.
  • SIB 7 : GERAN Neighbour Cell.

Note : SIBs other than SIB1 are carried in SI messages and mapping of SIBs to SI is done by “schedulingInfoList” List include in SIB1.

System Information Block Type1 (SIB 1)

  • SIB1 : It contains information relevant when evaluating if a UE is allowed to access a cell and defines the scheduling of other system information.
  • Its periodicity is of 80 ms and repetitions made within 80 ms.

SIB1 related information:

plmn-IdentityList : List of PLMN identities.

sib-MappingInfo : List of the SIBs mapped to this SI message. There is no mapping information of SIB2, it is always present in the first SI message listed in schedulingInfoList list.

si-Periodicity : Periodicity of the SI-message in radio frames.

Si-WindowLength: Common SI scheduling window for all SI’s.

trackingAreaCode : trackingAreaCode that is common for all the PLMNs listed

systemInfoValueTag : indicates if a change has occurred in the SI messages.schedulingInfoList : The transmission cycles for other SIBs are determined

System Information Block Type2 (SIB 2)

  • There is no mapping information of SIB2
  • It is always present in the first System Information message listed in the schedulingInfoList list.
ac-BarringInfoAccess Class Barring configuration
radioResourceConfigused to specify common radio resource configurations in the system information and in the mobility control information
numberOfRA_PreamblesNumber of non-dedicated random access preambles
preamblesGroupAConfig_existProvides the configuration for preamble grouping. If the field is not signalled, the size of the random access preambles group A is equal to numberOfRA-Preambles
preambleTransMaxMaximum number of preamble transmission
ra_ResponseWindowSizeDuration of the RA response window. Value in subframes. Value sf2 corresponds to 2 subframes
mac_ContentionResolutionTimerTimer for contention resolution. Value in subframes. Value sf8 corresponds to 8 subframes
maxHARQ_Msg3Tx 4Maximum number of Msg3 HARQ transmissions, used for contention based random access
prach_Configused to specify the PRACH configuration in the system information and in the mobility control information
prach_ConfigIndexMentions Preamble format, SFN,subframe number

System Information Block Type3 (SIB 3)

Direction: E-UTRAN => UE

RLC Mode: TM

Logical Channel: BCCH

Transport Channel: DL-SCH

The SIB3 contains cell re-selection information common for intra-frequency, inter-frequency and/or inter-RAT cell re-selection.

SIB3 also contains cell reselection priority information for the concerned carrier frequency or a set of frequencies