System Information Block 1

After initial cell synchronisation and reading Master information block, UE will proceed to read system information blocks to obtain important cell access related parameters.

SIB1 broadcasts common information to all UEs in the cell related to cell access parameters and information related to scheduling of other SIBs. SIB1 is broadcasted in subframe # 5 in the SFN for which SFN mod 8 = 0. While the repeated copies are sent in subframe # 5 for which SFN mod 2 = 0 . Thus the new copy of SIB1 is transmitted every 80ms as shown below

The cell access related parameters are listed below

  • PLMN identity : Upto 6 PLMN identies can be specified
  • Tracking area code: Range from 0 to 65546
  • Cell Id: It contains eNB identity and has length of 28 bits
  • Cell barred: whether cell is barred or not
  • Intra Frequency cell reselection info: To select other cells when the target cell is barred
  • CSG indication: To indicate whether this cell is CSG cell or not. If it is CSG cell, then CSG identity stored in the UE should match with CSG id of the cell
Other information broadcasted by SIB 1 are 
  • q-RxLevMin: Minimum required level in the cell 
  • Band indicator: Cell frequency band indicator
  • scheduling information of other system information blocks
Complete SIB1 info is shown below (taken from UE logs). This SIB1 does not represent any real network


  1. Hello ,
    would it be possible to post a C struct of SIB1 ?

    1. Hi sorry, I do not have any such data or information

  2. Hi Adnan

    Great explanation of every thing. Could you please tell me the Slot # of SIB1 in Subframe # 5 ??
    Thanks in advance


  3. Is it possible to extract TDD configuration from SIB1?

    1. Yes, it will be broadcasted in case of TDD only.Tag:
      subframeAssignment: 1
      specialSubframePatterns: 5

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