How UE knows a cell is barred or not?

Question

With respect to Intra-cell (oneENB multiple cells), each cell will have different PCI's(physical cell identity).
Whether all cells will have same systeminformation(MIB,SIB) or it will differ? OR It is implementation specific?

Answer 1

If the eNB cannot access any MME, then all cells of the eNB will be barred. When Cell is Barred eNB doesn't transmit anything or transmits the RS with a very low value, so UE doesn't receive anything. eNB can also inform UE that Cell is in Barred state through SIB1 as Salil Agrawal mentioned

SystemInformationBlockType1 ::= SEQUENCE {
cellAccessRelatedInfo SEQUENCE {
       plmn-IdentityList PLMN-IdentityList,
       trackingAreaCode TrackingAreaCode,
      cellIdentity CellIdentity,
    **cellBarred ENUMERATED {barred, notBarred},**
      intraFreqReselection ENUMERATED {allowed, notAllowed},
      csg-Indication BOOLEAN,
      csg-Identity CSG-Identity OPTIONAL -- Need OR
},  

As per Spec 36.331

Essential system information missing The UE shall:

1. If in RRC_IDLE or in RRC_CONNECTED while T311 is running:
   ¤ If the UE is unable to acquire the MasterInformationBlock or the SystemInformationBlockType1:
   - consider the cell as barred in accordance with TS 36.304; and
   - perform barring as if intraFreqReselection is set to allowed, and as if the csg-Indication is set to FALSE;

2. else if the UE is unable to acquire the SystemInformationBlockType2:
   ¤ Treat the cell as barred in accordance with TS 36.304;

Answer 2

Cell Barring status is Advertised in cellbarred of SIB1

Comments

i think when cell barring time ue considers ac barring info in sib2 correct me if i am wrong

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I think that is access class barring