LTE: UE Identities

S-TMSI:
      S-TMSI (SAE-Temporary Mobile Subscriber Identity) is a temporary UE identity provided by the EPC which uniquely identifies the UE within the tracking area
      The S-TMSI is the shortened form of the GUTI to enable more efficient radio signalling procedures (e.g. paging and Service Request). For paging purposes, the mobile is paged with the S-TMSI. The S-TMSI shall be constructed from the MMEC and the M-TMSI
      The UE shall include S-TMSI in the RRC Connection Request message if (provided by the upper layers) the UE is registered in the TA of the current cell
<S-TMSI> = <MMEC><M-TMSI>

10 comments:

  1. Hi, can you please explain when does UE use IMSI in attach request and when does it use GUTI ? Its a bit confusing for me. Please explain abit in more detail

    ReplyDelete
  2. I the first time in attach request network request ue to give identity(GUTI).If it is invalid,then network will ask IMSI through(Identity request).one more time network will ask identity(IMEI this is optional).

    Am i correct

    ReplyDelete
    Replies
    1. Yes, when GUTI sent in attach request become invalid due to change in MME of UE. eNodeB ask for identity request. In response to this UE will send IMSI to identify itself.

      Delete
    2. I believe that the IMSI will not sent by UE if the MME changed , it suppose to check the GUTI and after that the new MME contact the previous MMEGI and MMEC to verify the UE , then the new MME will allocate new GUTI to UE and attach it to the network,

      This is in my perspective

      Delete
  3. Hi! Can you explain deffrenece beetween GUTI and S-TMSI?

    ReplyDelete
  4. Can anybody explain the types of paging & their procedures

    ReplyDelete
  5. Who will assign the GUTI & TMSI ID whether mobile or Network

    ReplyDelete
  6. The GUTI (Globally Unique Temporary ID) is a worldwide unique identity that points to a specific subscriber context in a specific MME. The S-TMSI is unique within a particular area of a single network. The UE can use the S-TMSI when communicating with the network as long as it stays within a TA that is part of the TA list it has received.

    ReplyDelete
  7. What happen id S-TMSI is not available in UE?

    ReplyDelete