LTE: RRC Connection Setup Complete

Direction: UE => E-UTRAN
Signalling Radio Bearer: SRB1
RLC Mode: AM
Logical Channel: DCCH
Transport Channel: UL-SCH


The RRC CONNECTION SETUP COMPLETE message is used to confirm the successful completion of an RRC connection establishment. Some of the IEs in this message are explained below:

selectedPLMN-Identity: This IE points to a PLMN-Id in the plmn-IdentityList of SIB1. The IE plmn-IdentityList is transmitted in SIB1 when the cell belong to more than one PLMN.The value of this IE equals to ‘1’ if the 1st PLMN is selected from the plmn-IdentityList included in SIB1, ‘2’ if the 2nd PLMN is selected from the plmn-IdentityList included in SIB1 and so on
registeredMME: This IE is optional, and is included when available. This is the identity of the MME with which the UE is (previously) registered with. If upper layers provide the 'Registered MME', then the IE registeredMME is set as follows:
If the PLMN identity of the 'Registered MME' is different from the PLMN selected by the upper layers (selectedPLMN-Identity) then include the plmnIdentity in the registeredMME and set the mmegi and the mmec to the value received from upper layers
 dedicatedInfoNAS: This IE includes the initial NAS message from the UE


Example1: RRC CONNECTION SETUP COMPLETE message without registeredMME IE

Example2: RRC CONNECTION SETUP COMPLETE message with registeredMME IE included




For your convenience, I have also decoded the dedicatedInfoNAS in the Example2 here


Reference: 3GPP TS 36.331
Posted by KP
Labels: ,

25 comments:

  1. AnonymousAugust 7, 2012 at 10:59 PM

    Does the Ue need to send Schedulng request to have grant to b able to send RRC setup complete? or the grant is included in RRC setup?

    Thanks

    ReplyDelete
  2. KPAugust 8, 2012 at 5:49 AM

    RRC connection setup can't include any grant, the grant has to be explicitly signaled to the UE on PDCCH (DCI 0) in order for the UE to send RRC Connection setup complete message. If the NW doesn't provide the grant by itself, then the UE has to send SR to request for the grant

    ReplyDelete
    Replies
    1. AnonymousAugust 13, 2012 at 10:14 AM

      Hi;

      This is my question as you said "IF THE NETWORK DOESN'T PROVIDE BY ITSELF" so what is the standard, for message3 the RBS autmatically send the grant included in msg2 so that Ue can send msg3 next,so it means for msg5 Ue has to request SR in the standard? is this correct?

      Thanks and appreciate your answer;

      Delete
  3. UnknownDecember 7, 2012 at 11:03 AM

    As for my understanding RRC Connection Setup does contain the IE
    +-schedulingRequestConfig ::= CHOICE [setup] OPTIONAL:Exist
    | +-setup ::= SEQUENCE
    | +-sr-PUCCH-ResourceIndex ::= INTEGER (0..2047) [20]
    | +-sr-ConfigIndex ::= INTEGER (0..155) [30]
    | +-dsr-TransMax ::= ENUMERATED [n4]
    +-nonCriticalExtension ::= SEQUENCE OPTIONAL:Omit

    which is an Optional

    Regards
    Neha

    ReplyDelete
  4. AnonymousOctober 10, 2013 at 10:28 AM

    Even though ULgrant is present to send RRC connection setup complete, are there any reasons that this message sending can fail OR network does not receive it? And network releasing the rrc connection as this message is not received? please answer.

    ReplyDelete
  5. AnonymousOctober 29, 2013 at 1:07 PM

    Hi Kumar,

    Is it SRB1 or SRB2 for this RRC CONNECTION COMPLETE message? The reason being I am asking is on one of the spec I have seen this below line.
    "SRB RB1 shall be used for all messages sent on the DCCH, when us-ing RLC unacknowledged mode (RLC-UM)"

    But here you said it is SRB1 with RLC-AM using DCCH. can you plz clarify this?

    ReplyDelete
  6. KPOctober 29, 2013 at 1:23 PM

    From 36.331, section 4.2.2,
    SRB0 is for RRC messages using the CCCH logical channel;

    SRB1 is for RRC messages (which may include a piggybacked NAS message) as well as for NAS messages prior to the establishment of SRB2, all using DCCH logical channel;

    SRB2 is for NAS messages, using DCCH logical channel. SRB2 has a lower-priority than SRB1 and is always configured by E-UTRAN after security activation

    ReplyDelete
    Replies
    1. AnonymousAugust 21, 2019 at 10:41 PM

      What a stupid answer, copy paste of 3GPP document

      Delete
  7. UnknownApril 22, 2014 at 9:37 AM

    From 36.331:
    The IE SchedulingRequestConfig is used to specify the Scheduling Request related parameters as follows.
    sr-PUCCH-ResourceIndex:The scheduling request (SR) shall be transmitted on this PUCCH resource
    sr-ConfigIndex : The SR configuration for SR transmission periodicity and and SR subframe offset
    dsr-TransMax: Parameter for SR transmission in TS 36.321 [6, 5.4.4]. The value n4 corresponds to 4 transmissions, n8 corresponds to 8 transmissions and so on.

    UE would need to send the SR according to the configuration mentioned in the schedulingRequestConfig IE.

    ReplyDelete
  8. UnknownAugust 23, 2014 at 11:59 AM

    Hi All,
    In my logs, for rrcConnectionSetupComplete, selectedPLMN-identity is 1 and registered MME = 250-11, whereas in SIB1 message, plmn-identity list showing 1 = 250-50 & 2 = 250-11.

    So "registered MME" in "rrcConnectionSetupComplete" is at 2nd index in SIB1 but "selectedPLMN-identity" showing 1.

    Please explain whether this is correct behaviour or not?

    ReplyDelete
  9. indu shekharAugust 26, 2014 at 2:09 PM

    This comment has been removed by the author.

    ReplyDelete
  10. indu shekharAugust 26, 2014 at 2:28 PM

    I have few questions on SIB 1 parameters.

    What is the purpose of sending a list of PLMN IDs in System Information 1?

    Is it possible that 1 cell can have multiple PLMN IDs ?

    Regards,

    ReplyDelete
    Replies
    1. KPSeptember 23, 2014 at 9:40 AM

      The purpose of multiple PLMNs is due to network sharing which is famously known as MOCN (Multi-Operator Core Network )

      A good link: http://netsecinfo.blogspot.se/2010/06/lte-network-sharing-using-mocn-enodeb.html

      Delete
  11. AnonymousFebruary 12, 2015 at 11:04 AM

    Hi,
    I am new to LTE. So I have this doubt whether
    the UE will sent all its capabilities in the RRCConnectionSetupComplete message, like in UMTS.
    Please clarify

    Thanks
    Anjana

    ReplyDelete
    Replies
    1. KPFebruary 16, 2015 at 1:40 PM

      Hi Anjana,
      The UE won't send its capabilities in RRCConnectionSetupComplete message, UEcapabilityInformation message is used instead.
      http://howltestuffworks.blogspot.se/2011/10/ue-capability-information.html

      Delete
  12. AnonymousJuly 27, 2015 at 2:05 PM

    Hi

    I am New to the LTE. My doubt is: why shoul we need both PLMN id as well as selected PLMN id in Connection complete message.
    What should EnodeB do after reception of the selected PLMN identity?

    Thanks
    Mainpal

    ReplyDelete
    Replies
    1. KPJuly 27, 2015 at 2:45 PM

      For the routing of the initial NAS message to the appropriate MME, the UE NAS provides the lower layers with either the S-TMSI or the registered globally unique MME identifier (GUMMEI) that consists of the PLMN ID, the MME group ID, and the MME code.

      @RRC,
      If upper layers provide the 'Registered MME', include and set the registeredMME as follows:
      - if the PLMN identity of the 'Registered MME' is different from the PLMN selected by the upper layers, include the plmnIdentity in the registeredMME and set it to the value of the PLMN identity in the 'Registered MME' received from upper layers;

      Delete
    2. KPJuly 28, 2015 at 1:47 PM

      For the routing of the initial NAS message to the appropriate MME, the UE NAS provides the lower layers with either the S-TMSI or the registered globally unique MME identifier (GUMMEI) that consists of the PLMN ID, the MME group ID, and the MME code.

      @RRC,
      If upper layers provide the 'Registered MME', include and set the registeredMME as follows:
      - if the PLMN identity of the 'Registered MME' is different from the PLMN selected by the upper layers, include the plmnIdentity in the registeredMME and set it to the value of the PLMN identity in the 'Registered MME' received from upper layers;

      Delete
    3. UnknownJune 1, 2017 at 11:52 AM

      This comment has been removed by the author.

      Delete
  13. UnknownJune 1, 2017 at 12:04 PM

    Hi Kumar Swamy,
    What is the reason for upper layers not sending Registered MME.

    From 36.331 and above description I see that,
    registeredMME: This IE is optional, and is included when available. This is the identity of the MME with which the UE is (previously) registered with.

    That means, if UE is in EMM DEregistered state, it should never send Registered MME IE in RRC Connection complete as it would not have previously registered MME data. But that's not the case.
    Can you please elaborate the scenario that would trigger RRC Connection Complete without registered MME IE.

    ReplyDelete
    Replies
    1. KPJune 1, 2017 at 10:14 PM


      From 24.301, section 4.3.7.3
      To off-load ECM-CONNECTED mode UEs, the MME initiates the S1 Release procedure with release cause "load balancing TAU required" (clause 5.3.5). The S1 and RRC connections are released and the UE initiates a TAU but provides neither the S-TMSI nor the GUMMEI to eNodeB in the RRC establishment.

      Delete
  14. UnknownDecember 12, 2017 at 12:43 AM

    Hi... What could be the reason for RRC connection setup failures due to complete message missing... And what action we can take to handle this...

    Thanks in advance

    ReplyDelete
    Replies
    1. KPJanuary 5, 2018 at 2:30 PM

      Hi Pankaj,

      You mean, the UE is not able to receive/decode RRC Connection Setup message at all?

      Delete
  15. DayashankarSeptember 25, 2020 at 5:29 PM

    Hi...

    Is rrc connection complete msg integrity protected or not?

    ReplyDelete
  16. sandeepMarch 21, 2021 at 4:41 AM

    No

    ReplyDelete

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