UTRAN Complete Signaling Sequences

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  • UTRAN and UMTS Radio Protocols 1

    Complete Signaling Sequences in UTRAN R

    Appendix A: Complete Signaling Sequences in UTRAN

    Complete signaling message sequence charts with Iu, Iub, Iur and Uu Protocols with focus on the functional protocols RANAP, NBAP, RNSAP, RRC.

  • UTRAN and UMTS Radio Protocols 2

    Complete Signaling Sequences in UTRAN R

    1. RRC Connection Setup into state CELL_DCH

    A UE has entered the area of a RNC and triggers now radio contact. The reason for the radio access is a higher layer service request coming from NAS protocols (e.g. MM, GMM, SM, CC, SMS, etc.). The following actions must be done:

    1. Random access: The UE accesses the RACH and sends the message RRC Connection Request.

    2. DCH Allocation: The RNC must now decide which channel to allocate. This decision is based upon the service the UE wants to have and upon the actual congestion level. The DCH requires set up of a communication context in the Node B (Radio Link Setup) and conguration of a AAL2 virtual channel that shall transport the established DCH. Additionally the channel between serving RNC and Node B must be synchronized (Downlink Synchronization and Uplink Synchronization).

    3. DCH Activation and RRC connection completion: When the DCH is prepared, the RNC informs the UE about the successful established RRC Connection and gives the UE all infor-mation about its new dedicated channel DCH (e.g. transport formats, physical layer parameters, RLC conguration). Now the UE will begin to send on the DCH and synchronize itself with the Node B. When this is successfully done, the UE and Node B will send an indication about the successfully synchronized radio link (RRC Connection Setup Complete and Radio Link Restore Indication).

    From the point of RRC states the UE begins the procedure in UTRA IDLE mode and leaves the procedure in CELL_DCH mode.

  • UTRAN and UMTS Radio Protocols 3

    Complete Signaling Sequences in UTRAN R

    RRC Connection Establishment to RRC State CELL_DCH

    Menu

    UE Node B RNCRACH:CCCH RRC Connection RequestRRC RRC

    allocate RNTI,select L1 and L2

    parameters

    NBAP NBAPRadio Link Setup

    start Rx

    NBAP NBAPRadio Link Setup Response

    ALCAP ALCAPEstablishment Request

    ALCAP ALCAPEstablishment Confirmed

    DCH-FPDCH-FPDownlink Synchronisation

    DCH-FPDCH-FPUplink Synchronisation

    start Tx

    FACH:CCCH RRC Connection SetupRRC RRC

    NBAP NBAPRadio Link Restore Indication

    DCH:DCCH RRC Connection Setup CompleteRRC RRC

  • UTRAN and UMTS Radio Protocols 4

    Complete Signaling Sequences in UTRAN R

    2. RRC Connection Establishment to RRC state CELL_FACH

    In the following sequence the UE again performs an access to get a RRC connection, but this time only a FACH is granted to the UE.

    1. Random Access:The UE access the RACH and sends RRC Connection Request. This message is received by the RNC. The RNC must again de-cide, which resources shall be granted to the UE. In the present case only the FACH/RACH will be accessible for the UE. Thus there is no need to allocate any resource on Iub or Uu.

    2. RRC connection establishment completion:The RNC indicates now the successful establishment of the RRC connection with RRC Connection Setup. In this message the UE gets the information to use the FACH/RACH as transport resources. The message itself is sent on the FACH. The UE will answer with RRC Connection Setup Complete on the RACH, this message requires a last acknowledgement on the FACH.

  • UTRAN and UMTS Radio Protocols 5

    Complete Signaling Sequences in UTRAN R

    RRC Connection Establishment to RRC State CELL_FACH

    Menu

    UE Node B RNC

    RACH:CCCH RRC Connection RequestRRC RRC

    allocate RNTI,

    FACH:CCCH RRC Connection SetupRRC RRC

    RACH:DCCH RRC Connection Setup CompleteRRC RRC

    FACH:CCCH RLC acknowledgement for RRC Connection Setup CompleteRRC RRC

  • UTRAN and UMTS Radio Protocols 6

    Complete Signaling Sequences in UTRAN R

    3. Radio Access Bearer Establishment from CELL_DCH with DCH Setup - synchronized

    The following procedure shows a radio access bearer setup triggered by the core network (MSC or SGSN). The UE is initially in RRC state CELL_DCH. This means a DCH already exists for the UE. The radio access bearer requires a DCH. The procedure will show as general case a soft handover situation, this means we will see two radio links (already existing) in two different Node B and one Node B belongs to the serving RNC and the other Node B belongs to a drift RNC.The procedure will be performed as so called synchronized radi link modication.

    1. Radio Access Bearer RequestThe core network will send the RANAP message RAB Assignment Request to the actual serving RNC of the UE. The RNC has to analyze the quality of service parameter for the RAB. These abstract parameters have to be mapped onto physical parameters for the setup of transport bearers on Iu, Iub, Iur and Uu.

    2. Iu Bearer Setup and Radio Link PreparationThe serving RNC begins now to set up all the individual bearer services. First of all the Iu bearer must be set up when a circuit switched service (Iu-CS) is wanted, for packet oriented services this is not necessary. Second the serving RNC triggers both Node B to prepare the radio link needed for the UE (Radio Link Reconguration Prepare). Because there is already a DCH, this one will simply be modied to fulll the requirements of the RAB. If both Node B have prepared the radio resources, they will send a Radio Link Reconguration Ready message to the serving RNC back. Concurrently with this the serving RNC triggers the establishment of AAL2 virtual channel resources for the radio link for Iub and Iur interfaces. These two ATM transport bearer resources require a synchronization between serving RNC and the Node B at the endpoint. This is done with the Iub/Iur frame protocols (Uplink Syn-chronization and Downlink Synchronization).

    3.Radio Bearer Setup CompletionNow that the radio link and the associated Iur/Iub transport bearer are established, it is time to change the DCH conguration. There-fore the serving RNC sends Radio Link Reconguration Commit to both Node B and the UE gets the Radio Bearer Setup message from it. The UE and the Node B will now apply the new transport formats and physical channel conguration and try to decode each other. If this is successful, the UE sends Radio Bearer Setup Complete to the serving RNC. This indicates a successful radio bearer setup. Thus the serving RNC can return RAB Assignment Response back to the core network with a success indication inside.

  • UTRAN and UMTS Radio Protocols 7

    Complete Signaling Sequences in UTRAN R

    Radio Access Bearer Establishment in state CELL_DCH with DCH required (synchronised) 1(2)

    Menu

    UENode BDrift RNS

    Node BServing RNS Drift RNC Serving RNC CN

    RAB Assignment RequestRANAP

    select Iu, Iub, Iur andUu bearer parameter

    RANAP

    ALCAP: Iu TransportBearer Setup (only Iu-CS)

    Radio Link ReconfigurationPrepare RNSAPRNSAP

    Radio Link Reconfiguration PrepareNBAPNBAP

    Radio Link Reconfiguration PrepareNBAPNBAP

    Radio Link Reconfiguration ReadyNBAPNBAP

    Radio Link Reconfiguration ReadyNBAPNBAP

    ALCAP: Iur TransportBearer Setup

    ALCAP: IubTransportBearer Setup

    ALCAP: IubTransportBearer Setup

    DCH-FPDCH-FP

    DCH-FPDCH-FP

    Downlink Synchronisation

    Downlink Synchronisation

    DCH-FPDCH-FP

    DCH-FPDCH-FP

    Uplink Synchronisation

    Uplink Synchronisation

    Radio Link ReconfigurationReady RNSAPRNSAP

  • UTRAN and UMTS Radio Protocols 8

    Complete Signaling Sequences in UTRAN R

  • UTRAN and UMTS Radio Protocols 9

    Complete Signaling Sequences in UTRAN R

    Radio Access Bearer Establishment in state CELL_DCH with DCH required (synchronised) 2(2)

    Menu

    UENode BDrift RNS

    Node BServing RNS Drift RNC Serving RNC CN

    Radio Link ReconfigurationCommit RNSAPRNSAP

    Radio Link Reconfiguration CommitNBAPNBAP

    Radio Link Reconfiguration CommitNBAPNBAP

    Radio Bearer SetupRRCRRC

    DCH:DCCH

    New Transport Formats will be applied on DCH

    Radio Bearer Setup CompleteRRCRRC

    DCH:DCCH

    RAB Assignment ResponseRANAPRANAP

  • UTRAN and UMTS Radio Protocols 10

    Complete Signaling Sequences in UTRAN R

    4. Radio Bearer Setup in state CELL_DCH with DCH required - unsynchronized

    The procedure presented before was synchronized. This means that before the radio link is really modied, the modication itself is prepared in both Node B. The modication itself is done synchronized when the serving RNC sends the message Relocation Commit. The following procedure is now unsynchronized, this means, both Node B will immediately modify the radio link without waiting for each other.

    1. Radio Access Bearer RequestThe core network will send the RANAP message RAB Assignment Request to the actual serving RNC of the UE. The RNC has to analyze the quality of service parameter for the RAB. These abstract parameters have to be mapped onto physical parameters for the setup of transport bearers on Iu, Iub, Iur and Uu.

    2. Iu Bearer Setup and Radio Link PreparationThe serving RNC begins now to set up all the individual bearer services. First of all the Iu bearer must be set up when a circuit switched service (Iu-CS) is wanted, for packet oriented services this is not necessary. Now the serving RNC triggers both Node B to modify the existing radio links (Radio Link Reconguration). Each Node B performs immediately the reconguration and returns the message Radio Link Reconguration Response. Concurrently with this the serving RNC triggers the establishment of AAL2 virtua