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
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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
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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 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 Synchronization and Downlink Synchronization).
3.Radio Bearer Setup CompletionThe serving RNC sends now the Radio Bearer Setup message to the UE. 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.
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Complete Signaling Sequences in UTRAN R
Radio Access Bearer Establishment in state CELL_DCH with DCH required (unsynchronised) 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 ReconfigurationRequest RNSAPRNSAP
Radio Link Reconfiguration RequestNBAPNBAP
Radio Link Reconfiguration RequestNBAPNBAP
Radio Link Reconfiguration ResponseNBAPNBAP
Radio Link Reconfiguration ResponseNBAPNBAP
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 ReconfigurationResponse RNSAPRNSAP
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Complete Signaling Sequences in UTRAN R
UTRAN and UMTS Radio Protocols 13
Complete Signaling Sequences in UTRAN R
Radio Access Bearer Establishment in state CELL_DCH with DCH required (unsynchronised) 2(2)
Menu
UENode BDrift RNS
Node BServing RNS Drift RNC Serving RNC CN
Radio Bearer SetupRRCRRC
DCH:DCCH
New Transport Formats will be applied on DCH
Radio Bearer Setup CompleteRRCRRC
DCH:DCCH
RAB Assignment ResponseRANAPRANAP
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Complete Signaling Sequences in UTRAN R
5.Radio Bearer Setup in RRC state CELL_FACH with DCH required
In the two radio bearer setup procedures before always a DCH already existed. Now we look to the radio bearer setup with DCH from state CELL_FACH. This means currently there is no DCH before the radio bearer setup begins.
1. Radio Access Bearer RequestThe core network requests the radio access bearer with the message RAB Assignment Request. The message contains the abstract quality of service description of the transport resources required. The RNC maps these abstract parameters to the individual links.
2. Bearer SetupThe RNC triggers the setup of Iu bearer resources when circuit switched resources are needed. Next the DCH must be congured, but currently there is no radio link. Hence the serving RNC sets up a communication context with one radio link in one of its Node B. This is done with the message Radio Link Setup. The Node B acknowledges with Radio Link Setup Response. For the congured DCH a transport resource on Iub is needed, hence the serving RNC congures an AAL2 virtual channel for DCH transport. This Iub bearer is now synchronized between Node B and serving RNC.
3. Radio Bearer Setup CompletionThe UE gets now the Radio Bearer Setup message in which it nds the conguration parameters for the DCH. So the UE applies these parameters and tries to synchronize the radio link with the Node B. If this is successful, the UE shall send Radio Bearer Setup Complete and the Node B shall issue Radio Link Restore Indication to the serving RNC. This concludes the radio bearer setup, thus the serving RNC can acknowledge with RAB Assignment Response to the core network.
UTRAN and UMTS Radio Protocols 15
Complete Signaling Sequences in UTRAN R
Radio Access Bearer Establishment in state CELL_FACH with DCH required
Menu
UENode BDrift RNS
Node BServing RNS Drift RNC Serving RNC CN
RAB Assignment RequestRANAP
select Iu, Iub andUu bearer parameter
RANAP
ALCAP: Iu TransportBearer Setup (only Iu-CS)
Radio Link Setup RequestNBAPNBAP
Radio Link Setup ResponseNBAPNBAP
ALCAP: IubTransportBearer Setup
DCH-FPDCH-FPDownlink Synchronisation
DCH-FPDCH-FPUplink Synchronisation
Radio Bearer SetupRRCRRC
FACH:DCCH
Radio Bearer Setup CompleteRRCRRC
DCH:DCCH
RAB Assignment ResponseRANAPRANAP
Radio Link Restore IndicationNBAPNBAP
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Complete Signaling Sequences in UTRAN R
6. Radio Bearer Setup in RRC state CELL_FACH with FACH required
If a UE gets a radio access bearer without DCH, then there is no need for dynamical transport bearer setup on Uu and Iub. This is because the common transport channel resources are precongured by the operator via O&M. So the radio bearer setup is relatively simple in this case.
1. Radio Access Bearer RequestThe core network requests the radio access bearer with RAB Assignment Request. The serving RNC analyzes the abstract RAB description inside and derives the individual link parameters for Iu, Iub and Uu.
2. Bearer SetupIn the present case the RAB requires no DCH and the UE will only get the FACH/RACH common transport channel resources. The RACH and FACH radio transport channels are already congured during cell setup. The same holds for the Iub ATM transport re-sources associated with RACH and FACH. Thus the only bearer that might need dynamical conguration can be the Iu bearer, but this is necessary for Iu-CS only. Hence the only thing to do is to tell the UE with Radio Bearer Setup to use FACH/RACH. The UE acknowledges with Radio Bearer Setup Complete. This message will be acknowledged. This concludes the RAB setup.
UTRAN and UMTS Radio Protocols 17
Complete Signaling Sequences in UTRAN R
Radio Access Bearer Establishment in state CELL_FACH with FACH required
Menu
UENode BDrift RNS
Node BServing RNS Drift RNC Serving RNC CN
RAB Assignment RequestRANAP
select Iu, Iub andUu bearer parameter
RANAP
ALCAP: Iu TransportBearer Setup (only Iu-CS)
Radio Bearer SetupRRCRRC
FACH:DCCH
Radio Bearer Setup CompleteRRCRRC
RACH:DCCH
RAB Assignment ResponseRANAPRANAP
RLC Acknowledgement for Radio Bearer Setup CompleteRRCRRC
FACH:DCCH
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Complete Signaling Sequences in UTRAN R
7. Soft Handover - Radio Link Addition and Deletion
Consider a UE that has multiple radio links with Node B directly connected to the actual serving RNC. So the UE is in a soft handover situ-ation. The present case describes the procedure when one radio link between UE and a Node B connected to the serving RNC is deleted and in the same procedure a new radio link between the UE and a Node B connected to a drift RNC is added.
1. Preparation of new radio linkFirst of all the serving RNC must prepare the new radio link that shall be added. Therefore a communication context within the new Node B in the drift RNS has to be created, this happens with the Radio Link Setup message. It commands the Node B to decode the UEs uplink scrambling code and to send data to the UE with a downlink scrambling code of the Node B. When the new radio link is prepared the Node B acknowledges with Radio Link Setup Response. After this the Iur and Iub ATM transport resources must be prepared. This resource is synchronized between Node B and serving RNC. Because the UE is already sending on its scrambling code, the Node B can already detect the UEs signal, hence it will send Radio Link Restore Indication to the serving RNC.
2. Active Set UpdateNow that the new radio link is prepared and the Node B already uplink data from the UE receives, the serving RNC must tell the UE also to decode the new downlink scrambling code of the new Node B. Therefore the serving RNC sends Active Set Update to the UE which will especially contain the new downlink scrambling code to decode. In the same message the UE can be advised to no longer decode an obsolete, old downlink scrambling code. The UE acknowledges with Active Set Update Complete.
3. Deletion of the old radio linkThe old radio link that is no longer decoded by the UE must now be released in the associated Node B. Hence the serving RNC sends a Radio Link Deletion message to it. The Node B will remove the radio link. If this was the last radio link in the communication context for the UE, the context is deleted too.
UTRAN and UMTS Radio Protocols 19
Complete Signaling Sequences in UTRAN R
Soft Handover - Radio Link Addition and Deletion 1(2)
Menu
UENode BDrift RNS
Node BServing RNS Drift RNC Serving RNC CN
Radio Link Setup RequestRNSAPRNSAP
Radio Link Setup RequestNBAPNBAP
decision to add anddelete a radio link
start Rx
Radio Link Setup ResponseNBAPNBAP
Radio Link Setup ResponseRNSAPRNSAP
ALCAP: Iur TransportBearer Setup
ALCAP: IubTransportBearer Setup
Radio Link Restore IndicationNBAPNBAP
Radio Link Restore IndicationRNSAPRNSAP
DCH-FPDCH-FPDownlink Synchronisation
DCH-FPDCH-FPUplink Synchronisation
start Tx
UTRAN and UMTS Radio Protocols 20
Complete Signaling Sequences in UTRAN R
UTRAN and UMTS Radio Protocols 21
Complete Signaling Sequences in UTRAN R
Soft Handover - Radio Link Addition and Deletion 2(2)
Menu
UENode BDrift RNS
Node BServing RNS Drift RNC Serving RNC CN
Radio Link Deletion RequestNBAPNBAP
Radio Link Deletion ResponseNBAPNBAP
ALCAP: IubTransportBearer Release
stop Rx and Tx
Active Set UpdateRRCRRC
DCH:DCCH
Active Set Update CompleteRRCRRC
DCH:DCCH
(add radio link X, delete radio link Y)
UTRAN and UMTS Radio Protocols 22
Complete Signaling Sequences in UTRAN R
8. Hard Handover without Serving RNC Relocation
The following use case describes a hard handover, where the UE changes Node B and both Node B belong to drift RNC and not to the serving RNC. The presented ow is therefore the most general one and can easily be reduced to cases where some RNC are equal.
1. Handover Decision and PreparationThe serving RNC decide upon the handover based on the radio measurements made by UE and Node B. Before the handover can be started, the new radio link resources in the new (target) Node B must be prepared. Hence the serrving RNC triggers the setup of a communication context together with a radio link (Radio Link Setup Request). When the radio resources in the target Node B are prepared and the associated Iub ATM transport bearer resources between target Node B and target RNC is prepared, the serv-ing RNC will be informed about it (Radio Link Setup Response). The serving RNC can now trigger the establishment of an Iur ATM transport bearer. The Iub/Iur ATM transport bearer will be synchronized between target Node B and serving RNC.
2. Handover ExecutionThe UE begins handover execution when the serving RNC sends a reconguration message to it (Physical Channel Recongura-tion). The UE immediately begins to modify its radio links. Hence the old (source) Node B loses the radio contact and therefore makes a Radio Link Failure Indication. In contrast to that the target Node B will now receive the signal of the UE and hence sends a Radio Link Restore Indication. In the same way the UE indicates the successful reception of the target RNC radio signal with a reconguration completion indication (Physical Channel Reconguration Complete).
3. Garbage CollectionIt remains to remove the radio and Iub/Iur resources of the old radio link. Therefore the serving RNC sends a Radio Link Deletion message to the source Node B. This message will delete the radio link and when it was the last radio link, the communication context in the source Node B will be deleted too. Last the Iub/Iur ATM transport resources to and from the source Node B can be cleared.
UTRAN and UMTS Radio Protocols 23
Complete Signaling Sequences in UTRAN R
Hard Handover between different RNC without S-RNC relocation 1(2)
Menu
UENode B
Target RNSNode B
Source RNS Target RNC Source RNC Serving RNC
NBAP
ALCAP: IubTransportBearer Establishment
HandoverDecision
RRC
DCH-FP
RNSAP
Physical Channel Reconfiguration
Radio Link Setup RequestRNSAP
Radio Link Setup RequestNBAP
start Rx
NBAPRadio Link Setup Response
NBAP
RNSAPRadio Link Setup Response
RNSAP
RRCDCH:DCCH
DCH-FPDownlink Synchronisation
DCH-FPDCH-FPUplink Synchronisation
NBAPRadio Link Failure Indication
NBAP
RNSAPRNSAPRadio Link Failure Indication
ALCAP: IurTransportBearer Establishment
UTRAN and UMTS Radio Protocols 24
Complete Signaling Sequences in UTRAN R
UTRAN and UMTS Radio Protocols 25
Complete Signaling Sequences in UTRAN R
Hard Handover between different RNC without S-RNC relocation 2(2)
Menu
UENode B
Target RNSNode B
Source RNS Target RNC Source RNC Serving RNC
NBAP
ALCAP: IubTransportBearer Release
RRC
ALCAP: Iur TransportBearer Release
RNSAP
Physical Channel Reconfiguration Complete
Radio Link Deletion RequestRNSAP
Radio Link Deletion RequestNBAP
NBAPRadio Link Deletion Response
NBAP
RRCDCH:DCCH
NBAPRadio Link Restore Indication
NBAP
RNSAPRNSAPRadio Link Restore Indication
RNSAPRadio Link Deletion Response
RNSAP
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Complete Signaling Sequences in UTRAN R
9. Hard Handover with Serving RNC Relocation
The following scenario shows a hard handover associated with a relocation of the serving RNC. The serving RNC at the begin of the pro-cedure is labelled as source RNC, whereas the RNC that shall be the serving RNC at the end of the procedure is called target RNC. The procedure is presented for the case that there is a signaling connection towards SGSN and MSC. A change of MSC (inter-MSC handover) or a change of SGSN is not considered here.
1. Relocation Indication and PreparationThe decision to perform a relocation together with hard handover comes exclusively fromt the actual serving (source) RNC. The Relocation Required message indicates the relocation to the core network. MSC and SGSN shall prepare the relocation and inform the target RNC with Relocation Request. This triggers the target RNC to prepare the radio access bearer resources for the UE. In detail this means for the target RNC to set up an Iu ATM transport bearer towards MSC, to allocate the radio link for the UE in the new Node B (Radio Link Setup) and with this the associated Iub ATM transport bearer for the DCH is needed. The Iub transport bearer must be synchronized. When all is done, the target RNC sends an acknowledgement (Relocation Request Acknowledge) back to each core network domain.
2. Relocation ExecutionTo start relocation both CN domains must send Relocation Command to the source RNC. When this happened, the UE will get the a message that indicates the new radio resources for it (Physical Channel Reconguration). So the UE now tunes to the new radio link in the target Node B. Therefore the target Node B will send the Radio Link Restore Indication to target RNC, which will forward this indication as Relocation Detect. In the same way the source Node B will loose the radio link and sends Radio Link Failure Indication to the source RNC. When the UE concludes the radio link change, it will send Physical Channel Reconguration Complete on the new resource to the target RNC. This triggers the Relocation Complete message to both CN domains.
3. Garbage CollectionThe resources in the source RNC and source Node B are no longer needed. Thus the core network will delete all resources with Iu Release Command.
UTRAN and UMTS Radio Protocols 27
Complete Signaling Sequences in UTRAN R
Hard Handover between different RNC with S-RNC relocation 1(3)
Menu
UENode B
Target RNSNode B
Source RNS Target RNC Source RNC SGSN MSC
NBAP
DCH-FP
Radio Link Setup RequestNBAP
DCH-FPDownlink Synchronisation
ALCAP: Iu TransportBearer Establishment for Iu-CS
RANAPRANAPRelocation Required
RANAP RANAPRelocation Required
RANAPRANAPRelocation Request
RANAPRANAPRelocation Request
NBAPRadio Link Setup Response
NBAP
ALCAP: Iub TransportBearer Establishment
DCH-FPDCH-FPUplink Synchronisation
RANAPRANAPRelocation Request Acknowledge
RANAPRANAPRelocation Request Acknowledge
UTRAN and UMTS Radio Protocols 28
Complete Signaling Sequences in UTRAN R
Hard Handover between different RNC with S-RNC relocation 2(3)
Menu
UENode B
Target RNSNode B
Source RNS Target RNC Source RNC SGSN MSC
RANAPRANAPReloocation Command
RANAP RANAPRelocation Commnand
NBAPRadio Link Restore Indication
NBAP
RANAPRANAPRelocation Detect
RANAPRANAPRelocation Detect
RRCRRCPhysical Channel Reconfiguration
NBAPRadio Link Failure Indication
NBAP
RRCRRCPhysical Channel Reconfiguration Complete
RANAPRANAPRelocation Complete
RANAPRANAPRelocation Complete
UTRAN and UMTS Radio Protocols 29
Complete Signaling Sequences in UTRAN R
Hard Handover between different RNC with S-RNC relocation 3(3)
Menu
UENode B
Target RNSNode B
Source RNS Target RNC Source RNC SGSN MSC
NBAPRadio Link Deletion
NBAP
RANAPRANAPIu Release Command
RANAP RANAPIu Release Command
NBAPRadio Link Deletion Response
NBAP
ALCAP: IuTransportBearer Release
ALCAP: IubTransportBearer Release
RANAPRANAPIu Release Complete
RANAP RANAPIu Release Complete
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Complete Signaling Sequences in UTRAN R
10. Switch from CELL_DCH to CELL_FACH with Drift RNC
Based on the trafc measurements for a radio bearer the serving RNC must decide whether the UE shall be kept in state CELL_DCH utilizing a dedicated channel DCH or the UE must be sent to state CELL_FACH without a dedicated resource. In the present procedure the UE is currently located in a cell belonging to a drift RNC. At the start of the procedure the UE has one radio link in this cell.
1 Preparation of new resourcesWhen the serving RNC decides to switch the UEs state to CELL_FACH because there trafc is low, it is necessary to prepare the FACH and RACH transport resources. Because the UE is actually located in a cell of a drift RNC, this requires the set up of ATM transport resources for RACH and FACH and the remote allocation of bandwidth on these common transport channels. The latter is achieved with the RNSAP messages Common Transport Channel Resource Request. The ATM resources are then established.
2 Radio Bearer modicationTo activate the switching to CELL_FACH the UE must be informed about the change with respect to the transport channel modica-tion. Hence the serving RNC sends the RRC message Transport Channel Reconguration via the still existing DCH to the UE. The UE must now modify its radio conguration and when done conrm with Transport Channel Reconguration Complete.
3 Release of old resourcesNow the resources associated with the obsolete DCH can be released.
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Complete Signaling Sequences in UTRAN R
Switch from CELL_DCH to CELL_FACH with Drift RNC
Menu
UENode BDrift RNS
Node BServing RNS Drift RNC Serving RNC CN
NBAP
ALCAP: IubTransportBearer Release
decision to switchfrom CELL_DCH to
CELL_FACH
RRC
ALCAP: IurTransport BearerConfiguration if needed
RNSAP
Transport Channel Reconfiguration
Common TransportChannel Resource Request
RNSAP
RNSAP
Common TransportChannel Resource Response
RNSAP
RRC
RRCTransport Channel Reconfiguration Complete
RRC
DCCH:DCH
DCCH:RACH
RNSAPRadio Link Deletion Request
RNSAP
NBAPRadio Link Deletion Request
NBAP
RNSAPRadio Link Deletion Response
RNSAP
NBAPRadio Link Deletion Response
ALCAP: IurTransportBearer Release
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Complete Signaling Sequences in UTRAN R
11. Cell Update without Serving RNC Relocation
When the UE is in state CELL_FACH, it will perform cell reselection and with this must perform cell updates to keep the serving RNC in-formed about its location. In this situation it can happen, that the UE enters a cell not belonging to the serving RNC area. Thus the servin g RNC must forward the cell update message to the serving RNC. In detail the procedure looks the following way:
1 Cell UpdateThe UE sends the RRC message Cell Update on RACH to the reselected cell. This message is received by the controlling RNC of the cell which is not the serving RNC of the UE. Inside the message the UE indicates its U-RNTI composed of S-RNC-ID and S-RNTI. From this the controlling RNC will know, that it is not the serving one for the UE. Hence the controlling RNC will forward the cell update message inside of a RNSAP message to the corresponding S-RNC.
2 Common Transport Channel Resource PreparationThe serving RNC has to decide to perform a relocation or not. In the present case there will be no relocation. Therefore the S-RNC triggers the foreign RNC to allocate resources for FACH/RACH. This is done with the RNSAP operation Common Transport Channel Resource Request. Possibly this can mean, that ATM transport resources on Iur have to be set up.
3 Procedure CompletionThe serving RNC can now indicate the successful cell update with RRC message Cell Update Complete. In this message the UE can be told to recongure its radio resources (transport channel, physical channel, radio bearer). In the present case there is no recon-iguration, which triggers the UE to complete the procedure with RRC message UTRAN Mobility Information Conrm. It remains to release the common transport channel resources in the old radio subsystem, hence the S-RNC sends the RNSAP message Com-mon Transport Channel Resource Release.
UTRAN and UMTS Radio Protocols 33
Complete Signaling Sequences in UTRAN R
Cell Update to a new Drift RNC without Serving RNC Relocation in RRC state CELL_FACH
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UENode B
Target Drift RNSNode B
Source Drift RNS Target Drift RNC Source Drift RNC Serving RNC
ALCAP: IurTransportBearer Configuration if needed
Decision NOTto make relocation
RRC
RNSAP
Cell UpdateRRC
CCCH:RACH
RNSAPUplink Signaling Transfer
(RRC Message: Cell Update)
RNSAPRNSAPCommon Transport Channel Resource Request
RNSAPRNSAPCommon Transport Channel Resource Response
RRC RRCCell Update Complete
RRC RRCUTRAN Mobility Information Confirm
RNSAPRNSAP
Common Transport ChannelResource Release
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