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UMTS UTRAN Signaling ProceduresUMTS UTRAN Signaling Procedures1.01.0
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Course ContentsCourse Contents
Chapter 1 UTRAN Network OverviewUTRAN Network Overview
Chapter 2 Basic Signaling Process
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UTRAN OverviewUTRAN Overview
UE Working Mode and State
Serving RNC、 Drift RNC and Control RNC
Source RNC and Target RNC
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UE Working Modes and states UE Working Modes and statesIdle Mode
The UE has no relation to UTRAN, only to CN. For data transfer,
a signalling connection has to be established.
UE camps on a cell
It enables the UE to receive system information from the PLMN
When registered and if the UE wishes to establish an RRC
connection, it can do this by initially accessing the network on the
control channel of the cell on which it is camped
UE can receive "paging" message from control channels of the cell.
It enables the UE to receive cell broadcast services.
The idle mode tasks can be subdivided into three processes:
PLMN selection and reselection;
Cell selection and reselection;
Location registration.
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UE Working Modes and states UE Working Modes and states
Connected Mode (Cell-DCH, Cell-FACH, Cell-PCH, URA-PC
H)
When at least one signalling connection exists, the UE is in
connected mode and there is normally an RRC connection
between UE and UTRAN. The UE position can be known on
different levels:
UTRAN Registration Area (URA) level
The UE position is known on URA level. The URA is a set of cells
Cell level
The UE position is known on cell level. Different transport channel
types can be used for data transfer:
Common transport channels (RACH / FACH, DSCH, CPCH)
Dedicated transport CHannels (DCH)
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UE Working Modes and states UE Working Modes and states
Cell-DCH
In active state
Communicating via its dedicated channels
UTRAN knows which cell UE is in.
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Cell-FACH and Cell-PCH State Cell-FACH and Cell-PCH State
Cell-FACH
In active state
Few data to be transmitted both in uplink and in downlink. There is no
need to allocate dedicated channel for this UE.
Downlink uses FACH and uplink uses RACH.
UE need to monitor the FACH for its relative information.
UTRAN knows which cell UE is in.
Cell-PCH
No data to be transmitted or received.
Monitor PICH, to receive its paging.
lower the power consumption of UE.
UTRAN knows which cell UE is in.
UTRAN have to update cell information of UE when UE roams to
another cell
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URA-PCH StateURA-PCH State
URA-PCH
No data to be transmitted or received.
Monitor PICH.
UTRAN only knows which URA (UTRAN Registration Area,
which consists of multiple cells) that UE is in.
UTRAN update UE information only after UE has roamed to
other URA.
A better way to lower the resource occupancy and signaling
transmission
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UE states
CELL_DCH CELL_FACH
CELL_PCHURA_PCH
IDLE
DEAD - Scanning networks (PLMN)- ”Camp on” cell
- Monitor paging channel- cell re-selection
- Dedicated Channel- Radio bearers Transmission Services - upper layer Signaling
trigger (CN)
- Reduce action , DTX , and save power
RRC connection
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SRNC/DRNCSRNC/DRNC
SRNC and DRNC are on a per connection basis between a UE
and the UTRAN
The SRNC handles the connection to one UE, and may borrow ra
dio resources of a certain cell from the DRNC
Drift RNSs support the Serving RNS by providing radio resources
A UE in connection state has at least one and only one SRNC, but
can has 0 or multiple DRNCs
CN
SRNC DRNCIu
Iur
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CRNCCRNC
The CRNC owns the radio resources of a cell
Dynamical control of power for dedicated channels, within
limits admitted by CRNC, is done by the SRNC.
Scheduling of data for dedicated channels is done by the
SRNC, while for common channels it is done by the CRNC
CRNC
Iub
Node BCell Cell Cell
Node B
...
CN
Iu
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Source RNC/Target RNCSource RNC/Target RNC
The SRNS Relocation function coordinates the activities when the
SRNS role is to be taken over by another RNS.
Source RNC is the SRNC before SRNs Relocation and Target RN
C is the SRNC after SRNs Relocation
CNCN
Source RNC
TargetRNC
ServingRNC
Iu IuIur RNC
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Course ContentsCourse Contents
Chapter 1 UTRAN Network OverviewChapter 1 UTRAN Network Overview
Chapter 2 Basic Signaling ProcessBasic Signaling Process
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Basic Signaling Procedures
2.1 Call overall process
2.2 Network start process
2.3 UE registration process
2.4 Call process
2.5 Connection mobility management process
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Call overall ProceduresNetwork side Start
1、 Initialize equipment2、 Process system
broadcast
Step 1Handset Power on
1、 cell reselection2、 Location registration
3、Waiting for call
Step 2Paging UE
Step 3
RRC connection
Establish
Step 4
NAS signaling
connection establish
Step 5RAB set up
1、 synchronous set up2、 asynchronous set up
Step 6RAB/RB modification
Step 6Transport channel
reconfiguration
Step 6Physical channel
reconfiguration
Step 6Soft/hard handover
Step 6URA update
Step 6Cell update
Step 6Handover with GSM
Step 7RRC connection
release
Step 8Waiting for call again
1、 cell selection2、 wait for call
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Basic Signaling Procedures
2.1 Call overall process
2.2 Network start process
2.3 UE registration process
2.4 Call process
2.5 Connection mobility management process
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System Information Broadcast Flow
. 3.BCCH:System Information
1.System Information Update Request
UE Node B RNC CN
NBAPNBAP
RRCRRC
. 4.BCCH:System Information RRCRRC
5.BCCH:System Information RRCRRC
. 2.System Information Update Response
NBAPNBAP
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Basic Signaling Procedures
2.1 Call overall process
2.2 Network start process
2.3 UE registration process
2.4 Call process
2.5 Connection mobility management process
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RRC Connection Establishment Flow(CCH)
UE SRNC
RRC: RRC CONNECTION REQUEST
RRC: RRC CONNECTION SETUP
RRC: RRC CONNECTION SETUP COMPLETE
NodeB
UE originate RRC connection setup for registration.SRNC decides to establish RRC connection on common channel,and uses pre-configured common channel resources.
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NAS Signaling Establishment Flow
UE SRNC CN
RRC£ ºINITIAL DIRECT TRANSFER
RANAP: INITIAL UE MESSAGE
RRC£ ºDTRANAP£ ºDT
RANAP£ ºDT
RRC£ ºDT
UE changes DT messages with CN, such as Authentication, connection establishment, location registration, etc.
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RRC Connection Release Flow(CCH)
UE NodeB SRNC
IU RELEASE COMMAND
IU RELEASE COMPLETE
RRC£ ºRRC CONNECTION RELEASE
RRC£ ºRRC CONNECTION RELEASE COMPLETE
CN
In registration process, UE does not use dedicated user plane resources. Instead, it release signaling link directly. Thus registration procedure ends.
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Basic Signaling Procedures
2.1 Call overall process
2.2 Network start process
2.3 UE registration process
2.4 Call process
2.5 Connection mobility management process
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Paging Flow (UE in Idle State or PCH State)
CNSRNCUE
RANAP£ ºPAGING
RRC£ ºPAGING TYPE 1
CN sends paging message and specifies UE and paging area. ( CN is responsible for paging message re-send) . SRNC sends relevant paging message according to UE state.
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Paging Flow (connection mode)
CN sends paging message and specifies UE and paging area. ( CN is responsible for paging message re-send) . SRNC sends relevant paging message according to UE state.
UE ServingRNC
CN
RRCRRC2. DCCH : Paging
RANAP RANAP1. Paging
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RRC Connection Establishment Flow(DCH)
5. Downlink Synchronisation
UE Node B Serving RNS
Serving RNC
DCH-FP DCH-FP
Allocate RNTI Select L1 and L2
parameters
RRC RRC
1. CCCH : RRC Connection Request
NBAP NBAP
3. Radio Link Setup Response
NBAP NBAP
2. Radio Link Setup Request
RRC RRC
7. CCCH : RRC Connection Setup
Start RX description
Start TX description
4. ALCAP Iub Data Transport Bearer Setup
RRC RRC
9. DCCH : RRC Connection Setup Complete
DCH-FP DCH-FP 6. Uplink Synchronisation
NBAP NBAP
8. Radio Link Restore Indication
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NAS Signalling Connection Establishment
The NAS signalling connection between UE and CN can now be used for NAS message transfer
UE ServingRNC
CN
1. RRC Connection Establishment
RRCRRC2. DCCH : Initial Direct Transfer
RANAP RANAP3. Initial UE Message
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RAB Establish Flow(DCH-DCH, synchronous)
UE SRNCNodeB CN
RAB ASSIGNMENT REQUEST
ALCAP Establish
RL RECONFIG PRE
RL RECONFIG READY
ALCAP Establish, synchronization
RRC: RB SETUP
RRC: RB SETUP COMPLETERAB ASSIGNMENT RESPONSE
RL RECONFIG COMMIT
There are more than one ALCAP establish procedures on Iu Interface, more than one user plane RABs can be established simultaneously. After user plane establish, UE enters call connection.
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RAB Establish Flow(DCH-DCH, asynchronous)
UE SRNCNodeB CNRAB ASSIGNMENT REQUEST
ALCAP EstablishRL RECONFIG REQ
RL RECONFIG RESP
ALCAP Establish, synchronization
RRC: RB SETUP
RRC: RB SETUP COMPLETE
RAB ASSIGNMENT RESPONSE
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Transport Channel Reconfig Flow(Synchronised )
UE NodeB SRNC
RL RECONFIG PREPARE
RL RECONFIG READY
RL RECONFIG COMMIT
TRANSPORT CHANNEL RECONFIG
TRANSPORT CHANNEL RECONFIG COMPLETE
ALCAP Establish, synchronization
ALCAP Release
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Physical Channel Reconfig Flow
UE NodeB SRNC
RL RECONFIG PREPARE
RL RECONFIG READY
RL RECONFIG COMMIT
PHYSICAL CHANNEL RECONFIG
PHYSICAL CHANNEL RECONFIG COMPLETE
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RRC Release Flow( DCH)
UE NodeB SRNC CN
IU RELEASE COMMAND
IU RELEASE COMPLETE
ALCAP ReleaseRRC: RRC CONNECTION RELEASE
RRC: RRC CONNECTION RELEASE COMPLETE
RL DELETION
RL DELETION RESPONSE
ALCAP Release
Release procedure is usually originated by CN. But if UE is faulty, SRNC can also request release.
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Basic Signaling Procedures
2.1 Call overall process
2.2 Network start process
2.3 UE registration process
2.4 Call process
2.5 Connection mobility management process
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Soft HandoverSoft Handover
Macro diversity is a operation state in which a User
Equipment simultaneously has radio links with two or more
UTRAN access points. The aim is to improve quality of the
radio connection or provide seamless connection.
Active Set is a set of radio links simultaneously involved in a
specific communication service between an UE and a
UTRAN access point.
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Soft Handover Illustration (Intra RNC)
Before Soft Handover After Soft Handover
CN
SRNC
NodeBNodeB
CN
SRNC
NodeBNodeB
CN
SRNC
NodeBNodeB
During Soft Handover
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Soft Handover Illustration (Inter-RNC)
Before Soft Handover After Soft Handover
Radio Link(RL) is added and deleted simultaneously
CN
SRNC RNC
NodeB NodeBNodeB
CN
SRNC RNC
NodeB NodeBNodeB
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Soft Handover - Radio Link Addition
UE Node B
Drift RNS Drift RNC
Serving RNC
DCH-FP DCH-FP 8. Downlink Synchronisation
RNSAP RNSAP
1. Radio Link Setup Request
Start TX description
NBAP NBAP
2. Radio Link Setup
Request
RNSAP RNSAP
4. Radio Link Setup Response
NBAP NBAP
3. Radio Link Setup Response
Start RX description
Decision to setup new RL
RRC RRC
11. DCCH : Active Set Update Complete
RRC RRC
10. DCCH : Active Set Update
[Radio Link Addition]
ALCAP Iur Bearer Setup 5. ALCAP Iub Bearer Setup
DCH-FP DCH-FP 9. Uplink Synchronisation
RNSAP RNSAP
7. Radio Link Restore Indication
NBAP NBAP
6. Radio Link Restore Indication
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Soft Handover - Radio Link Deletion
UE Node BDrift RNS
DriftRNC
ServingRNC
RRCRRC2. DCCH : Active Set Update Complete
Decision to deleteold RL
RNSAP RNSAP
3. Radio Link DeletionRequest
NBAP NBAP
4. Radio Link DeletionRequest
RNSAP RNSAP
6. Radio Link DeletionResponse
NBAP NBAP
5. Radio Link DeletionResponse
Stop RX and TX
RRCRRC1. DCCH : Active Set Update
[Radio Link Deletion]
ALCAP Iur Bearer Release7. ALCAP Iub Bearer Release
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Hard Handover Illustration (Intra-RNC)
Before Har Handover 7 After Hard Handover
Radio Link(RL)cannot exist simultaneously
CN
SRNC
NodeBNodeB
CN
SRNC
NodeBNodeB
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Hard Handover Illustration (Inter-RNC)
Before Hard Handover After Hard Handover
Radio Link(RL)can’t exist simultaneously
CN
SRNC RNC
NodeBNodeB
CN
SRNC RNC
NodeBNodeB
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RNSAPRNSAP1. Radio Link Setup Request
UE Node B
Source
Node BTarget
RNCSource
RNCTarget
SRNC
RRCRRC
10. DCCH : Physical Channel Reconfiguration Complete
RRC7.DCCH : Physical Channel Reconfiguration
RRC
6. ALCAP Iur Data Transport Bearer Setup
NBAP NBAP2. Radio Link Setup Request
NBAP NBAP3. Radio Link Setup Response
NBAP NBAP12. Radio Link Deletion Request
NBAP NBAP13. Radio Link Deletion Response
4. ALCAP ub Data Transport Bearer Setup
14. ALCAP Iub Data Transport Bearer Release
RNSAP RNSAP15. Radio Link Deletion Response
16. ALCAP Iur Data Transport Bearer Release
RNSAP5. RL Setup Response
RNSAP
RNSAP11. Radio Link Deletion Request
RNSAP
NBAP NBAP8. Radio Link Failure Indication
RNSAPRNSAP
9. Radio Link Failure Indication
Hard Handover via Iur (DCH on Iur)Hard Handover via Iur (DCH on Iur)
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Hard Handover Flow( UMTS->GSM)
MAP/E MAP/E
2. PrepareHandover
BSSMAP BSSMAP4. Handover Request Ack
RANAP RANAP
13. Iu ReleaseComplete
BSSMAP BSSMAP
3. Handover Request
MAP/E MAP/E5. Prepare Handover
Response
RANAP RANAP
6. Relocation Command
BSSMAP BSSMAP
8. Handover Detect
BSSMAP BSSMAP
10. Handover Complete
MAP/E MAP/E
11. Send End Signal Request
MAP/E MAP/E
14. Send End Signal Response
RANAP RANAP1. Relocation Required
UE Node BRNC
Serving CN MSC BSC BTS
RRC
7. DCCH : Inter-System Handover Command
RRC
RR9. Handover Complete
RR
RANAP RANAP
12. Iu Release Command
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Forward Handover
Forward Handover, including CELL UPDATE and URA UPDATE, is
originated by UE. URA UPDATE procedure is only used for UE under
URA_PCH state to process URA reselection, and to check if RRC
connection is right.
For UE under CELL_FACH and CELL_PCH state
cell reselection needed
In specific SA(Service Area), Timer T305 timed out (this timer is defined in
system broadcast message)
For UE under CELL_PCH and URA_PCH state
transfer data on up link needed (enter CELL_FACH state)
upon receiving paging message on PCCH, originate cell update
CELL UPDATE process can be used to re-establish unrecoverable errors of
RLC entity( losing connection) , and to monitor RRC connection state.
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Cell Update with SRNS relocation
UE Source RNC
CN Target RNC
2. Uplink Signalling Transfer Indicatio n
[new C - RNTI, D - RNTI, UL message]
1. CCCH: Cell Update
[Cell Update Cause,U - RNTI, Measured results on PRACH]
RRC - relay RRC
RNSAP RNSAP
4. DCCH: Cell Update Confirm
[S - RNTI, SRNC - ID, new S - RNTI, new SRNC - ID, new C - RNTI]
RRC RRC
5. DCCH : UTRAN Mobility Information Confirm RRC
RRC
3. Serving RNC Relocation
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Cell Update via Iur without SRNS relocation
UE DRNC source
DRNC target
SRNC
RNSAP RNSAP 8. Common Transp. Channel Resources Release
RNSAP RNSAP 2. Uplink Signalling Transfer
Indication [new C-RNTI,D-RNTI,
UL message]
RNSAP
3. Common Transp. Channel Resources Initialization Request
RNSAP
RRC 1. CCCH: Cell Update
RRC-relay
RRC 6. DCCH: Cell Update Confirm RRC
RRC 7. DCCH: UTRAN Mobility Information Confirm
RRC
RNSAP RNSAP
4. Common Transp. Channel Resources Initialization Response
5. ALCAP Iur bearer setup
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Inter-RNS URA Update via Iur without SRNS relocation
UETargetRNC
5.CCCH: URA Update Confirm
SourceRNC
2.Uplink Signaling Transfer Indication
ServingRNC
[new C-RNTI,D-RNTI, UL message]
1.CCCH: URA Update
[U-RNTI, URA update cause]RRC-relayRRC
3. Decision Not toperform SRNS
relocation
RRC RRC-relay
RNSAP
RNSAP
4. Downlink Signaling Transfer Request
RNSAP
RNSAP
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Cell Reselection Flow( UMTS->GPRS)
UE CN
2. UE Access GPRS system
ServingRNC
RANAP RANAP
4. Iu Release Command
RANAP RANAP
4. Iu Release Complete
GPRS
1. UE releases connection with RNC
3. Inter-system information exchangedata transfer
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Cell reselection Flow( GPRS->UMTS)
UE ServingRNC
1. UE Access UMTS system(RNC)
CN
2. Make signaling connection with CN
3. User plane bearers set up
GPRS
4. Inter-system information exchangedata transfer
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