04 WO_BT05_E1_1 UMTS Signaling Flow-62

7/29/2019 04 WO_BT05_E1_1 UMTS Signaling Flow-62

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UMTS Signaling Flow

ZTE University


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Content

UE State transition

Signaling flow


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Classification of Flows

In terms of protocol stack, signaling flows can beaccess layer signaling flows or non-access layer

signaling flows.

In terms of network composition, signaling flows

can be categorized as circuit-switched or packet-switched.

Access layer and non-access layer signaling flows

are actually so named from the perspective ofprotocol stack.


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Classification of Flows

The flows at the access layer include PLMNselection, cell selection, and radio resource

management flows.

The radio resource management flows are the

flows at the RRC layer, including the RRCconnection setup flow, flow of the signaling setup

between UEs and CNs, RAB setup flow, call

release flow, handover flow, and SRNS redirection

flow.


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UE Working Modes

There are two basic working modes: Idle

UE stands by without any service. Theres no connection

between UE and UTRAN.

Connected UE transferred to the connected mode after accomplishing RRC

Connection Setup.

UE has 4 states under the connected mode:Cell-DCH, Cell-

FACH, Cell-PCH, URA-PCH


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UE State


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UE States Under the Connected Mode

Cell-DCH UE is activated, and in service using its dedicated

channels.

There are dedicated channels in both uplink and

downlink. UTRAN knows exactly which cell the UE is in.

Cell-FACH

UE is activated, but without too much data to transmit,

so theres no need to assign dedicated channels to it.

Downlink data transmitted in FACH, while uplink in

RACH.

UTRAN knows exactly which cell the UE is in.


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UE States Under the Connected Mode

Cell-PCH

There is no data transmitted in both uplink and downlink.

UE needs to listen to PICH for paging information.

UE works in discrete receiving, which saves the power effectively.

UTRAN knows exactly which cell the UE is in.

UE needs to do cell update procedure when it passes cells.

URA-PCH

There is no data transmitted in both uplink and downlink.

UE needs to listen to PICH for paging information and receive

discretely. UTRAN only knows which URA (UTRAN Registration Area) UE

exists.

UE updates its location information only when its URA changes,

which further reduces the signaling saves resource.


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RRC State Transition (I)

After RRC Connection Setup, UE will

transit to CELL_FACH or CELL_DCH.

CN indicates UE using dedicated

channel (CELL_DCH) or common

channel (CELL_FACH) according to

the service request.

If there is no service right now, UE

will be indicated into PCH mode orrelease RRC connection back to

IDLE mode.

URA_PCH

CELL_DCHCELL_FACH

CELL_PCH

IDLE

DEAD

IDLE

DEAD

CELL_DCHCELL_FACH

IDLE

Sketch of RRC State Transition

Transit from IDLE Mode


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URA_PCH

CELL_DCH

CELL_PCH

IDLE

DEAD

IDLE

DEAD

CELL_FACH

IDLE

RRC State Transition (II)

UE do not occupy dedicated

channels In the mode of

CELL_FACH.

UE receives downlink data through

FACH(S-CCPCH).

UE transmits uplink data through

RACH(PRACH).

Transit from CELL_FACH Mode



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URA_PCH

CELL_DCH CELL_FACH

CELL_PCH

IDLE

DEAD

IDLE

DEAD

CELL_DCH

IDLE

URA_PCH CELL_PCH

CELL_DCH

RRC State Transition (III)

UE transceives uplink and downlink

data through dedicated channels

(DPDCHs and DPCCHs).

During the time when there is no data

transmitted, CN may indicate UEs

transiting to URA_PCH or CELL_PCH.

Transit from CELL_DCH Mode



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URA_PCH

CELL_DCH CELL_FACH

CELL_PCH

IDLE

DEAD

IDLE

DEAD

CELL_DCH

IDLE

CELL_DCH

URA_PCH CELL_PCH

CELL_FACH

CELL_PCHURA_PCH

RRC State Transition (IV)

UE has no activated uplink.

Paging Information makes UE back to

CELL_FACH or CELL_DCH mode.

In CELL_PCH, UE should transit to

CELL_FACH first to finish cell updating,

and go back if no service request.

In URA_PCH, if URA changes, UE also

transits to CELL_FACH to finish cell

updating first before it goes back toURA_PCH.

System resource can be saved in these

two modes.Sketch of RRC State Transition


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Content

UE State transition

Signaling flow


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Basic Conception (1)

RRC (Radio Resource Control) provides information transfer service to the NAS (Non

Access Stratum).

responsible for controlling the configuration of UMTS

radio interface Layers 1 and 2. RRC Connection

A point to point bi directional connection between the

RRC (Radio Resource Control) entities on the UE (User

Equipment) and UTRAN (UMTS Terrestrial RadioAccess Network).

The UE requires an RRC connection to access the

services of the UMTS network.


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RAB -Radio Access Bearer Identify the service the AS (Access Stratum) provides to

the NAS (Non Access Stratum) for transfer of user data

between the UE (User Equipment) and the CN (Core

Network). RB -Radio Bearer

The service provided by the Layer 2 for the transfer of

user data between UE (User Equipment) and UTRAN

(UMTS Terrestrial Radio Access Network).


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RL (Radio Link) RL is a logical association between single UE (User

Equipment) and a single UTRAN (UMTS Terrestrial

Radio Access Network) access point.

Its physical realization comprises one or more radiobearer transmissions.

It is possible for a UMTS mobile to have many radio

links established, when this occurs the mobile is said to

be in a soft handover.


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Sketch of the basic conceptions


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UE Calling Flow

Power on

Cell selection

Location

Update

Idle Mode

RRC

Establish

NAS

Establish

Hand Over

Cell/

URA update

Channel

reconfiguration

RB/RAB

Modification

RAB

Establish

RRC

Release

Call

Initiate


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UE in Idle Mode


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What Information needed for UE?

1

Strongest cell2Slot boundary

3Frameboundary

4

Primary SC5 Information in broadcasts

channel


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1st Step: Cell Selection and Slot

Synchronization


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DL Scrambling Code Rule

218

-1 DL Scrambling Codes in total (0..262142)

The

left

8192

Scramblingcodes

are

used

for

compression

mode

The

left

8192

Scramblingcodes

are

used

for

compression

mode

#511 Scrambling Code

Group

8176

8177

8191

8176P-SC

8177S-SC

8191S-SC


Group

8160

8161

8175

8160

8161

8175


Group

8064

8065

8079

8064

8065

8079

#7 Scrambling Code

Group112

113

127

8176P-SC

8177S-SC

8191S-SC

#1 Scrambling Code

Group

1

6

17

3

1

16P-SC

17S-SC

31S-SC

#0 Scrambling Code

Group

0

1

1

5

0P-SC

1S-SC

15S-SC

#0 Scrambling Code Cluster

#63 Scrambling Code Cluster


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2rd Step: Frame synchronization and

Scrambling code-group


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Scrambling-code identification

CPICH is predefine

sequence

Spreading Factor is 256

(Cch,256,0

)

Scrambling by P-

scrambling code

UE identified through

symbol-by-symbol

correlation over the

primary P-CPICH with all

the scrambling codes

within the code group.


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Obtain broadcast information in P-CCPCH

P-CCPCH contain thecurrent SFN and system

broadcast information

P-CCPCH SF=256

(Cch,256,1

)

P-CCPCH scrambling by

primary scrambling code

UE can use obtained

primary scrambling code

to descrambling the P-

CCPCH and obtain the

BCH information


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UE Calling Flow

Power on

Cell selection

Location

Update

Idle Mode

RRC

Establish

NAS

Establish

Hand Over Cell/URA update

Channel

reconfiguration

RB/RAB

Modification

RAB

Establish

RRC

Release

Call

Initiate


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UE Initiate Random Access


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Establish Dedicated RRC Connection

UE Node B SRNC

2.Allocate RNTI

L1 and L2 Parameters

1. RRC Connection Request

5. ALCAP Establish and Synchronization

3. NBAP RL Setup Request

7. RRC Connection Setup Complete

6. RRC Connection Setup

4. NBAP RL Setup Response


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RRC Connection Rejection

If the RNC determines that the RRC connection cannot beestablished (for example, due to insufficient resources),

the RNC directly sends the UE an RRC CONNECTION

REJECT message which contains the reason for the

rejection of the RRC connection.


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1. RRC Initial Direct Transfer

Establish Signaling Link with CN

UE SRNC CN

3. SCCP CC(Success)

2. RANAP Initial UE Message

SCCP Connect Request

3. SCCP CJ(Failure)

4. RRC Direct Transfer

5. RRC Direct Transfer


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1.1 Send AuthenticationInfo

4. Security ModeCommand

5. Security ModeComplete

6. Security Mode Complete

3.Security Mode Control

Authentication and Security Mode

UE RNS MSC Server/VLR

1. Authentication Request

2. Authentication Response

HLR

2.1 Send AuthenticationInfo Ack


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CS Location Update Process

MAP Cancel LocationACK

MAP_Cancel_Location

Location UpdateRequest

MAP Update Location

MAP_Insert _Subscriber_Data

MAP_Update _Location_ACKLocation Update

Confirm ACK

TMSI_Allocation_Complete

UE RNS MSC Server/VLR PVLR HLR

MAP_Insert _Subscriber_Data_ACK

Release CN

Signaling ConnectionRelease RB

Establish RRC Connection

Establish CN Signaling Connection

Authentication and Security Mode


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UE Calling Flow

Power on

Cell selection

RRC

Establish

NAS

Establish

Hand OverCell/

URA update

Channel

reconfiguration

RB/RAB

Modification

RAB

Establish

RRC

Release

Call

Initiate

Location

Update

Idle Mode


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UE Work Mode Transforming

CELL_DCH CELL_FACH

CELL_PCHURA_PCH

IDLE

DEAD

RRC connection

All the Status exist in UTRAN and UE, and transparent for CN

Network

Selection (PLMN)

Cell Camping

Probe pagingchannel

Cell

Reselection

High level

Signaling

Triger (CN)

Dedicated

Channel

RB Transport

Service


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UE Calling Flow

Power on

Cell selection

Location

Update

Idle Mode

RRC

Establish

NAS

Establish

Hand Over

Cell/

URA update

Channel

reconfiguration

RB/RAB

Modification

RAB

Establish

RRC

Release

Call

Initiate


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Procedure of Call Initiate


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Call Setup Flow

CN initiates a paging message to RNC.

RNC judges the paging message from the CN and thensends a paging message to the corresponding UE.

If no RRC connection is available, UE will send a RRCconnection setup request message (RRC ConnectionRequest) to RNC.

RNC determines to set up a RRC connection according tothe service request and system resource occupation thensends a RRC connection setup message (RRCConnection Setup) to UE.

After signaling connection setup, the higher layer of UE(NAS) sends a service request message to CN through adirectly transfer message.

CN sends a RAB assignment message (RAB AssignmentRequest) to the RNC to allocate resource for UEs request.


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3. NBAP RL ReconfigurePrepare

RAB Establish Flow

UE Node B SRNC

1. RANAP RABAssignment Request

4. NBAP RL ReconfigureReady

MSC



6. NBAP RL ReconfigureCommit

7. RRC RB Setup

8. RRC RB Setup Complete

9. RANAP RABAssignment Response


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8. ISUP IAM

UE Initiate Call

UE RNS MSC Called MSC

1. RRC establish

6. RRC DT(Call Proceeding)

3. RRC DT(CM Service Request)

2. CN signaling establish

4. Authentication and Security

5. RRC DT(Setup)

7. RAB establish

10. ISUP ACM11. RRC DT(Alert)

12. ISUP ANM13. RRC DT(Connect)

14. RRC DT(Connect ACK)

15. Conversation

9. CN bearer establish


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UE Receiving Call

1. ISUP IAM

UE RNS Called MSC Calling MSC

4. RRC establish

8. RRC DT(Setup)

6. RRC DT(Paging Response)

5. CN signalling establish

7. Authentication and Security

9. RRC DT(Call Confirm)

10. RAB establish

2. Paging

3. Paging

11. RRC DT(Alerting)12. ISUP ACM

13. RRC DT(Connected)14. ISUP ANM

16. Conversation

15. RRC DT(Connect ACK)


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UE Calling Flow

Power on

Cell selection

Location

Update

Idle Mode

RRC

Establish

NAS

Establish

Hand Over

Cell/

URA update

Channel

reconfiguration

RB/RAB

Modification

RAB

Establish

RRC

Release

Call

Initiate


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Handover Category

Intra-system handover Softer handover, soft handover, hard handover

Depending on the Ec/No of CPICH

Inter-system handover

Between FDD and TDD

Handover with different system

2G/3G handover

Compression mode


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Softer/Soft Handover Gain and Costs

Softer/Soft Handover Gain: The optimal fast close loop power control (MS always keep connection

with the most powerful cell)

Seamless handover, without RB interruption

When MS moves to the edge of the cell, and could not obtain enoughsignal power, it can obtain Macro diversity from multiple cells

The UL signaling quality can be improved through obtaining Macro

diversity when Node B (Softer HO) and RNC (Soft HO) combine thereceiving signal and lower the required Transport power of UE.

Softer/Soft Handover Costs: Additional Rake receiver channel on Node B

Additional DL channelization code

Additional DL power

Additional Rake receiver channel on MS Additional transport link between Node B and RNC (RNC internal Soft

Handover)

Additional transport link between S-RNC and D-RNC (Soft handoverbetween RNCs)


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Soft Handover Flow

UE NodeB(DRNS) DRNCNodeB(SRNS)

Measurementreport

RL creation requestRL setup request

Active set update command

SRNC

RL setup response RL setup response

Active set update completionRL Deletion requestRL Deletion response

A

B


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Hard Handover Flow

UE TargetNodeB SRNCOriginalNodeBMeasurement report

RL setup request

Reconfiguration commandRL setup response

Reconfiguration completionRL deletion request

RL deletion response


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UE Calling Flow

Power on

Cell selection

Location

Update

Idle Mode

RRC

Establish

NAS

Establish

Hand Over

Cell/

URA update

Channel

reconfiguration

RB/RAB

Modification

RAB

Establish

RRC

Release

Call

Initiate


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SRNC Relocation

2. Relocation RequiredRANAP RANAP

RANAP RANAP

6. Relocation

Request Ack.

RANAP RANAP1. Relocation Required

UE Node B RNC

Source

RNC

Target

MSC/SGSN SGSN/MSC

RANAP RANAP

4. Relocation Request

RANAP RANAP3. Relocation Request

RANAP RANAP7. Relocation Request Ack.

RANAP RANAP9. Relocation Command

RANAP RANAP8. Relocation Command

RANAP RANAP

12. Relocation

Complete

RANAP RANAP11. Relocation Complete

RNSAP RNSAP

10. Relocation

Commit

RANAP

13. Iu Release Command

RANAP

RANAP14. Iu Release Command

RANAP

5. ALCAP Iu Data

Transport Bearer Setup

15. ALCAP Iu Data Transport Bearer Relelase

RANAP16. Iu Release Complete

RANAP

RANAP17. Iu Release Complete

RANAP


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UE Calling Flow

Power on

Cell selection

Location

Update

Idle Mode

RRC

Establish

NAS

Establish

Hand Over

Cell/

URA update

Channel

reconfiguration

RB/RAB

Modification

RAB

Establish

RRC

Release

Call

Initiate

DCH DCH Transport Channel


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DCH-DCH Transport Channel

ReconfigurationUE Node B

Drift RNS

Node B

Serving RNS

Drift

RNC

Serving

RNC

CN

RNSAP RNSAP

5. Radio Link Reconfiguration

Ready

RRCRRC13.DCCH: Transport Chann el Reconfiguration Complete

NBAPNBAP6. Radio Link Reconfiguration Ready

NBAPNBAP4. Radio Link Reconfiguration Ready

NBAPNBAP11. Radio Link Reconfiguration Commit

RNSAP RNSAP

9. Radio Link Reconfiguration

Commit

NBAPNBAP10. Radio Link Reconfiguration Commit

RRCRRC12.DCCH: Transport Channel Reconfiguration

8. ALCAP Iub Data Transport Bearer Set-up

RNSAP RNSAP1. Radio Link Reconfiguration

Prepare

NBAPNBAP2. Radio Link Reconfiguration Prepare

NBAPNBAP3. Radio Link Reconfiguration Prepare

ALCAP Iur Bearer Set-up7. ALCAP Iub Data Transport Bearer Set-up

15. ALCAP Iub Data Transport Bearer Release

ALCAP Iur Bearer Release14. ALCAP Iub Data Transport Bearer Release


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Cell-FACH to Cell-DCH State TransformUE Node B

Drift RNS

Drift

RNC

Serving

RNC

6. NodeB-SRNC Data Transport Bearer Sync.

RNSAP RNSAP

1. Radio Link Setup

Request

Start TX

NBAP NBAP

2. Radio Link Setup

Request

RNSAP RNSAP

4. Radio Link SetupResponse

NBAP NBAP

3. Radio Link Setup

Response

Start RX

Decision to switch to

Cell_DCH state

RRCRRC

8.DCCH: Physical Channel Reconfiguration Complete

RRCRRC

7.DCCH: Physical Channel Reconfiguration

ALCAP Iur Bearer Setup5. ALCAP Iub Bearer Setup

RNSAP RNSAP

9. Common Transp. Channel

Resources Release Request


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Cell-DCH to Cell-FACH TransformUE Node B DRNC SRNC

RNSAP6. Radio Link Deletion Request

RNSAP

RNSAPRNSAP9. Radio Link Deletion Response

3. ALCAP Iur bearer setup(if needed)

RRC4. DCCH : Physical Channel Reconfiguration

RRC

Cell_FACH

RRC5. DCCH : Phy sical Chan nel Reco nfig urati on Complete

RRC

NBAP7. Radio Link Deletion Request

NBAP

NBAPNBAP8. Radio Link Deletion Response

ur earer re ease

RNSAP

. ommon ransp. ann e esources

Initialization Request

RNSAP

RNSAPRNSAP

. ommon ransp. anne esources

Initialization Response

. u earer reease

- , r mary n o ,

op tion al: S econd ary C CPCH Info , PRACHInfo]


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UE Calling Flow

Power on

Cell selection

Location

Update

Idle Mode

RRC

Establish

NAS

Establish

Hand Over

Cell/

URA update

Channel

reconfiguration

RB/RAB

Modification

RAB

Establish

RRC

Release

Call

Initiate


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RAB Release Flow


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RRC Connection Release

UE NodeB SRNC

1. RRC RRC CONNECTION RELEASE

2. RRC RRC CONNECTION RELEASE COMPLETE

3. RL DELETION

4. RL DELETION RESPONSE

5. ALCAP 5. ALCAP Release


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Call setup flow (1)


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Call setup flow (2)


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Call setup flow (3)


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Call setup flow (4)


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Call setup flow (5)


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Call setup flow (6)


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04 WO_BT05_E1_1 UMTS Signaling Flow-62

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