3 UMTS Signaling Flow-62

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Transcript of 3 UMTS Signaling Flow-62

UMTS Signaling FlowZTE University

ContentUE State transition Signaling flow

Classification of Flows

In terms of protocol stack, signaling flows can be access layer signaling flows or non-access layer signaling flows. In terms of network composition, signaling flows can be categorized as circuit-switched or packetswitched. Access layer and non-access layer signaling flows are actually so named from the perspective of protocol stack.

Classification of Flows

The flows at the access layer include PLMN selection, cell selection, and radio resource management flows. The radio resource management flows are the flows at the RRC layer, including the RRC connection setup flow, flow of the signaling setup between UEs and CNs, RAB setup flow, call release flow, handover flow, and SRNS redirection flow.

UE Working Modes

There are two basic working modes:

Idle

UE stands by without any service. Theres no connection between UE and UTRAN. UE transferred to the connected mode after accomplishing RRC Connection Setup. UE has 4 states under the connected mode:Cell-DCH, CellFACH, Cell-PCH, URA-PCH

Connected

UE State

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 date 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.

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.

RRC State Transition (I) Transit from IDLE ModeURA_PCH CELL_PCH

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 or release RRC connection back to IDLE mode.

CELL_DCH

CELL_FACH

IDLE

DEAD

Sketch of RRC State Transition

RRC State Transition (II)Transit from CELL_FACH ModeURA_PCH CELL_PCH

CELL_DCH CELL_FACH

IDLE

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).

DEAD

Sketch of RRC State Transition

RRC State Transition (III)Transit from CELL_DCH ModeURA_PCH CELL_PCH

CELL_DCH

CELL_FACH

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.

IDLE

DEAD

Sketch of RRC State Transition

RRC State Transition (IV)CELL_PCHURA_PCHURA_PCH CELL_PCH

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 to URA_PCH. System resource can be saved in these two modes.

CELL_DCH

CELL_FACH

IDLE

DEAD

Sketch of RRC State Transition

ContentUE State transition Signaling flow

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. A point to point bi directional connection between the RRC (Radio Resource Control) entities on the UE (User Equipment) and UTRAN (UMTS Terrestrial Radio Access Network). The UE requires an RRC connection to access the services of the UMTS network.

RRC Connection

Basic Conception (2)

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). The service provided by the Layer 2 for the transfer of user data between UE (User Equipment) and UTRAN (UMTS Terrestrial Radio Access Network).

RB -Radio Bearer

Basic Conception (3)

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 radio bearer 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.

Sketch of the basic conceptions

UE Calling FlowPower on Cell selection

Hand Over

Cell/ URA update

Location

Channel reconfiguration

RB/RABModification

Update

Idle Mode

RRC Release

RAB Establish

Call Initiate

RRC Establish

NAS Establish

UE in Idle Mode

What Information needed for UE?

1 Strongest cell 4 Primary SC 2 Slot boundary 5 Information in broadcasts channel 3Frame boundary

1st Step: Cell Selection and Slot Synchronization

DL Scrambling Code Rule2 -1 DL Scrambling Codes in total (0..262142) #63 Scrambling Code Cluster18

The left 8176 8176P-SC Scrambling Code #7 8192 #510 Scrambling Code Group Scrambling 8177 8177S-SC Group codes 112 8176P-SC 8160 Scrambling Code #1 8160#504 Scrambling Code are 8191 8191S-SC 113 8177S-SC Group used 8161 8161Group for 16P-SC 1 #0 8064 8064 Scrambling Code compression 6 Group 127 8191S-SC 8175 17S-SC 81758065 8065 mode

#511 Scrambling Code #0 Scrambling Code Cluster Group

The left 8192 Scrambling codes are used for compression mode

1 0 0P-SC 7 31S-SC 1 8079 8079 1S-SC 3 1 15S-SC 1 5

2rd Step: Frame synchronization and Scrambling code-group

Scrambling-code identification

CPICH is predefine sequence Spreading Factor is 256 (Cch,256,0) Scrambling by Pscrambling code UE identified through symbol-by-symbol correlation over the primary P-CPICH with all the scrambling codes within the code group.

Obtain broadcast information in P-CCPCH

P-CCPCH contain the current 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 PCCPCH and obtain the BCH information

UE Calling FlowPower on Cell selection Hand Over Cell/ URA update

Location Channel reconfiguration RB/RAB Modification

Update

Idle Mode

RRC

RAB

Release

Establish

Call Initiate

RRC Establish

NAS Establish

UE Initiate Random Access

Establish Dedicated RRC ConnectionUE Node B1. RRC Connection Request2.Allocate RNTI L1 and L2 Parameters 3. NBAP RL Setup Request 4. NBAP RL Setup Response 5. ALCAP Establish and Synchronization 6. RRC Connection Setup

SRNC

7. RRC Connection Setup Complete

RRC Connection Rejection

If the RNC determines that the RRC connection cannot be established (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.

Establish Signaling Link with CNUE1. RRC Initial Direct Transfer

SRNC

CN

2. RANAP Initial UE MessageSCCP Connect Request 3. SCCP CC(Success) 3. SCCP CJ(Failure) 4. RRC Direct Transfer 5. RRC Direct Transfer

Authentication and Security ModeUE RNS1. Authentication Request 1.1 Send Authentication Info 2. Authentication Response 3.Security Mode Control 4. Security Mode Command 5. Security Mode Complete 2.1 Send Authentication Info Ack

MSC Server/VLR

HLR

6. Security Mode Complete

CS Location Update ProcessUE RNS MSC Server/VLR PVLR HLREstablish RRC Connection Establish CN Signaling Connection Location Update Request Authentication and Security Mode MAP Update Location MAP_Cancel_Location MAP Cancel Location ACK MAP_Insert _Subscriber_Data

MAP_Insert _Subscriber_Data_ACKLocation Update Confirm ACK MAP_Update _Location_ACK

TMSI_Allocation_CompleteRelease RB Release CN Signaling Connection

UE Calling FlowPower on Cell selection Hand Over Cell/ URA update

Location Channel reconfiguration RB/RAB Modification

Update

Idle Mode

RRC

RAB

Release

Establish

Call Initiate

RRC Establish

NAS Establish

UE Work Mode TransformingRRC connectionURA_PCH CELL_PCH

CELL_DCH

CELL_FACH

Dedicated Channel RB Transport Service

High level Signaling Triger (CN)

IDLEProbe paging channel Cell Reselection

Network Selection (PLMN) Cell Camping

DEAD

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

UE Calling FlowPower on Cell selection

Hand Over

Cell/ URA update

Location Update

Channel

RB/RAB Modificat