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

    Sketch of RRC State Transition

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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

    Sketch of RRC State Transition

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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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    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). 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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    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 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

    #510 Scrambling Code

    Group

    8160

    8161

    8175

    8160

    8161

    8175

    #504 Scrambling Code

    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-