radioprinciples section3 utran scenario

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Section 3UTRAN scenarios

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Conversion into Alcatel-Lucent templateScholle, Martin2007-06-2003

RemarksAuthorDateEdition

Document History

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UTRAN scenarios 3 3

Objectives

z To be able to build the map of the radio channels(logical, transport and physical channels) from a white paper.

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UTRAN scenarios 3 4

Objectives [cont.]


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UTRAN scenarios 3 5

Table of Contents

z Introduction to UTRAN Scenariosz Introduction

z Radio Channels Mappingz Downlinkz Uplink

z Service Requestz System Information Collectionz RRC Connectionz IMSI Attachment & Location Updatez Paging

z RAB Establishmentz Admission Controlz Radio Bearer Establishment

z Mobility Management in Connected Modez Soft HO: Active & Monitoring Setz Soft HO: Eventsz Compressed Modez Hard HO: Events on other FDD

Frequenciesz Hard HO: Events on other GSM

Frequenciesz Exercises

z Scenario Descriptionz Downlinkz Uplink

Page

1 Introduction to UTRAN Scenarios 71.1 Introduction 8

2 Radio Channels Mapping 112.1 Downlink 122.2 Uplink 13

3 Service Request 143.1 System Information Collection 15

3.1.1 P-SCH & S-SCH 163.1.2 CPICH 173.1.3 System Information Broadcast 183.1.4 Procedure 203.1.5 Radio Channel Mapping: P-CCPCH 213.1.6 Cell Selection Principle 22

3.2 RRC Connection 233.2.1 UE Status 243.2.2 Procedure: RRC Connection Establishment 273.2.3 Procedure: RRC Connection: RRC Connection Release 283.2.4 How to contact UTRAN: the PRACH 29

3.3 IMSI Attachment & Location Update 313.3.1 Principles 323.3.2 Procedure: Direct Transfer 33

3.4 Paging 343.4.1 Procedure 1: UE in Connected Mode 353.4.2 Procedure 2: UE in Idle Mode 363.4.3 Paging: PICH & PCH Radio Channels 37

4 RAB Establishment 384.1 Admission Control 394.2 Radio Bearer Establishment 41

4.2.1 Signaling: RAB Establishment 424.2.2 Signaling: Radio Link Setup 434.2.3 Radio Bearer Mapping 444.2.4 Physical Layer Processing 454.2.5 Radio Channels 464.2.6 Radio Channels: Data Processing 474.2.7 Radio Channels: Transport Channel Multiplexing 484.2.8 Radio Channels: DPDCH/DPCCH Channels 49

5 Mobility Management in Connected Mode 505.1 Soft HO: Active & Monitoring Set 515.2 Soft HO: Events 525.3 Compressed Mode 535.4 Hard HO: Events on other FDD Frequencies 545.5 Hard HO: Events on other GSM Frequencies 55

6 Exercises 566.1 Scenario Description 576.2 Downlink 586.3 Uplink 59

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UTRAN scenarios 3 6

Table of Contents [cont.]

Switch to notes view!


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UTRAN scenarios 3 7

1 Introduction to UTRAN Scenarios

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UTRAN scenarios 3 8


1.1 Introduction

Iub

Serving RNC

CN Collection of System Information

System Information

RRC Connection

RRC Connection IMSI Attachment

IMSI Attachment

Paging

Paging

The UE is switched on !

How can it retrieve network parameters to request a service?

On the first part, we are going to see how a UE, after it is just switched on, can be able to request a service and to answer to a paging message.

So the first step is to retrieve information about the system. Thank to these system information the UE is able to attach its IMSI and to update its location to the Core Network.

After that the UE can monitor a channel to answer to a paging message or can request itself a service.

Section 3 Page 9



UTRAN scenarios 3 9


1.1 Introduction [cont.]

Iub

Serving RNC

CN

The UE requests a service.

How and in which conditions are the resources required setup ?

Admission Control

? RAB EstablishmentRAB

When a UE requests a service, the UTRAN must check if it has enough resources to establish new dedicated channels.

There are after signaling between the UE, the Node B, the RNC and the Core Network to provide to the UE the transfer of the data at the required QoS.

We will also how the data are mapped on the physical channels.

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UTRAN scenarios 3 10


1.1 Introduction [cont.]

Iub

Serving RNC

CN

The UE uses a service and moves !

How UTRAN can provide the service despite the mobility ?

A new radio link is added Hard Handover on another FDD carrier Inter RAT Handover

BSCBTS

UTRAN must provide the transfer of the data at the requested QoS to a moving user. So different kinds of handover have been defined.

The Soft Handover, the UE can be linked to several cells using the same fraquency.

The Hard Handover inter FDD carrier and the interRAT HandOver between the 3G and the 2G network if the user loses the 3G coverage.

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2 Radio Channels Mapping

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2.1 Downlink

Logical Ch.

Transport Ch.

Physical Ch.

AICHNot associated with transport channels PICH CPICH P-SCH S-SCH

PDSCH S-CCPCH P-CCPCHDPDCH + DPCCH

DTCH, DCCH CCCH, CTCH

DCH BCHPCHFACHDSCH

Not implemented yet in EvoliumTMSolution

PCCH BCCH

DPDCH and DPCCH multiplexed by time

Common Physical Ch.Dedicated Physical Ch.

Section 3 Page 13





2.2 Uplink

Logical Ch.

Transport Ch.

Physical Ch.

PRACH PCPCHDPDCH + DPCCH

DTCH, DCCH CCCH

DCH1 RACHDCH2

CCTrCH

CPCH

DPDCH and DPCCH multiplexed by modulation

DedicatedPhysical Ch.

CommonPhysical Ch.

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3 Service Request

Section 3 Page 15




3 Service Request

3.1 System Information Collection

PrinciplesThe UE synchronize itself at the slot on the P-SCH

UE synchronize itself at the frame level on the S-SCH and retrieve a group of 8 Scrambling codes.

The UE test the 8 SC on the CPICH to find the SC of the cell

The UE decode the BCH channel to read the system information

The UE select the best cell

Iub

Serving RNC

CN

???

Just after the switch on, the UE can decode only the P-SCH and S-SCH if it is on a covered area

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3.1.1 P-SCH & S-SCH

P-CCPCH Radio Frame 10 ms

Slot #0 Slot #1 Slot #14

acpP-SCH

S-SCH acs0

acp acpacs2 acs14

The SCH is time-multiplexed with the P-CCPCH (which carries the BCH) and consists of 2 sub-channels.

The Primary SCH (P-SCH) made of always the slot on all the FDD Cells. The UE uses it to acquire the slot synchronization to a cell.

The Secondary SCH (S-SCH) contains a sequence of 15 codes which identifies the Code Group of the Downlink Scrambling Code (DL SC) of the cell. The UE uses it to acquire the frame synchronization to a cell and to identify the Code Group of the DL SC.

256 chips

Cell Search Procedure (also called synchronization procedure)

z 3GPP TS 25.214 provides an informative description how it is typically done

z Step 1: slot synchronizationIn all the cell of any PLMN, the P-SCH is made of a unique & same primary code sequence of 256 chips repeated at each Time Slot Occurrence. This is typically done with a single matched filter (or any similar device) to the primary synchronisation code which is common to all cells. The slot timing of the cell can be obtained by detecting peaks in the matched filter output.

z Step 2: frame synchronization and code-group identificationA S-SCH is made of 15 repetitions of a secondary code sequence of 256 chips (one per Time Slot) transmitted in perfect synchronization with the P-SCH code sequences. The UTRAN uses 64 distinct secondary synchronization code sequences (reused in distant cells of the UTRAN). This is done by correlating the received signal with all possible secondary synchronisation code sequences, and identifying the maximum correlation value. Since the cyclic shifts of the sequences are unique the code group as well as the frame synchronisation is determined.

Each secondary code sequence corresponds to a unique group of 8 possible Primary Scrambling codes

z Step 3: (downlink) scrambling code identification} The UE determines the (primary) scrambling code used by the found cell through symbol-by-symbol

correlation over the CPICH (pilot) with all codes within the Code Group identified in the step 2 (8 possibilities).

} Afterwards the P-CCPCH can be detected and the system- and cell specific BCH information can be read.

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3.1.2 CPICH

CPICH (Common Pilot CHannel)

The pilot carries a pre-defined symbol sequence at a fixed rate.

It is a reference:

To aid the channel estimation at the terminal (time or phase reference)

To perform handover measurements and cell selection/reselection (power reference)

The UE tests the 8 DL SC of the Group Code. The DL SC which allows to retrieve the pre-define sequence is the DL SC of the cell.

Slot #0 Slot #1 Slot #14

Pre-defined symbol sequenceSF=256 Tslot=2560 chips 20 bits

The CPICH has the following characteristic

z The same channelization code is always used for the P-CPICH,z The P-CPICH is scrambled by the primary scrambling code,z There is one and only one P-CPICH per cell,z The P-CPICH is broadcast over the entire cell.

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3.1.3 System Information Broadcast

The broadcast system information:

May come from CN, RNC or Node-B.

Contains static parameters (Cell identity, supported PLMN types...) and dynamic parameters (UL interference level...).

Is arranged in System Information Blocks (SIB), which group together elements of the same nature.

Some exemple:SIB1: Core Network Information

SIB3: Cell Selection, Access Restriction

SIB7: UL Interference

SIB11: MeasurementCN

LA, RA

DL SC, Power Control info

UL interference level

Example of SIB:

z MIB: Master Info Block (structure & scheduling of SIBs)

z SIB 1: NAS System Information + Timer

z SIB 2: URA (not supported) +Timer

z SIB 3: Cell Selection/Reselection and Access Restriction

z SIB 5: Common channel Information (P-CCPCH, S-CCPCH, RACH) and AICH/PICH power offset

z SIB 7: UL Interference and PRACH parameter SIB 11:Measurements

z SIB 18:PLMN Identity of neighboring cells

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3.1.3 System Information Broadcast [cont.]

The broadcast system information can be carried on BCH which is transmitted permanently over the entire cell.

Transport Ch.

Logical Ch.

Physical Ch.

BCCH

BCH

P-CCPCH

The broadcast system information is made of 128 periodic radio frame. So its period is 1280 ms.

There are a Master SIB or MIB and several SIB (System Information Block) organised by domain.

Frame #0 Frame #1 Frame #2

Frame #i-1 Frame #i Frame #i+1

Frame #125 Frame #126 Frame #127

MIB SIB3 SIB11

SIB5 SIB7 MIB

SIB5SIB11 SIB7

Thanks to this channel, the UE is able to retrieve information allowing the request of a RRC connection like the Channelization code used on the uplink common channel

Three parameters are used to set the position of each SIB on the cycle.

SIB_POS: it is the position of the SIB on the cycle (#0 for the MIB for instance)

z SIB_REP: it is the repetition of the SIB on the cycle (the MIB is repeated several time on the cycle.z SIB_OFF: If one Radio Frame is not enough to send all the data for a SIB, the rest of the SIB can be send

on another radio frame. For example, 2 radio frame after the first one. It is the SIB_OFF.

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3.1.4 Procedure

System Information Update Request

Master/Segment Info Block(s), BCCH

modification time

Master/Segment Info Block(s)System Information (BCCH:BCH)

UE Node-B RNC

RRC RRC

NBAP

CN


RRC RRC


RRC RRC

System Information Update Response

NBAP NBAP

>> Why does RRC protocol >> Why does RRC protocol terminate at Nodeterminate at Node--B for B for

BCH (not at RNC)?BCH (not at RNC)?

NBAP

Section 3 Page 21





3.1.5 Radio Channel Mapping: P-CCPCH

The Primary CCPCH carries the BCH, which provides system- and cell-specific information (e.g set of uplink scrambling codes)

The P-CCPCH is a fixed rate 30 kbps DL physical channel, which provide a timing reference for all physical channels (directly for DL, indirectly for UL).CCPCH is scrambled under the Primary Scrambling code.

Slot #0 Slot #1 Slot #13 Slot #14Slot #i

SCH

Tslot=2560 chips

20 bits

256 chips

Payload of 18 bits

The P-CCPCH is time multiplexed with the SCH which is transmitted during the first 256 chips.

P-CCPCH timing is identical to that of SCH and CPICH (see 3GPP 25.211).

The P-CCPCH contains no layer 1 information.

Even if the PCCPCH is not transmitted during the 256 first chips of each slot (SCH), the scrambling code is aligned with the PCCPCH frame boundary, i.e the first complex chip of the PCCPCH frame is multiplied with chip number zero of the scrambling code.

The Secondary CCPCH, which is used to carry FACH and PCH information, is scrambled under the Primary scrambling code as well.

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3.1.6 Cell Selection Principle

Now, the UE can read the BCH of one cell.

But this cell is not necessary the best because the SCH has been chosen randomly.

The UE compares the cells to be camped on the best one.

There are 2 criterion:

QRxLev, from the CPICH RSCP, to estimate the reception level.

Qqual, from the CPICH Ec/No, to estimate the quality of reception. It takes in account the interference level.

When a UE is not connected, like here, and is moving, it has to reselect regularly the best cell for itself. To protect some cells, it is possible to facilitate or not the selection of one cell.

Iub

RNC

CN

???

Aim : find a suitable cell to be camped on

The Cell selection criterion is defined in 3GPP TS 25.304 as:

z Squal>0 with Squal=Qqualmeas - Qqualminz Srxlev>0 Srxlev= Qrxlevmeas Qrxlevmin - Pcompensation

Parameters :

z Qqualmeas: defines the quality of the cell} Measured CPICH Ec/N0

z Qqualmin: defines the threshold for the quality of the cell} Configurable in each cell independently

} Range: -24 dB to 0 dB (step 1 dB)

z Qrxlevmeas : defines the cell Rx Level value} Measured CPICH RSCP

z Qrxlevmin : defines the minimum required RX level of the cell} Configurable in each cell independently

} Range: -115 dBm to -25 dBm

z Pcompensation:} Parameter to take in account the UE capacity

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3 Service Request

3.2 RRC Connection

Why?The UE is switched on and has selected a cell.

The UE is in idle mode.

UTRAN doesnt know anything about this UE.

The UE has neither UTRAN identifier nor Scrambling and Channelization code.

The UE cant exchange any data with UTRAN.

To be known by UTRAN and to use dedicated radio resources, the UE has to be RRC connected.

After, the UE can attach its IMSI or update its location to the Core Network and can request a service

Iub

RNC

CN

RRC Connected

Section 3 Page 24




3.2 RRC Connection

3.2.1 UE Status

UE

detached

UE

in idle mode

UE

in connected

mode

RRC Connection Release

RRC Connection Establishment

out of coverage

just after switch on process

Including Cell search procedure

Just after the switch on, the UE has to attach its IMSI. Thanks to his procedure the Core Network knows, the UE is on the network and where it is located at the Location or routing area level.

Several sub-status in the connected

mode

To attach its IMSI and update its location the UE has to be in connected mode, so it has to request a RRC Connection

Just after switch on process contains:

z Cell selection (including cell search procedure) z PLMN selectionz Attachment procedure (see Appendix for more details)

The UE must enter the connected mode to transmit signalling or traffic data to the network

What is the relationship with the states of the mobile phone in GSM?

z The two GSM states, idle mode and connected mode, are similar to idle mode and cell_DCH state in UMTS.

What is the relationship with the states of the mobile phone in GPRS?

z There is no correspondence between GPRS states (idle, standby and ready) and UMTS states.

z Indeed there is no notion of connection on GPRS.

Section 3 Page 25




3.2 RRC Connection

3.2.1 UE Status [cont.]

Cell DCH

Cell FACH

URA PCH

Cell PCH

UE

in idle

mode

UE in connected mode

Cell_DCH state

Signalling and traffic data dedicated to the UE (mapped on DCCH and DTCH respectively) are carried on DCH transport channel

Cell_FACH state

Signalling and traffic data dedicated to the UE (mapped on DCCH and DTCH respectively) are carried on RACH (uplink) and FACH(downlink) transport channels

Cell_DCH Cell_FACHNo traffic UL/DL at expiry of timer

Cell_FACH Cell_DCHTraffic volume UL/DL too large

The initial state of the UE is determined by the DCCH established during RRC connection establishment:

z if the DCCH is mapped on a DCH, the UE is in cell_DCH statez if the DCCH is mapped on RACH/FACH, the UE is in cell_FACH state

The UE can move from one state to another during the time of the RRC connection.

z Transitions between states are: } based on traffic volume measurements and network load

} always triggered by UTRAN signalling

z Note: in cell_DCH state, the DSCH transport channel can also be used.

Section 3 Page 26




3.2 RRC Connection

3.2.1 UE Status [cont.]

Cell_PCH state

No transmission of signalling and traffic data dedicated to the UE (no DCCH and no DTCH)

But the RRC connection is still active (UTRAN keeps RNTI for UE) and UE location at a cell level.

- a DCCH (and possibly a DTCH) can be reestablished very quickly (this procedure is initiated by sending a paging signal PCH)

URA_PCH state

Very similar to cell_PCH state

UTRAN keeps the location of the UE at the URA level (set of UMTS cells)

Cell_PCH Cell_FACH URA_PCHToo many cell reselections

Cell_FACH Cell_PCHNo traffic UL/DL at expiry of timer 2

Cell/URA_PCH Cell_FACHIncoming DL or UL traffic

Cell DCH

Cell FACH

URA PCH

Cell PCH

UE

in idle

mode

UE in connected mode

URA: UTRAN Registration Area (a small set of cells)

Cell_PCH and URA_PCH states are needed for non real time services to optimise usage of codes and battery consumption. It would not be efficient to allocate permanently a DCH which would be used a very low percentage of time (Web application for example)

What is the difference between idle mode, Cell_PCH and URA_PCH states?

In idle mode the location of the UE is not known by the UTRAN, but only by the CN at a Location Area (LA) or Routing Area (RA) level (LA and RA and sets of cells larger than URA.

The paging message PCH must hence be sent in a LA or in a RA when the UE is in idle mode, whereas it only needs to be sent in a cell in Cell_PCH state or in an URA when the UE is in URA_PCH state (hence the paging procedure is much faster).

Section 3 Page 27




3.2 RRC Connection

3.2.2 Procedure: RRC Connection Establishment

Initial UE identity, Establishment cause, Initial UE capability

1. RRC Connection Request (CCCH:RACH)

UE

RRC RRC

3. Radio Link Establishment

Initial UE identity, RNTI, capability update requirement, TFS, TFCS, frequency, UL scrambling code, power control info

4. RRC Connection Setup (CCCH:FACH)RRC RRC

Integrity information, ciphering information

5. RRC Connection Setup Complete (DCCH:RACH or DCH)RRC RRC

2. Allocate RNTI, Select Level 1 and Level 2 parameters

(e.g. TFCS, scrambling code)

>> Can the UE send user information (e.g voice call) after compl>> Can the UE send user information (e.g voice call) after completing this stage?eting this stage?

Node-B RNC

1. UE initiates set-up of an RRC connection

z Initial UE identity: e.g TMSI z Establishment cause: e.g traffic class

2. RNC decides which transport channel to setup (RACH/FACH or DCH) and allocates

z RNTI (Radio Network Temporary Identity) and radio resources (e.g TFS, TFCS, scrambling codes) for this RRC connection.

3. A new radio link must be setup.

z This is done via a signalling procedure between RNC and Node-B which is managed by NBAP protocol (seeProcedure D for more detail).

4. Logical, transport and physical channel configuration are sent to the UE.

5. RRC Connection Setup Complete message is sent:

z on RACH in case of RRC connection on RACH/FACH (cell_FACH state)

z on DCH in case of RRC connection on DCH (cell_DCH state)

Section 3 Page 28




Node-B(DRNC)

SRNCDRNCNode-B(SRNC)

3.2 RRC Connection

3.2.3 Procedure: RRC Connection: RRC Connection Release

RRC RRC4. RRC Connection Release (DCCH:DCH )

Cause

RANAP RANAP

1. Iu Release Command

Cause

RANAP RANAP

2. Iu Release Complete

-

3. ALCAP Iu Bearer Release

RRC RRC5. RRC Connection Release Complete (DCCH:DCH )

-

6. Radio Link Deletion



UE CN

In this example, the UE is in macro-diversity on two Node-Bs from two different RNCs. Therefore the UE could only be in cell_DCH state (soft HO is only possible on DCH)

1. The CN initiates the release of RRC connection

2. -

3. SRNC initiates release of Iu Bearer using ALCAP protocol

4. -

5. -

6. SRNC initiates release of radio link (for Node-B of SRNC) using NBAP protocol

7. SRNC requires release of radio link (for Node-B of DRNC) to DRNC using RNSAP protocol

8. DRNC initiates release of radio link (for Node-B of DRNC) using NBAP protocol

Section 3 Page 29




3.2 RRC Connection

3.2.4 How to contact UTRAN: the PRACH

For the initial access, the UE has to use a common uplink channel called the PRACH

Every UE use this channel to request a connection. If 2 UEs request on the time there is collision, and UTRAN receives nothing.

To manage this problem, the UE sends a first message called preamble until it receives a response on a downlink channel called AICH.

After the response on the AICH, the UE sends its message (the request) on the PRACH.

Hello !

Iub

RNC

Preamble on the PRACH

Yes ! Response on the AICH

HELLO!I need a connection

Message part

PRACH= Physical Random Access Channel

AICH= Acquisition Indicator channel

Section 3 Page 30




3.2 RRC Connection

3.2.4 How to contact UTRAN: the PRACH [cont.]

The first preamble is sent with the power P.

The UE resends a preamble until it receives a response on the AICH.

At each time, it increases the power of the preamble by the Power Offset parameter (PO)

UTRAN cant receive its preamble if:

The power is not enough high

There is a collision with another user.

In the message part, there is the RRC connection request.

Preamble

Preamble

Message part

DPp,mPO

Reception of AICH

POP

PRACH channel

Section 3 Page 31




3 Service Request

3.3 IMSI Attachment & Location Update

HLR SGSNMSC/VLR

MSC/VLR SGSN

Iub

RNCThe UE has selected a cell.

It had to declared its identity and its location (LA & RA) to the Core Network.

So, it requests a RRC connection to send to the Core Network information about its situation.

The parameters are mainly the LA, the RA and its IMSI

Initial Attachment

In the selected PLMN, the UE:

z selects the best cell according to radio criteria I

z initiates attachment procedure on the selected cell

During the attachment procedure (called IMSI attach for CS domain, GPRS attach for PS domain), the UE indicates its presence to the PLMN for the purpose of using services:

z authentication procedure

z storage of subscriber data from the HLR in the VLR (or in the SGSN for PS domain)

z allocation of the TMSI (P-TMSI for PS domain)

The result of the procedure is notified to the UE:

z if successful, the UE can access services

z if it fails, the UE can only perform emergency calls

LA=Location Area= Set of cells for the CS CN

RA= Routinf Area= Set of cells for the PS CN

Section 3 Page 32





3.3.1 Principles

When camping on a cell, the terminal must register its LA and/or its RA.

When the terminal moves across the network, it must update its LA (RA) which is stored in VLR (SGSN) in the Core Network.

LA (RA) Update is performed periodically or when entering a new LA (RA).

HLRSGSNMSC/VLR

Location Area (LA)

Routing Area (RA)

MSC/VLR SGSN

LA and RA are managed on an independent way, but a RA must always be included in one LA (and not be divided into several different LAs).

z LA update is performed by the NAS layer MM (Mobility Management) located in UE and in MSC. z RA update is performed by NAS layer GMM (GPRS Mobility Management) located in UE and in SGSN.

In the Core Network, the location information is stored on databases:

z HLR (Home Location Register)} It stores the master copy of users service profile, which consists of information on allowed services,

forbidden roaming areas, and which is created when a new user subscribes to the system.

} The HLR also stores the serving system (MSC/VLR and/or SGSN) where the terminal is located.

z VLR (Visitor Location Register)} It serves the terminal in its current location for CS services and holds a copy of the visiting

} users service profile.

} It stores the Location Area (LA) where the terminal is located.

z SGSN (Serving GPRS Support Node)} It serves the terminal in its current location for PS services and holds a copy of the visiting

} users service profile.

} It stores Routing Area (RA) where the terminal is located.

Section 3 Page 33





3.3.2 Procedure: Direct Transfer

RANAP RANAP1. Direct Transfer

CN Domain Indicator, NAS PDU

RRC RRC

2. Downlink Direct Transfer (DCCH:FACH or DCH)

NAS message

UE Node-B SRNC CN

Use mainly for the IMSI attachment, location update and the authentification between the UE and the Core Network

RANAP RANAP2. Direct TransferCN Domain Indicator,

NAS PDU

RRC RRC

1. Uplink Direct Transfer (DCCH:RACH or DCH)

CN node indicator, NAS message

UE must be in cell_FACH or in cell_DCH states.

Section 3 Page 34




3 Service Request

3.4 Paging

Core Network

Called number

HLRMSC/VLR MSC/VLR

Location Area

Some one is calling me, I request a RRC

connection

Principle

Paging message with the IMSI of the

called UE

Iub

RNC

Iub

RNC

Iub

RNC

If the UE is in idle mode. UTRAN doesnt know them and can just forward the paging message coming from the Core Network to all the cell belonging to the Location ou Routing Area.

The UE monitors periodically a channel to check if it is paged or not.

If the UE is connected the Core Network knows the Serving RNC of the UE and sends the paging message just to this RNC.

The RNC knows the UE uses the dedicated or common channel to send the paging message.

Section 3 Page 35




3.4 Paging

3.4.1 Procedure 1: UE in Connected Mode

RANAP RANAP1. Paging

CN Domain Indicator, UE identity, Paging cause

RRC RRC2. Paging Type 2 (DCCH:FACH or DCH)

In this case the UE is already connected and is using a service (voice call, web-browsing ). The Core Network knows the situation of the UE and mainly its Serving RNC. The CN contacts directly the Serving RNC.

The RNC doesnt use the PCCH and the PCH but the channel used for the UE, dedicated or common, according to the status of the UE.

UE Node-B SRNC CN

UE is in cell_FACH or in cell_DCH states:

1. CN initiates the paging of a UE to Serving RNC

2. Paging of UE with Paging Type 2 (on DCCH) using the existing RRC connection

Section 3 Page 36




3.4 Paging

3.4.2 Procedure 2: UE in Idle Mode

RRC RRC2. Paging Type 1 (PCCH:PCH)

RRC RRC2. Paging Type1 (PCCH:PCH)


CN Domain Indicator, UE identity, Paging cause


Idem

When the is in idle mode, UTRAN doesnt know where it is located and the Core Network knows its location at the LA or RA level. UTRAN uses the PCCH and the PCH radio channels.

UE 1 Node-B1UE 2 Node-B2 RNC1 RNC2 CN

UE is in idle mode:

1. CN initiates the paging of a UE over a LA (RA in PS domain) spanning, for example, two RNCs.

2. Paging of UE with Paging Type 1

LA: Location Area, RA: Routing Area (see subchapter 5.8 Mobility Management)

A similar procedure applies to UE in cell_PCH or in URA_PCH states.

Section 3 Page 37




3.4 Paging

3.4.3 Paging: PICH & PCH Radio Channels

The UE doesnt watch the S-CCPCH.

It watches the PICH (Page Indicator Channel) at regular and defined interval and look for its PI, for Paging Indicator.

The PI is based on the IMSI. Several UEs can have the same PI.

When the UE find its PI on the PICH, it watches the S-CCPCH to check if it is for it and what is the cause.

Then it requests on RRC connection to have a RAB.

Transport Ch

Iub

RNC

PICHS-CCPCH

PCH

PCCH Logical Ch

Physical Ch

MAC

Physical layer

In RNC

In Node B

PICHS-CCPCH

Paging message

PI

PI

PI

...

The period of the cycle is between 4 and 4096 radio frames. That means the UE can monitor the PICH every X seconds, with X between 40 ms and 40,96 seconds. If the period is too short the UE uses too much power if the period is 40 s, the delay is really long.

It is a trade-off between the delay and the consumption.

To determine the radio frame number into the cycle and the Paging Indication, the UE uses its IMSI and others parameters send on the SIB.

Section 3 Page 38




4 RAB Establishment

Section 3 Page 39




4 RAB Establishment

4.1 Admission Control

According to the previous part WCDMA in UMTS, if the interference level at the Node B level is too high, the Node B cant decode all the signal. The size of the cell decreases. The interferences are due to several causes:

The radio environment and the load of the adjacent cells,

Some users use too much power, the power control manages this problem,

There are too many users on the the cells

UTRAN has to check if there is enough UL radio resource

Iub

RNC

f

P

ISCP = NoSIR

PG

Eb

RSCP = Ec

At Node B reception level

SIR too small to retrieve the message

2 others questions before adding a new user : Is there sufficient DL radio resource andsufficient processing resources ?

If the RAC has not been passed,

z For CS services, the call cant be established.z For PS services, the UTRAN may try assigning a RB with a lower bit rate. There are different level of bit

rates than can be used a given requested RAB. The Node B tries to assign first the highest, and then goes to the lower rates, as long as the RAC rejects the Radio Link Reconfiguration.

Section 3 Page 40




4 RAB Establishment

4.1 Admission Control [cont.]

Is there sufficient UL Radio Resource -> Rx RAC

If UL interference level + estimated new user contribution < threshold

Then Rx RAC ok

Is there sufficient DL Radio Resource -> Tx RAC

If Total DL Tx Power + estimated new user contribution < threshold

Then Tx RAC ok

Is there sufficient processing resource -> Processing RAC3 main points are checked:

the channelization codes

The DSP (in BBs) load

The number of user and radio links limited respectively to 64 users and 90 RLs

RAC = Radio Access Control

Section 3 Page 41




4 RAB Establishment

4.2 Radio Bearer Establishment

We have seen how a UE, after the switch on, can collect system information, update its location, request a RRC Connection and a service, can be paged and how UTRAN allows it to use services. Now how is established the RAB ?

Signaling

Core NetworkIub

Node B

RNC

UTRAN

RAB

Radio Bearer

Logical Channel

RLC

Transport Channel

MAC

Physical Channel

Phy.

RLC Mode: Tr., UM or AM and retransmission parameter for AM

TTI, TFS, TFCS, CRC, FEC, Coding Rate, Rate Matching

Frequency, Power, Channelization & Scrambling codes

RRC

Configured by

Iu Bearer RAB


Section 3 Page 42





4.2.1 Signaling: RAB Establishment

RANAP RANAP1. RAB Assignment Request

RAB parameters, User plane mode, Transport Address, Iu

Transport association

2. ALCAP Iu Data Transport Bearer Setup

3. Radio Link Establishment

RRC RRC4. RB Setup (DCCH:FACH or DCH )

TFS, TFCS...

RRC RRC5. RB Setup Complete (DCCH:RACH or DCH )

-

RANAP RANAP6. RAB Assignment Response

-

The UE is RRC connected and has requested a service.

UE Node-B SRNC CN

Can the UE send user information (e.g voice call) just after Radio Access Bearer establishment?

YES : At the end of this signaling procedure, a RAB has been assigned to the UE to carry user information. The RAB is mapped on the RB which has been set up. The RB is mapped on DTCH: RACH/FACH or DCH.

Section 3 Page 43





4.2.2 Signaling: Radio Link Setup

Cell id, TFS, TFCS, frequency, UL scrambling code, power control info

Radio Link Setup RequestNBAP NBAP

Signaling link termination, transport layer addressing info

Radio Link Setup ResponseNBAP NBAP

Downlink synchronisationIub-FP Iub-FP

Uplink synchronisationIub-FP Iub-FP

Start RX

Start TX

>> Are NBAP, ALCAP and RRC messages carried on the same transpor>> Are NBAP, ALCAP and RRC messages carried on the same transport bearers on Iub?t bearers on Iub?

ALCAP Iub Data Transport Bearer Setup

Node-B SRNC


This procedure is used in many RRC procedures, e.g RRC connection establishment (Procedure C1), Radio Bearer Set-up (Procedure F1), soft HO (Procedure G)

In this procedure:

z a radio link is set up by the RNC on the Node-B side using the NBAP protocol

z (a similar task is performed on the UE side using RRC protocol, see e.g. procedure C1)

z a terrestrial link (AAL2 bearer) is setup on Iub interface using ALCAP protocol

Section 3 Page 44





4.2.3 Radio Bearer Mapping

We have seen how a UE, after the switch on, can collect system information, update its location, request a RRC Connection and a service, can be paged and how UTRAN allows it to use services. Now how are established the RAB ?

Core NetworkIub

Node B

RNC

UTRAN

RAB

Radio Bearer

Logical Channel

RLC

Transport Channel

MAC

Physical Channel

Phy.

RLC Mode: Tr., UM or AM and retransmission parameter for AM

TTI, TFS, TFCS, CRC, FEC, Coding Rate, Rate Matching

Frequency, Power, Channelization & Scrambling codes

RRC

Configured by

Iu Bearer RAB


Section 3 Page 45





4.2.4 Physical Layer Processing

Convolutional coding, Turbo coding

10 ms frame duration15 time slots

CCtrCH

DPDCH, DPCCH, PRACH...

Channelization codesScrambling codes

QPSK

Channel Coding

Radio Frame Segmentation

Transport Channel Multiplexing

Physical Channel Mapping

Spreading

Modulation

Physical Channels spread over 5 MHz bandwidth

Layer 1

The physical layer belongs to control plane and to user plane.

Physical layer main functions:

z Multiplexing/de-multiplexing of transport channels on CCTrCH (Coded Composite Transport Channel) even if the transport channels require different QoS.

z Mapping of CCTrCH on physical channels

z Spreading/de-spreading and modulation/demodulation of physical channels

z RF processing (3 GPP 25.10x)

z Frequency and time (chip, bit, slot, frame) synchronization

z Measurements and indication to higher layers (e.g. FER, SIR, interference power, transmit power, etc.)

z Open loop and Inner loop power control

z Macro-diversity distribution/combining and soft handover execution

Section 3 Page 46





4.2.5 Radio Channels

Assuming a UE a video call service. What happens in Uplink ?

RLC

MAC

Physical Layer

Radio Bearer

Logical Ch. DTCH

Transport Ch. DCH

Physical Ch. DPDCH/DPCCH

RLC parameters

RAB :64 kbps

MAC parametersMode : Transparent because it is a real time service

CRC = 16 bits, FEC = Turbo Code Coding Rate = 1/3, TTI= 20 ms, TFS=(0*640, 2*640 bits)

640

640

640

640

640

640

TTI

How many radio frame are necessary to send all this data ?

CN

UE

The RB 20 (1st column ) corresponds to the Video Call.

Section 3 Page 47





4.2.6 Radio Channels: Data Processing

Assuming a UE a video call service. What happens in Uplink ?

#1 #2

#1 #2

Transport Blocks

CRC attachment

Tr Bl concatenation

Turbo coding (1/3)

Tail Bit Attachment

1 st interleaving

Radio Frame Segmentation

Rate matching

640 bits 16

(640+16)*2=1312 bits

1312*3=3936 bits

1312*3=3936 bits6

3942 bits

#1 #21971 1971

#1 #21971 +Nrm 1971 +Nrm

Can you deduce the SF ?

And the value of Nrm ?

First, the 16 CRC bits are added at each transport block.

Then the transport block are concatenated.

The turbo coding consist of adding a lot of redundant bits to be able to detect and correct errors.

Before the interleaving some bits are added. The purpose of the interleaving is to avoid to have big packet of errors at the reception.

Finally the data are segmented by 2, because the TTI=20 ms and a radio frame is 10 ms.

At the end to fill the radio frame, Nrm bits are added.

Section 3 Page 48





4.2.7 Radio Channels: Transport Channel Multiplexing

Assuming a UE a video call service and on the same time sends on a e-mail.

How can it be possible to send 2 different services on the same physical channel ?

Several transport channels can be time-coordinated to be multiplexed on a CCTrCHbefore mapping on one physical channel

MAC

TFC Selection

L1

TrCH Multiplexing

Phy. Ch. Mapping

CCTrCH

Physical Channel

DCH1 DCH2

Example:

TFS (DCH1)={(0*640); (4*640)}

TFS(DCH2)={(1*0); (1*39); (1*42); (1*55); (1*65)}

TFCS={(0*640); (1*0)}; {(0*640); (1*39)}; {(0*640); (1*42)}; {(0*640); (1*55)}; {(0*640); (1*65)}; {(1*640); (1*39)}; {(1*640); (1*42)}

MAC selects TFC inside TFCS.

There is one TFCS per CCTrCH

Transport Format

Transport Format Combination

TFS= Transport Format Set

TFCS=Transport Format Combination Set

TF=Transport Format

Section 3 Page 49





4.2.8 Radio Channels: DPDCH/DPCCH Channels

Uplink

Downlink



Data : user data, RRC Signaling & NAS Signaling DPDCH

DPCCH Pilot TFCI FBI TPC

Multiplexed by the modulation

Data1 TPC Data2 TFCI Pilot

DPDCH DPCCH DPDCH DPCCH DPCCH

Time-multiplexed

Why are DPDCH and DPCCH time-multiplexed in DL(and not transmitted simultaneously as in UL)?

Discontinuous transmission can cause audible interference to audio equipment close to the terminal (e.g hearing aids), which is a disturbance for user.

In UL the transmission is always continuous, because there is at least the DPCCH which is transmitted. The user will not be disturbed.

In DL the transmission may be discontinuous, but it is no problem (no user at the base station).

Note: The downlink DPDCH/DPCCH physical channels are called the DPCH physical channel.

Section 3 Page 50




5 Mobility Management in Connected Mode

Section 3 Page 51





5.1 Soft HO: Active & Monitoring Set

Iub

RNC

The RNC manages the Active Set and builds the Monitoring Set.

The Monitoring Set is built from the information of topology and design in the RNC.

The Active Set is managed from the event send by the UE to the RNC.

Cell in the Active Set

Cell in the Monitoring Set

The maximum number of cells in the monitoring set is 32.

The maximum number of cells in the active set is set from the Office Data, between 3 and 6.

The monitored set is built for each UE by the RNC from the neighboring list. The RNC selects the best cells in this list for the monitored cells.

Section 3 Page 52





5.2 Soft HO: Events

Iub

RNC

There are 3 events for the soft handover. The value measured is the CPICH Ec/No.

The event 1a is triggered when the CPICH Ec/No of a monitored cells is above a certain threshold.If the event is fulfilled the cell is added in the active set

The event 1b is triggered when the CPICH Ec/No of a active cell is below a certain threshold.If the event is fulfilled the cell is removed from the active set

The event 1c is triggered when the active set has reached its maximum size and the CPICH Ec/No of a monitored cells is better than a cell belonging to the active set.If the event is fulfilled the candidate cell replaces the cell in the active set Cell in the Active Set

Cell in the Monitoring Set

The simplified formula to trigger an 1a event is :

z 10log(Mnew) > 10log (MBest) R1a

Where:

z Mnew is a measurement on the candidate cell about the quality of reception.z Mbest is a measurement on the best cell in the active set about the quality of reception.z R1a is the Reporting Range.

Best Cell

T1 -> Event 1a

R1a

CPICH Ec/N0

TimeCandidate

Cell

T0

Section 3 Page 53





5.3 Compressed Mode

Iub

RNC


Cell in the Monitored Set, same FDD frequency

Cell in the Monitored Set, other FDD frequency

Cell in the Monitored Set, GSM cell

Most of the UEs are not dual receivers. And they need to perform measurements on other frequencies.

So UTRAN has to free it time window to perform these measurements on other FDD frequencies or on GSM frequencies.

The main method is to divide the SF of certain frame by 2, so it divides the length of the frame by 2.

Time interval to measure other frequencies

Compressed mode method available according to the 3GPP TS 25.212

z compressed mode methods:} By puncturing : the rate matching is applied for creating a transmission gap in one or two frames

(not in UL)

} Reducing the SF by 2

} Compressed frames can be obtained by higher layer scheduling. Higher layers then set restrictions so that only a subset of the allowed TFCs are used in a compressed frame. The maximum number of bits that will be delivered to the physical layer during the compressed radio frame is then known and a transmission gap can be generated

Section 3 Page 54





5.4 Hard HO: Events on other FDD Frequencies

Iub

RNC





There are 4 events to watch the UMTS cell with other FDD frequencies

The event 2d_cm is triggered when the quality of on the current frequency is below a certain quality. The compressed mode is launched.

The event 2b is triggered when the quality of the current frequency is belowa certain threshold and the quality on an other frequency is above a certain threshold

The event 2f is triggered when the quality on the current frequency is above a certain threshold. The compressed mode is deactivated.

Section 3 Page 55





5.5 Hard HO: Events on other GSM Frequencies

Iub

RNC





2 causes can trigger an hard HO toward the GSM system:

Some bad radio conditions

due to the service requested

The event 2d_cm is triggered when the quality of on the current frequency is below a certain quality. The compressed mode is launched.

The event 3a is triggered when the quality on the current FDD frequency is below a certain threshold and the quality on the GSM is above another threshold.

The event 3c is triggered when the service requested can be managed by the GSM, the voice typically.

Section 3 Page 56




6 Exercises

Section 3 Page 57




6 Exercises

6.1 Scenario Description

Objectives:Rebuilt the channels mapping, Logical, Transport and Physical channelsfrom a scenario to guide you with the 2 next pages

Scenario:

The UE switches on in a covered area

The UE collects information about the system

The UE requests a RRC connection to declare its location and releases the RRC connection

The UE receives a paging message to receive an e-mail

UTRAN establishes a RAB and is in the DCH_Cell State

As the traffic is not large, the UE passes to the FACH_Cell State

Be careful, following this scenario, some channels are missing.Which are the missing channels ?

Section 3 Page 58




6 Exercises

6.2 Downlink

Logical Ch.

Transport Ch.

Physical Ch.

Section 3 Page 59




6 Exercises

6.3 Uplink

Logical Ch.

Transport Ch.

Physical Ch.

Section 3 Page 60




Evaluation

Thank you for answeringthe objectives sheet

Objective: To be able to build the map of the radio channels (logical, transport and physical channels) from a white paper.

Section 3 Page 61




End of Module

radioprinciples section3 utran scenario

Documents

radio channelslogical

radio bearer mapping

radio channel mapping

pich pch radio channels

radio link setup

alcatellucent templatescholle

physical channels

dpdchdpcch channels