UMTS (Universal Mobile Telecommunication System) · UMTS (Universal Mobile Telecommunication System) ... • control MSs roaming in an MSC assigned ... an exchange performing all

UMTS (Universal Mobile Telecommunication System)

• Network Architecture and Elements

• Protocol Architecture (packet switched domain)

• QoS Architecture

• Modes and States

• Important References

UMTS Networks 2Andreas Mitschele-Thiel 10-Dec-10

UMTS/GSM Network Architecture

GPRS Core(PacketSwitched)

SGSN

GGSN

Internet

GSMRAN

Base stationBase stationcontroller

Base station

Base station

UTRAN

Radio networkcontroller

node Bnode B

node B

MSC

PSTN

GSM Core (Circuit switched)

HLRAuCEIR

GMSC


UM

TS N

etw

ork

Arc

hite

ctur

eB

asic

Con

figur

atio

n, R

elea

se 3

BSS

BSC

RNS

RNC

CN

Node B Node B

A IuPS

Iur

Iub

Uu

MSC SGSN

Gs

GGSN GMSC

GnHLR

Gr

GcC

D

E

AuC H

EIR

F Gf

GiPSTN

IuCSGb

VLR B

Gp

VLR G

BTS BTS

Um

RNC

Abis

MSC

B

PSTNPSTN

cellSour

ce:

3GPP

23.

002-

3.4.

0

Circ

uit

switc

hed

CN Packet switched CN

GSM RAN

UTRAN


Logical Architecture of Packet-Switched Part

Source: 3GPP 23.060-3.8.0

Gf

Uu

Um

D

Gi

Gn

IuGc

CE

Gp

Gs

Signalling and Data Transfer Interface Signalling Interface

MSC/VLR

TE MT UTRAN TEPDN

(Packet Data Network)

GrIu

HLR

Other PLMN

SGSN

GGSN

Gd

SM-SC SMS-GMSC

SMS-IWMSC

GGSN

EIR SGSN

GnCGF

GaGa

BillingSystem

GbTE MT BSS

R

AR

CAMEL GSM-SCF

Ge AUC

H

GSM


Home Location Register (HLR)Home (primary) data base in charge of the management of mobile subscribersBasic information:• International Mobile Subscriber Identity (IMSI)• CS subscription information

– one or more Mobile Station International ISDN number(s) (MSISDN)• PS subscription information

– zero or more Packet Data Protocol (PDP) address(es)– permission for GGSN to dynamically allocate PDP addresses for a

subscriber• Location information enabling the charging and routing of calls towards

the MSC or SGSN where the MS is registered (e.g. VLR Number)

Authentication Centre (AuC)Stores data for each mobile subscriber

– to allow the International Mobile Subscriber Identity (IMSI) to be authenticated and

– to allow ciphered communication over the radio path The AuC communicates solely with its associated HLR (H-interface)


Visitor Location Register (VLR)(Secondary) data base supporting the management of mobilesubscribers currently located within its VLR area

Motivation: minimize load for HLR (i.e. of the primary data base)

Tasks:• control MSs roaming in an MSC assigned to it• exchange information with HLR to allow the proper handling of calls

Information maintained by VLR (for call handling):

– International Mobile Subscriber Identity (IMSI)– Mobile Station International ISDN number (MSISDN)– Mobile Station Roaming Number (MSRN)– Temporary Mobile Subscriber Identity (TMSI), if applicable– location area where the mobile station has been registered– the last known location and the initial location of the MS– supplementary service parameters attached to the mobile subscriber

(received from the HLR)


Mobile-services Switching Centre (MSC)

MSC: an exchange performing all the switching and signalling functions (CS only) for mobile stationsMSC controls mobile-originated and mobile-terminated CS calls

Functions– call management– mobility management (handling attach and authentication)– subscriber administration– CS data services (FAX, modem)– supplementary call services (call forwarding, etc.) – maintenance of charging data (for radio network usage)– SS7-based signaling transport

Main difference to an exchange in a fixed network: deal with mobility (e.g. location registration, handover)

Gateway MSC (GMSC)– Provides interconnection between the UMTS core network and external

PSTN/ISDN networks


GPRS Support Node (GSN) GSNs constitute the interface between the radio access network and the fixed networks for packet switched services (similar to MSC for CS calls)

Serving GSN (SGSN)

– session management– mobility management– subscriber database management (interface with HLR)– maintenance of charging data (for radio network usage)– IP-based transport of user data between SGSN and the UTRAN– IP- or SS7-based signaling transport

Gateway GSN (GGSN)

– gateway for UMTS packet service to external data networks (e.g. the Internet)

– IP interface towards SGSN– performs user data screening and security– maintenance of charging date (for external data network usage)


Radio Network Subsystem (RNS)Provide access to the UMTS terrestrial radio interface

RNS

RNC

RNS

RNC

Core Network

Node B Node B Node B Node B

Iu Iu

Iur

Iub IubIub Iub

UTRAN

Radio Network Controller (RNC)• (Radio) mobility management• Management of radio resources

Base Station (Node B)• Radio coverage of cells• Physical layer processing


Dedicated Channels – Soft and Softer Handover

RNS

RNC

RNS

RNC

Core Network


Iu Iu

Iur

Iub IubIub Iub

UTRAN

UE

SRNCDRNC

Softer handover: maximum ratio combiningin node B

Soft handover: radio frame selection (layer 1) in SRNC (and DRNC)


Shared Channels

RNS

RNC

RNS

RNC

Core Network


Iu Iu

Iur

Iub IubIub Iub

UTRAN

UE 1

SRNCDRNC

UE 2

shared channel

SRNC


Roles of Radio Network Controllers (RNCs)Serving RNC (SRNC)• A role an RNC can take with respect to a specific connection between an

UE and UTRAN• There is one Serving RNC for each UE that has a connection to UTRAN• The Serving RNC is in charge of the RRC connection between a UE and

the UTRAN• The Serving RNC terminates the Iu for this UE

Drift RNC (DRNC)

• A role an RNC can take with respect to a specific connection between a UE and UTRAN

• An RNC that supports the Serving RNC with radio resources when the connection between the UTRAN and the UE need to use cell(s) controlled by this RNC


Mobile Station (MS)

ITU-T Recommendyer UE

Mobile Equipment (ME) Mobile Termination (MT)

RTAF

Cu

Access Network

UuTerminal Equipment (TE)

USIM

Mobile Equipment (ME)radio transmission and application

Terminal Adaptation Functions (TAF)(service dependent)• mapping of terminal requests on

network capabilities• flow control/rate adaptations

Terminal Equipment (TE)supports for end-to-end application functions necessary for the operation of the access protocols by the user, e.g. a laptop

UMTS Subscriber Identity Module (USIM)user identitycontains data and procedures to unambiguously and securelyidentify itself

Mobile Termination (MT)functions for radio transmissionand management of the radio interface, e.g. the handset

Mobile station (MS)/User Equipment (UE)physical equipment used by a PLMN subscriber


MS-RNS/BSS-SGSN-GGSN – Control Plane

UDP

L2

L1

IP

L2

L1

IP

UDP

Gn or Gp

GSN GSN

GTP-C GTP-C

RLC

RRC

L1

GM M /SM / SM S

RRC

M AC

ATM

RANAP

AAL5

Relay

ATM

AAL5

3G SGSNRNSM SIu-PsUu

RLC SCCP

SignallingBearer

M AC

L1

SignallingBearer

RANAP

SCCP

GM M /SM / SM S

Protocol Architecture (PS Domain)


MS-RNS-SGSN – Control Plane

GMM (GPRS Mobility Management):– GMM supports mobility

management functionality such as attach, detach, security, and routing area update

SM (Session Management):

– SM supports PDP context activation and deactivation

SMS supports short message service

GTP-C (GPRS Tunneling Protocol for Control plane):– establish, manage and release of

GTP tunnels

Source: 3GPP 23.060-4.1.0

RANAP (Radio Access Network Application Protocol): – transport of higher-layer signalling– handling of signalling between the

3G-SGSN and UTRAN– management of the GTP connections

on the Iu interface

RRC (Radio Resource Control):

– Information Broadcast– RRC connection management

(setup, release, reconfiguration)– Radio Bearer management (setup,

release, reconfiguration)– Management of radio resources for

the RRC connection– RRC connection mobility functions– Paging/notification


User Plane Bearer Services – Overview

TE MT UTRAN CN IuEDGENODE

CNGateway

TE

UMTS

End-to-End Service

TE/MT LocalBearer Service

UMTS Bearer Service External BearerService

UMTS Bearer Service

Radio Access Bearer Service CN BearerService

BackboneBearer Service

Iu BearerService

Radio BearerService

UTRAFDD/TDD

Service

PhysicalBearer Service


Bearer Services – Analogy with Public Transportation

TE MT UTRAN CN IuEDGENODE

CNGateway

TE

UMTS

End-to-End Service

TE/MT LocalBearer Service

UMTS Bearer Service External BearerService

UMTS Bearer Service

Radio Access Bearer Service CN BearerService

BackboneBearer Service

Iu BearerService

Radio BearerService

UTRAFDD/TDD

Service

PhysicalBearer Service

cab: appartment to bus station

walk to cab

Bus: bus station to railway station

railway: station to station

combo ticket: cab and bus

combo ticket for rail, bus and cab:single ticket, single reservation, same service everywhere

cab with driver bus with driver

For each bearer: • specific attributes (delay,

bandwidth, guarantees, etc.• specific reservation

mechanism

train with driver, ...


MS-RNS/BSS-SGSN-GGSN – User Plane

L1

RLC

PDCP

MAC

E.g., IP,PPP

Application

L1

RLC

PDCP

MAC

ATM

UDP/IP

GTP-U

AAL5

Relay

L1

UDP/IP

L2

GTP-U

E.g., IP,PPP

3G-SGSNUTRANMSIu-PSUu Gn Gi

3G-GGSN

ATM

UDP/IP

GTP-U

AAL5

L1

UDP/IP

GTP-U

L2

Relay

Source: 3GPP 23.060-4.1.0


MS-RNS-SGSN-GGSN – User Plane

L1

RLC

PDCP

MAC

E.g., IP,PPP

Application

L1

RLC

PDCP

MAC

ATM

UDP/IP

GTP-U

AAL5

Relay

L1

UDP/IP

L2

GTP-U

E.g., IP,PPP


3G-GGSN

ATM

UDP/IP

GTP-U

AAL5

L1

UDP/IP

GTP-U

L2

Relay

GTP-U (GPRS Tunneling Protocol for User plane):• tunneling of user data between UTRAN and the SGSN• tunneling between the GSNs in the backbone network• encapsulation of all PDP PDUs

Source: 3GPP 23.060-4.1.0


MS-RNS-SGSN-GGSN – User Plane

L1

RLC

PDCP

MAC

E.g., IP,PPP

Application

L1

RLC

PDCP

MAC

ATM

UDP/IP

GTP-U

AAL5

Relay

L1

UDP/IP

L2

GTP-U

E.g., IP,PPP


3G-GGSN

ATM

UDP/IP

GTP-U

AAL5

L1

UDP/IP

GTP-U

L2

Relay

PDCP (Packet Data Convergence Protocol):

• provides protocol transparency (wrt the underlying radio-interface protocols) for higher-layer protocols

• support for e.g., IPv4, PPP and IPv6 (easy introduction of new higher-layer protocols)

• compression of control information(header compression)

Source: 3GPP 23.060-4.1.0


UMTS Protocol Architecture (packet switched)

Q2150.1

SGSNRNS

Control Plane User Plane Transport Plane Common

MM

SM

MAC

Phy-up

PHY

codec

RRC

RLC

PMM

SM

MAC

Phy-up

PHY

RRC

IP

PDCP

RLC

AAL5

RLC

MAC

RRC

AAL5

SSCF

SCCP

FP

SSCOP

MTP3-b

SSCF-N

SCCP

RANAP

RRC

ATM

STM-1

GTP-U

UDP

PDCP

IP

RLC

MAC

Phy-up

AAL5PHY SSCOP

MTP3B

AAL5

SSCF

Q2150.1

Q2150.1

Iu UP

ATM

E1

AAL2

SSCOP

MTP3B

AAL5

SSCF

SCCP

SM

MM

RANAP

SSCOP

MTP3-b

SSCF-N

SCCP

PMM

SM

ATM

STM-1

AAL5

IP

GTP-U GTP-C

UDP

L1

L2

SSCOP

MTP3B

AAL5

SSCF

Q2150.1

Q2150.1

IP

GTP-C

L1

GTP-U

UDP

L2

IP

GGSNUu Iups Gn


UMTS Protocol Architecture (packet switched):The complete picture

Q2150.1

SGSNRNCNode B

Control Plane User Plane Transport Plane Common

MM

SM

MAC

Phy-up

PHY

codec

RRC

RLC

PMM

SM

MAC

Phy-up

PHY

RRC

IP

PDCP

RLC

SSCOP

NBAP

AAL5

SSCOP

ALCAP

AAL5

SSCF SSCF FP

AAL2 AAL2 AAL5 AAL5

SSCF

RLC

MAC

Phy-up SCCP

FP

RRC

ATM

E1

NBAP

AAL5 AAL2

SSCOP

MTP3-b

SSCF-N

SCCP

RANAP

RRC

ATM

STM-1

GTP-U

UDP

PDCP

ALCAP

STC.2

SSCF-UNI

SSCOP

IP

RLC

MAC

Phy-up

FP

AAL5

ATM

E1

FP

AAL2

SSCOP

ALCAP

AAL5

SSCOP

NBAP

AAL5

SSCF SSCF

PHY

ATM

E1/ STM-1

AAL2 AAL5

NBAP

PHY

ALCAP

SSCOP

STC.2

SSCF-UNIFP

SSCOP

MTP3B

AAL5

SSCF

Q2150.1

Q2150.1

Iu UP

ATM

E1

AAL2

SSCOP

MTP3B

AAL5

SSCF

SCCP

SM

MM

RANAP

SSCOP

MTP3-b

SSCF-N

SCCP

PMM

SM

ATM

STM-1

AAL5

IP

GTP-U GTP-C

UDP

L1

L2

SSCOP

MTP3B

AAL5

SSCF

Q2150.1

Q2150.1

IP

GTP-C

L1

GTP-U

UDP

L2

IP

GGSNUu Iub Iups Gn


Rad

io P

roto

col A

rchi

tect

ure

L3

cont

rol

cont

rol

cont

rol

cont

rol

Logical Channel

Transport Channels

C-plane signalling U-plane information

PHY

L2/MAC

L1

RLC

DCNt GC

L2/RLC

MAC

RLC RLC

RLC RLC

RLC RLC

RLC

Duplication avoidance

UuS boundary

BMC L2/BMC

control

PDCPPDCP L2/PDCP

DCNt GC

Radio Bearers

RRC

Source: 3GPP 25.301-4.1.0

Radio Access BearersAS control plane SAPs


L3

cont

rol

cont

rol

cont

rol

cont

rol

Logical Channel

Transport Channels


PHY

L2/MAC

L1

RLC

DCNt GC

L2/RLC

MAC

RLC RLC

RLC RLC

RLC RLC

RLC


UuS boundary

BMC L2/BMC

control

PDCPPDCP L2/PDCP

DCNt GC

Radio Bearers

RRC

Radio Access BearersAS control plane SAPsPhysical Layer – Functions

• Macrodiversity distribution/combining and soft handover execution• Error detection on transport channels and indication to higher layers (CRC)• FEC encoding/decoding and interleaving/deinterleaving of transport channels• Multiplexing of transport channels and demultiplexing of coded composite

transport channels• Modulation and spreading/demodulation and despreading of physical channels• Frequency and time (chip, bit, slot, frame) synchronisation• Measurements and indication to higher layers (e.g. frame error rate, signal-to-

interference ratio, interference power, transmit power, etc.)• Power control• RF processing


L3

cont

rol

cont

rol

cont

rol

cont

rol

Logical Channel

Transport Channels


PHY

L2/MAC

L1

RLC

DCNt GC

L2/RLC

MAC

RLC RLC

RLC RLC

RLC RLC

RLC


UuS boundary

BMC L2/BMC

control

PDCPPDCP L2/PDCP

DCNt GC

Radio Bearers

RRC

Radio Access BearersAS control plane SAPsMedium Access Control (MAC) – Functions

• Mapping between logical channels and transport channels• Selection of appropriate Transport Format for each Transport Channel

depending on instantaneous source rate• Priority handling (multiplexing) between data flows of one UE (MAC-d)• Priority handling (scheduling) between different UEs (MAC-c/sh)• Identification of UEs on common transport channels• Multiplexing/demultiplexing of upper layer PDUs on transport channels• Traffic volume measurement• Transport channel type switching (controlled by RRC)• Ciphering for transparent RLC mode


L3

cont

rol

cont

rol

cont

rol

cont

rol

Logical Channel

Transport Channels


PHY

L2/MAC

L1

RLC

DCNt GC

L2/RLC

MAC

RLC RLC

RLC RLC

RLC RLC

RLC


UuS boundary

BMC L2/BMC

control

PDCPPDCP L2/PDCP

DCNt GC

Radio Bearers

RRC

Transport Services• Transparent data transfer (TM)

– segmentation/reassembly • Unacknowledged data transfer (UM)

– error detection• Acknowledged data transfer (AM)

– guaranteed delivery (error detection and correction)

Radio Link Control (RLC)


RLC – Functions

• Transfer of user data (AM, UM, TM)• Segmentation and reassembly (RLC PDU size adapted to transport

format)• Concatenation• Padding• Sequence number check (UM mode)• Duplicate RLC PDUs detection• In-sequence delivery of upper layer PDUs• Error correction (e.g. selective-repeat, go-back-n, stop-and-wait)

• Flow control between RLC peers• SDU discard• Protocol error detection and recovery• Exchange of status information between peer RLC entities• Ciphering (non-transparent mode)• Suspend/resume and stop/continue of data transfer• Re-establishment of AM/UM RLC entity

Convert variable-size higher layer PDUs into fixed-size

RLC PDUs (TBs)

Convert radio link errors into packet

loss and delay

Avoid Tx and Rx buffer overflows or

protocol stalling


L3

cont

rol

cont

rol

cont

rol

cont

rol

Logical Channel

Transport Channels


PHY

L2/MAC

L1

RLC

DCNt GC

L2/RLC

MAC

RLC RLC

RLC RLC

RLC RLC

RLC


UuS boundary

BMC L2/BMC

control

PDCPPDCP L2/PDCP

DCNt GC

Radio Bearers

RRC

Radio Resource Control (RRC)


RRC – Interaction with Lower Layers

R R C R R C

R L C R L C

Radio Resource Assignment [Code, Frequency, TS, TF Set, Mapping, etc.]

Measurement Report

RLC retransmission control

L 1 L 1

U T R A N U E

Con

trol

Mea

sure

men

ts

Con

trol

Mea

sure

men

ts

Con

trol

Mea

sure

men

ts

Con

trol

Mea

sure

men

ts

M A C M A C

Con

trol

Con

trol


RRC – Functions RRC handles the control plane signaling of layer 3 between the UEs and UTRAN:

- Broadcast of information provided by the non-access stratum (Core Network) - Broadcast of information related to the access stratum- Establishment, re-establishment, maintenance and release of RRC

connections- Establishment, reconfiguration and release of Radio Bearers- Assignment, reconfiguration and release of radio resources for the RRC

connection- RRC connection mobility functions- Paging/notification- Routing of higher layer PDUs- Control of requested QoS- UE measurement reporting and control of the reporting- Outer loop power control- Control of ciphering- Arbitration of radio resources on uplink DCH- Initial cell selection and reselection in idle mode- Integrity protection- Control of Cell Broadcast Service (CBS)


QoS ArchitectureBasics of QoSQoS attributes:

– data rate– error rate– delay– delay variation

How can the system ensure certain QoS attributes?– reservation of „dedicated“ resources for a connection (e.g. CS voice,

IntServ/RSVP)– differentiation of the use of a shared resource by a connection (e.g.

DiffServ)

Basic functions to provide QoS– admission control (possibly including resource reservation)– traffic classification– traffic conditioning (traffic shaping and policing)– scheduling– overload control


Bearer Services – Supported End User QoSSummary of applications in terms of requirements

Errortolerant

Errorintolerant

Conversational(delay <<1 sec)

Interactive(delay approx.1 sec)

Streaming(delay <10 sec)

Background(delay >10 sec)

Conversationalvoice and video Voice messaging Streaming audio

and video Fax

E-mail arrivalnotificationFTP, still image,

paging

E-commerce,WWW browsing,Telnet,

interactive gamesAcce

ptab

le e

rror

rat

e

Delays requirements


QoS Architecture (user plane)

ResourceManager

Mapper

Classif

Cond.

ResourceManager

ResourceManager

Mapper

ResourceManager

Mapper

ResourceManager

ResourceManager

Cond.

Classif

Cond.

MT GatewayCN EDGEUTRAN

BB network serviceIu network serviceUTRA phys. BS

data flow with indication of direction

TE Ext.Netw.

Local BS External BS

Classification function (Class.) assigns user data units received from the external bearer service to the appropriate UMTS bearer service according to the QoS requirements of each user data unit

Traffic conditioner (Cond.)

MT: provides conformance of the uplink user data traffic with the QoS attributes of the UMTS bearer service

Gateway: provide conformance of the downlink user data traffic with the QoS attributes of the UMTS bearer service

Mapping function marks each data unit with the specific QoS indication related to the bearer service performing the transfer of the data unit

Resource managers distribute its resources between all bearer services requesting transfer of data units on these resources (scheduling, etc. to provide QoS attributes) Sources: 3GPP TS 23.107-5.3.0, TR 23.907-1.2.0


QoS Architecture (control plane)

Transl. Transl.

Adm.Contr

RABManager

UMTS BSManager

UMTS BSManager

UMTS BSManager

Subscr.Control

Adm./Cap.Control


Ext.ServiceControl

LocalServiceControl

Iu BSManager

Radio BSManager

Iu NSManager

UTRAph. BS M

Radio BSManager

UTRAph. BS M

Local BSManager

Adm./Cap.Control

Adm./Cap.Control

Adm./Cap.Control

Iu BSManager

Iu NSManager

CN BSManager

Ext. BSManager

CN BSManager

service primitive interface

BB NSManager

BB NSManager

protocol interface

TE Ext.Netw.

Source: 3GPP TS 23.107-5.3.0, TR 23.907-1.2.0

QoS management functions for UMTS bearer service (control plane)

establishment and the modification of a UMTS bearer service signalling/negotiation with the UMTS external services establishment or modification of all UMTS internal services with the QoS


convertion between external service signalling and internal service primitives and attributes

Check if the network entity supports the requested service and the availability of required resourcesCheck if the network entity supports the requested service and the availability of required resources

QoS Architecture (control plane)convertion between external service signalling and internal service primitives and attributes

verification of administrative rights for using the service

signalling between each other and with external instances to establish or modify a UMTS bearer service and ext. services

translation of RAB service attributes into radio bearer service and Iu bearer service attributes

provision of bearer services with the required attributes

Transl. Transl.

Adm.Contr

RAB Manager

UMTS BS Manager

UMTS BS Manager

UMTS BS Manager

Subscr.Control

Adm./Cap.Control


Ext. Service Control

Local Service Control

Iu BS Manager

Radio BS Manager

Iu NS Manager

UTRA ph. BS M

Radio BS Manager

UTRA ph. BS M

Local BS Manager

Adm./Cap. Control

Adm./Cap.Control

Adm./Cap. Control

Iu BS Manager

Iu NS Manager

CN BS Manager

Ext. BS Manager

CN BS Manager

service primitive interfaceprotocol interface

BB NS Manager

BB NS Manager

TE Ext. Netw.


QoS ParametersUMTS Bearer Service Attributes (MT to GGSN)

– Traffic class [‘conversational’, ’streaming’, ’interactive’, ’background’]

– Maximum bitrate [kbps]

– Guaranteed bitrate [kbps]

– Delivery order [y/n]

– Maximum SDU size [bits]

– SDU format information [bits] (needed for efficient RLC TM operation)

– Error rate [erroneous SDUs, bit errors]

– Transfer delay [s]

– Traffic handling priority

– Allocation/Retention Priority

Similar QoS attributes are used for Radio Access Bearer


QoS Parameters

Traffic class Conversational class

Streaming class Interactive class Background class

Maximum bitrate X X X X

Delivery order X X X X

Maximum SDU size

X X

SDU format information

X X

Reliability X X X X

Transfer delay X X

Guaranteed bit rate

X X

Traffic handling priority

X

Allocation/Retention priority

X X X X

UMTS bearer attributes defined for each bearer class

Source: 3GPP TR 23.907-1.2.0


Mobility, Session and Radio Resource Management (PS mode)

UE mode

HLR GGSNSGSN

RNC

UE

RRC connection

Signaling connection

PMM state (detached, idle, connected)

SM: PDP context (active, inactive)


GPRS Mobility Management States

PM M-DET ACHED

PS Attach

PS S ignalling Connection R elease

PS S ignalling Connection Establish

PS Detach

PM M - CONNECTED PM M -IDLE

Detach, PS Attach Reject,RAU Reject

PM M-DET ACHED

PS Detach

PM M -CONNECTED

Serving RNCrelocation

3G -SG SN M M States M S M M States

S M-ACT IVE or INACT IVE




Detach, PS A ttach Reject,RAU Reject PS A ttach

PS S ignalling Connection Establish

PS S ignalling Connection R elease

PM M -IDLE

Source: 3GPP 23.060-4.1.0

Paging only(no signalingconnection between MSand SGSN)

Signalingconnectionbetween MS and SGSN(addressingby U-RNTI)

UMTS: PMM – Packet Mobility ManagementGSM: GMM – GPRS Mobility Management


Radio Link, RRC Connection, Signaling Connection

RNS

RNC

RNS

RNC

Core Network


Iu Iu

Iur

Iub IubIub Iub

UTRAN

UEradio link

RRC connection -> connected mode

signaling connection

SRNC

RRC connections and signaling connections are logical links


UE Modes and Mobility Management

Idle mode (no RRC connection; paging area is known; paging needed)– UE is identified by non-access stratum identities such as IMSI, TMSI

and P-TMSI. – UTRAN has no own information about the individual UEs in idle mode– UTRAN can only address e.g. all UEs in a cell or all UEs monitoring a

specific paging occasion

Connected mode (RRC connection, RNTI, cell or URA is known)– connected mode is entered when the RRC connection is established – RRC connection is established between UE and SRNC– UE is assigned a radio network temporary identity (U-RNTI and

possibly a C-RNTI) to be used as UE identity on common transport channels (RACH, FACH, PCH)

– connected mode does not require assignment of physical channel resources (cell_FACH or URA_PCH state)


Fundamental Difference Between CS and PS CommunicationConnection (e.g. voice, CS data) • clearly defined start and end • no burstiness

minutesconnection

setupconnection

release

Packet session (e.g. web surfing, fleet management, location services)• start and end times are typically unknown to the UMTS system• traffic is highly bursty

hours

seconds

Differences requires different solutions to• mobility mgmt and• communication mgmt


Session Management: States of PDP Context

A GPRS subscription contains the subscription of one or more PDP addresses

Each PDP address is described by one or more PDP contexts in the MS, SGSN, and GGSN

Each PDP context may be associated with a traffic flow template (TFT)

Every PDP context exists independently in one of two PDP states

The PDP state indicates whether data transfer is enabled for that PDP address and TFT or not

Reference: 3G 23.060, ch 9

GPRS subscription

PDP address(IP address)

PDP context(QoS attributes)

PDP stateinactive

PDP stateactive


Deactivate PDP Context or MM state change to IDLE

or PMM-DETACHED

Activate PDPContext

PDP ContextINACTIVE

PDP ContextACTIVE

Inactive state:– no valid routing or mapping

information to process data related to PDP address

-> no data transfer-> no updates due to location

changes (even in GPRS-attached state)

PDP context activation (transition to active state):– MS-initiated PDP context activation– network-requested PDP context

activation



Active state:– valid routing or mapping

information to process data related to PDP address (MS, SGSN, GGSN)

– requires PMM state PMM-idle or PMM-connected

-> data transfer possible-> updates due to location changes

PDP context deactivation:– PDP context deactivation procedure– MM state changes to PMM-

detached

PDP context modification, e.g. to modify QoS profile

Deactivate PDP Context or MM state change to IDLE

or PMM-DETACHED

Activate PDP Context

PDP ContextINACTIVE

PDP ContextACTIVE



Session Management: PDP Context and MM

Relation between MM and PDP states:

• All PDP contexts of a subscriber are associated with the same MM context for the IMSI of that subscriber

• The MM state is independent of the number and state of PDP contexts for the subscriber

• In both the PMM-IDLE and the PMM-CONNECTED states, session management may or may not have activated a PDP context

GPRS subscription

PDPaddress

PDPcontext

PDP stateinactive

PDP stateactive

PDPcontext

PDPcontext

PDPcontext

SingleMM context


LA

Location-related AreasLocation Area (LA)– area in which a mobile

station may move freely without updating the VLR

Routing Area (RA)– area in which a mobile

station, in PS mode, may move freely without updating the SGSN

– a RA is always contained within a location area

RA

RA

RA RA

RA

RA RA

RA

RA

LA/RAUpdate

RAUpdate

RAUpdate

RAUpdate

LA/RAUpdate

Source: 3GPP 23.002-5.5.0


UTRAN Registration Area – URA

LA

RA

RA

RA RA

RA

RA RA

RA

RA

URA

URAURA

URA URA

URA

URAURA

URA URA

URA

URAURA

URA URA

URA

URAURA

URA URA

URA

URAURA

URA URA

URA

URAURA

URA URA

URA

URAURA

URA URA

URA

URAURA

URA URA

URA

URAURA

URA URA

• URA is known to the UTRAN only

• URA is established in RRC connected mode

• URAs may overlap

URA

URAURA U

RA

URA

URA

URA

URA

URA

URA

URA


hours

seconds

Resource Management for Packet Data

cell_DCH

URA_PCH

cell_FACH

idle

fast release slow release


RRC States and Resource Consumption

cell_DCH

URA_PCH

cell_FACH

idle

T3

T2

T1

• no resource usage

• radio resources• channel codes• HW resources

• signaling resources

• RRC state machine exists as two peer entities, one in the MS and one in UTRAN (SRNC)

• Apart from transient situations and error cases the two peer entities are synchronized


Selection of Timeouts – Tradeoffs

cell_DCH

URA_PCH

cell_FACH

idle

T3

T2

T1

fast release

slow release

+ small fixed cost– lots of transitions– call setup delay

– large fixed cost+ few transitions+ small mean call

setup delay

Optimal timeouts depend on traffic model (duration of

pauses, traffic mix, mobility)

available resources (radio, code, HW)

call setup reqs.


ReferencesBooks:• Kaaranen, Ahtiainen, Laitinen, Naghian, Niemi: UMTS Networks –

Architecture, Mobility and Services. Wiley 2001• Walke, Althoff, Seidenberg: UMTS – Ein Kurs. J. Schlembach Fachverlag,

2001• Holma, Toskala: WCDMA for UMTS. Wiley, second edition, fall 2002

Central 3GPP Documents:• 21.101/21.102/21.103: List of standards for Release 3, 4 and 5,

respectively• 21.905: UMTS vocabulary and abbreviations • 23.002: UMTS network architecture (CN and AN entities) and procedures• 23.060: GPRS architecture• 25.401: UTRAN overview• 25.301: Radio link protocols (UTRA)• 25.931: UTRAN procedures