02. architecture protocols

7/25/2019 02. Architecture Protocols

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1 NOKIA topic: Warming Up/ July 2003 /Markus Wimmer

Course Content

Warming UP The Physical Layer

RRC Modes, System Information, Paging, & UpdateProcedure

Cell Selection & Reselection

RRC Connection Establishment WCDMA Measurements in the UE GSM Measurements for Inter-RAT Cell Reselection &

Handover Mobility Management and Connection Management UTRAN Control Protocol Overview (without RRC)


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Warming Up


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Objectives

At the end of this module, you will be able to Understand the RAB QoS parameters

Name the structure of UTRAN specific signalling interfaces


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This page was intentionally left empty.


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UMTS Release 99In December 1999, the first UMTS Release was frozen. This release is called nowadays UMTS Release 99. Inthe specification phase, two main objectives had to be met:

New radio interface solutionMobile communication became a big business case in the 90s of the last century with unexpected growthrates. In some areas, this imposed capacity problems. There were not enough radio resources available to

supply the subscribers in a satisfying way. The 2 nd generation mobile communication systems were stilloptimised for speech transmission. Also in the 90s, there was an unprecedented growth in datacommunications. This was mainly caused by the introduction of user friendly GUIs, the browsers, to serve inthe net, and by the steadily dropping costs for computer and router.Therefore, during the standardisation process, one major focus lay on the radio interface solution. It had to bemore efficient to serve more subscribers in one geographical area, resp. to allow higher data rates. On theother hand, more flexibly was required, too, so that all kinds of present and future multimedia applicationscould be served.CDMA was selected as multiple access technology for the radio interface solution. The UMTS radio interfacesolution is often called WCDMA, because cdma is used on 5 MHz. Two duplex transmission solutions areavailable with UMTS Release 99, one based on the TDD and one based on the FDD mode.The introduction of a new radio interface solution required a new design of the whole radio access network,which is called UTRAN.

CN evolutionThere are more than 400 GSM operators worldwide. So one requirement to UMTS Release 99 was to enable asmooth evolution from 2G to 3G. Therefore, the UMTS CN is nowadays an enhanced GSM NSS.


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UMTS Releases

UMTS Release 99

UMTS Release 4

UMTS Release 5

UMTS Release 6

UMTS CN = enhanced GSM NSS UTRAN & WCDMA

Bearer independent CS domain Low chip rate TDD mode UTRA repeater MMS LCS enhancements etc. IP Multimedia Subsystem (IMS) RNC connectivity to multiple CN nodes HSCSD

etc.

WLAN-3GPP feasibility study Network sharing feasibility study Security enhancements Push services etc.

19992001

2002

2003


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UMTS Release 99 Network ArchitectureThe UMTS CN can be organised into two main domains:

CS domainThis domain offers circuit switched bearer services. The cs domain is nowadays mainly usedfor real time data services, including speech and fax transmission. The network entities

MSC, GMSC and VLR can be found here.

PS domainThis domain offers packet switched bearer services. It is based on the GSM feature GPRS.Originally, this domain was developed for non-real time packet switched applications, suchas file transfer, email, access to the Internet. It is used today mainly for MMS. But there aretendencies to improve its offered QoS, so that real time services can be offered, too.The SGSN and GGSN are located in the packet switched domain. Other specified psdomain entities are the BGF and the CGF, which are often offered as stand alone devices.

There are also some network elements, which are shared by the packet switched andcircuit switched domain . The common network elements comprise the HLR, AuC and EIR.

A set of network elements were specified for application provisioning, which can be also foundin the CN. Examples are the Camel Service Environment and WAP. Some service solutionsaffect the access network, too. See for instance LCS.


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UMTS Release 99 Core NetworkCN (Core Network)

circuit switched (cs) domain

packet switched (ps) domain

commoncs & ps

networkelements

GERAN

UTRAN WAP

corporatenetworks

PDNIP-

backboneCGF

BillingCentre

BGF

Inter-PLMNNetwork

PSTN/ISDN

MSC/VLR GMSC

EIRHLR

AC

SGSN GGSN


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UMTS Release 99 Network ArchitectureThe UMTS Terrestrial Radio Access Network (UTRAN) is the access network, which was developed withUMTS. The access network is organised in Radio Network Subsystems (RNS). Each RNS has one

radio resource control unit, called Radio Network Controller (RNC). The tasks of a RNC can be seen onone figure on the following pages. In each RNS, there is at least one Node B active, which is connectedto its controlling RNC. A Node B is the 3G base station. One or several cells can be activated with oneNode B. The main features of a Node B can be seen on one figure of the following pages.

With UTRAN, four new interfaces were specified: Iu

Iu connects UTRAN with the CN. A distinguishing is drawn between the Iu connection to the ps domain,which is labelled Iu-PS, and to the cs domain, which is called Iu-CS. In both cases, ATM is used astransmission network solution. Please note, that there are differences in the protocol stacks on the Iu-

CS and Iu-PS interface. Iub

This interface is used between the Node B and its controlling RNC. Iur

This is an inter-RNS interface, connecting two neighbouring RNC. It is used among others in softhandover situations, where a UEs active cells are under the control of more than one RNC. One RNC isresponsible for the UE; it is called S-RNC. The remaining RNCs are called D-RNC.

UuUu is the acronym for the WCDMA radio interface.

On the interfaces Iu, Iur, and Iub, ATM is used for the transport of user data and higher layer signallinginformation.


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UTRAN

CN

circuitswitched

(cs)domain

packetswitched

(ps)domain

UTRAN

Radio Network Subsystem (RNS)

Radio Network Subsystem (RNS)

Iub

Iub

Iur

Iu-PS

Iu-CS

Uu

Uu

UE

UE

MSC/VLR

SGSN

RNC

RNC


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RNC Tasks and Functions

WCDMA radio resource management

incl. Radio resource management ofchannel configurations,traffic and control channels, handovers,power control.

Telecom functionalityincl. Location & connection management,ciphering, Iu and Iub channel management,ATM switching and multiplexing

Maintenance

incl. Fault localisation and reconfiguration Operation

incl. RNC and Node B parametermodification


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Node B Tasks and Functions

1 0 1 0 1 0 0 1 0 1 0 1 0 1 0 0 0 1 Iub Interface

ATM

Uu InterfaceWCDMA

Cellular Transmission managementManaging ATM switching and multiplexingover the Iub interface. Control of

AAL2/AAL5 connections. Control of thephysical transmission interfaces E1, PDH,

SDH or microwave.

Air Interface management .Controlling Uplink and Downlinkradio paths on the Uu Air

Interface. Baseband to RFconversion. Antenna multi-

coupling.

O&M Processing .Interfacing with NMS

and RNC for alarm andcontrol (Operations andMaintenance) functions.

Radio Channel functions .Logical to physical channel

mappings. Encoding/Decoding Spreading/Despreading user

traffic and signalling.

RNC


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Key WCDMA FactsTwo radio interface solutions were specified with UMTS Release 99: FDD mode (high chip rate) TDD modeThe used carrier frequency band is 5 MHz. The radio interface is organised in 10 ms frames,

which are divided into 15 timeslots. 72 10 ms frames represent one hyperframe, which was

introduced for UMTS-GSM Handovers. The information bearing stream is spreaded with theso-called spreading code. The spreading code consists of 3.84 Mchps. The spreading codeis a composition of two codes, the channelisation and the scrambling code. The scramblingcodes are derived from the Gold code family. They represent pseudo noise sequences. As aconsequence, if there is multipath propagation in the system, the individual multipaths canbe detected due the scrambling codes. There are 512 primary scrambling codes defined forthe downlink transmission. Uplink, several million scrambling codes are available. Ascrambling code repreats with every 10 ms frame. The channelisation code are used forchannel separation within one multipath. The channelisation codes are orthogonal codes.There repeat with each information bit, which has to be transmitted. Data rates andchannelisation codes are consequently related.Uplink, user data and control data are code multiplexed on one physical channel. Downlink,they are time multiplexed. The modulation is QPSK in UMTS Release 99.

Different types of handovers are supported: soft handover (FDD only) , softer handover (FDDonly), and hard handovers. Hand handovers can be classified into inter-frequency, inter-frequency, and inter-RAT handovers.


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Key WCDMA Facts

Duplex Transmission Modes: Frequency Division Duplex (FDD) Time Division Duplex (TDD)

Multiple Access: Code Division Multiple Access (CDMA)

Modulation (Rel. 99) Quadrature Phase Shift Keying (QPSK)

Bandwidth (Rel. 99) 5 MHz

Time Organisation: 10 ms per radio frame 15 time slots per frame 72 radio frames per hyperframe 2560 chips per timeslot

Spreading Spreading codes =

channelisation codes & scrambling codes Chip rate: 3.84 Mchips Channelisation codes = orthogonal codes,

length: depends on spreading factor Scrambling codes = pseudo noise codes

(derived from Gold code family)length: 38400 chips (10 ms)

Spreading Factors (FDD mode): UL: 4, 8, 16, 32, 64, 128, 256 DL: 4, 8, 16, 32, 64, 128, 256, 512The spreading factor can be changed every

TTI (10, 20, 40, or 80 ms).

Handover types: Soft & Softer HO (FDD only),Hard Handover;


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Access StratumStrata were introduced to group protocols related to one aspect of service. In this course,especially the Access Stratum is of importance. The Access Stratum comprises

infrastructure and protocols between entities of the infrastructure specific to the appliedaccess technique. In UMTS it offers services related to the data transmission via the radiointerface. It also allows the management of the radio interface on behalf of other parts of

the network. Two access strata are defined in UMTS: UTRAN MT

The protocols in use between UTRAN and the mobile phone specify in detail radiointerface related information. AS signalling is used to inform the UE about how to use theradio interface in the UL and DL direction.

UTRAN CNThe CN requests the access network to make transmission resources available. Theinteraction between UTRAN and the CN is hereby independent of the interaction betweenthe UTRAN and the UE. In other words, the UTRAN CN access stratum is independent ofthe used radio interface technology.

In this course, we focus our interest mainly on the transmission of signalling informationand related parameters via the radio interface. Consequently, the access stratum betweenthe UE and UTRAN will be discussed in detailed. But also NAS signalling will be outlined.NAS signalling is exchanged between the UE and the serving network. In this coursematerial, this signalling is regarded as part of the non-access stratum.


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AS and NAS Signalling

UTRAN

RNC

UE CN Iu edge node

NAS signalling and user datai.e. MM, PMM & CC, SS, SMS, SM

Access Stratum Signalling(Uu Stratum)

RRC

Access Stratum Signalling(Iu Stratum)

RANAP


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UMTS QoS ArchitectureWhen a subscriber requests a network service, he expects to get and is willing to pay for a

specific end-to-end quality of service. In a peer-to-peer communication, the QoS has to beprovided between the two participating terminals. The QoS of an end-to-end bearer service hasto be described. Parameter such as minimum bit rate, guaranteed bit rate, and end-to-end delaycan be used.

An end-to-end bearer service may be made available by several operators. This is the situationdisplayed in the figure on the right hand side. The UMTS provider offers the UMTS bearerservice, a service established between the UE and a CN edge node (GMSC, GGSN).

The UMTS bearer service and its QoS depends on the underlying bearer services: The CN bearerservice and the Radio Access Bearer (RAB) Service. The signalling protocols RANAP between

the CN Iu edge node (MSC/VLR, SGSN) and the RNC is used among others to establish,maintain, modify and release the Iu Bearer Service, which is required to establish the RABbetween the CN Iu edge node and the S-RNC. Between the S-RNC and the UE, the signallingand control protocol RRC is used to establish Radio Bearer (RB) Services, which is alsorequired to establish a RAB Service.

The RRC is used peer-to-peer between the UE and the S-RNC. There are two intermediatedevices, which also have to be informed about the bearer management: The Node B and during a soft handover the D-RNC. The management of the Iub resources to offer adequateQoS to higher layer bearer services is done with the NBAP. This protocol is also used toinform the Node B about the transmission and reception of common and dedicated informationon the radio interface Uu. The RNSAP is used between neighbouring RNCs for features suchas inter-RNC soft handovers and S-RNC relocation.


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QoS Management Functions in the Control Plane

TE ext.networkCN

GatewayMT UTRANCN Iu

edge node

UMTS BSManager

UMTS BSManager

UMTS BSManager

RABManager

CN BSMana-

ger

Iu BSMana-

ger

Ext. BSMana-

ger

CN BSMana-

ger

Iu BSMana-

ger

RadioBS

Mana-ger

RadioBS

Mana-ger

LocalBS

Mana-ger

BB NSMana-

ger

Iu NSMana-

ger

BB NSMana-

ger

Iu NSMana-

ger

UTRAph. BSMana-

ger

UTRAph. BSMana-

ger

SubscrControl

Adm/Cap.

Control

Adm/Cap.

Control

Trans-lation

Adm/Cap.

Control

Adm/Cap.

Control

Trans-lation

(adopted from TS 23.107)


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UMTS QoS ArchitectureIn UMTS, four QoS classes have been defined: Conversational class

is the QoS class for delay sensitive real time services such as speech telephony. Streaming class

is also regarded as real-time QoS class . It is also sensitive to delays ; it carries traffic, which

looks real time to a human user. An application for streaming class QoS is audiostreaming , where music files are downloaded to the receiver. There may be an interruption inthe transmission, which is not relevant for the user of the application, as long as there is stillenough data left in the buffer of the receiving equipment for seamless application provision togap the transmission time break.

Interactive classis a non-real time QoS class , i.e. it is used for applications with limited delay sensitivity(so-called interactive applications). But many applications in the internet still have timingconstraints, such as http, ftp, telnet, and smtp . A response to a request is expected within aspecific period of time. This is the QoS offered by the interactive class.

Background classis a non-real time QoS class for background applications, which are not delay sensitive .Example applications are email and file downloading .

A set of UMTS bearer attributes have been defined to specify the UMTS service . They arelisted on the right hand side. When a UMTS bearer is established, modified or released, aspectssuch as the UE capabilities, subscription profiles and network specific QoS profiles have to betaken under consideration.


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UMTS Bearer Attributes

Traffic class BackgroundclassInteractive

classStreaming

classConversational

class

Maximum bit rate

SDU formatinformation

SDU error ratio

Residual biterror ratioDelivery of

erroneous SDUsTransfer delay

Guaranteed bit rateTraffic handling

priorityAllocation/Retention

priority

Delivery orderMaximum SDU size

(adopted from TS 23.107 chap. 6.4.3.3)


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UTRAN Specific Signalling and Control Protocols

3G-MSC/VLR

3G-SGSN

UE Node BRNC

RNC

RNS

RNS

RRC

Iur: RNSAP

I u - P S : R A N A P

I u - C S : RA N A P

I u b : N B A P

TS 25.331TS 25.331

TS 25.433TS 25.433

TS 25.423TS 25.423

TS 25.413TS 25.413

TS 25.413TS 25.413


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General Protocol Model for UTRAN InterfacesThe general protocol model for UTRAN interfaces can be seen in the figure on the right handside. It is organised in horizontal and vertical planes.

There are two main vertical layers:

The control plane is used for signalling and control. UTRAN specific signalling protocols hadbeen developed, such as the RNSAP. This is one example of an application protocol, asdenoted in the figure. Each signalling and control protocol requires a signalling bearer. Thesignalling bearers in UMTS are based on standard bearer protocols (e.g. ATM).

The user plane describes the user data transport. The data streams are transmitted via databearers.

Within the transport network layers, there are vertical transport network user and controlplanes. A transport network control plane is responsible for the transport of higher layer data.The transmission resources for the control plane are made available by operation andmaintenance. The Transmission resources for the user data streams can be made availableon demand. On some interface, ALCAP is used. It is a transport network control planespecific signalling protocol to establish, maintain, modify, and release data bearers. It is forinstance in use on the Iu-CS interface, but not on the Iu-PS interface. The signalling bearersfor ALCAP are always set up by operations and maintenance.


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Physical Layer

General Protocol Model for UTRAN Interfaces(copied from TS 25.401 chap. 11.1.1)

Control Plane User PlaneRadioNetworkLayer

TransportNetworkLayer

ApplicationProtocol

Signalling

Bearer(s)

Signalling

Bearer(s)

Data

Bearer(s)

ALCAP

DataStreams

Transport NetworkControl Plane User Plane

Transport NetworkUser Plane

Transport Network


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General Protocol Model for UTRAN InterfacesThe figure on the right hand side shows the Uu access stratum protocols as implemented inthe UE. The UE protocol stack can be divided into a control and a user plane. The L3

protocol RRC is used to inform the UE about the use of the uplink and downlink radioresources. The RRC protocols peer entities are the RNC and the Node B. The receivingentity has to configure the MAC, PHY, PDCP, and BMC protocol entities in accordance to

the received commands.

The protocol stacks for signalling and user data transfer can be seen with the two figures,which follow the next one.


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MAC Layer

RLC Layer

PHY Layer

Radio Interface Protocol Architecture (in UE)(copied from TS 25.301 chap. 5.1)

Control Plane Signalling User Plane Signalling

RRC Layer

TrCHs

RLCRLCRLC

RLC

RLC RLCRLC

RLC

BMC

PDCPPDCP

PDCP

PhyCHs

LogCHs

RBs

controlcontrol

control

control

control


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ReferencesFor this course module, following ETSI specifications were used:

TS 23.002 V3.05.0 TS 23.101 V3.10.0 TS 24.410 V3.08.0

TS 25.301 V3.11.0 TS 25.401 V3.10.0


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GSM & UMTS Evolution

1990/91 1994 97 98 1999/2000 01 year

Phase 1Tele & Bearer

ServicesFR speech

SMSData 9.6 kbps

Phase 2

SupplementaryServices

HR speech

96 97 98 99

99

Phase 2+

HSCSD, GPRS & EDGE PS Domain New Services

IN-applications EFR & AMR .

Annual ReleaseR4 R5 R6 R7

99 02 04 06

WCDMA

UTRAN VHE .

ATM CN TD-SCDMA

IMS HSDPA IP UTRAN

EUDCH new services

e.g. PoC, MBMS W-AMR

MIMO WLAN

Integration GSM

UMTS

4G

2010?

2G2.5G

3G3.5G

4


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Radio Protocol Architecture

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Channel Configuration Scenario

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02. architecture protocols

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