Nokia 3G UTRAN

1 © NOKIA topic: Warming Up/ July 2003 /Markus Wimmer
Course Content
• Warming UP
• The Physical Layer
• RRC Modes, System Information, Paging, & Update
Procedure
• 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)

Warming Up

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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UMTS Release 99
In December 1999, the first UMTS Release was frozen. This release is called nowadays UMTS Release 99. In
the specification phase, two main objectives had to be met:
• New radio interface solution
Mobile communication became a big business case in the 90s of the last century with unexpected growth
rates. In some areas, this imposed capacity problems. There were not enough radio resources available to
supply the subscribers in a satisfying way. The 2nd
generation mobile communication systems were still
optimised for speech transmission. Also in the 90s, there was an unprecedented growth in data
communications. This was mainly caused by the introduction of user friendly GUIs, the browsers, to serve in
the 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 be
more efficient to serve more subscribers in one geographical area, resp. to allow higher data rates. On the
other hand, more flexibly was required, too, so that all kinds of present and future multimedia applications
could be served.
CDMA was selected as multiple access technology for the radio interface solution. The UMTS radio interface
solution is often called WCDMA, because cdma is used on 5 MHz. Two duplex transmission solutions are
available 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 evolution
There are more than 400 GSM operators worldwide. So one requirement to UMTS Release 99 was to enable a
smooth evolution from 2G to 3G. Therefore, the UMTS CN is nowadays an enhanced GSM NSS.

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.
1999
2001
2002
2003

UMTS Release 99 Network Architecture
The UMTS CN can be organised into two main domains:
• CS domain
This domain offers circuit switched bearer services. The cs domain is nowadays mainly used
for real time data services, including speech and fax transmission. The network entities
MSC, GMSC and VLR can be found here.
• PS domain
This 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, such
as file transfer, email, access to the Internet. It is used today mainly for MMS. But there are
tendencies 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 ps
domain 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 and
circuit 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 found
in the CN. Examples are the Camel Service Environment and WAP. Some service solutions
affect the access network, too. See for instance LCS.

UMTS Release 99 Core Network
CN (Core Network)
circuit switched (cs) domain
packet switched (ps) domain
common
cs & ps
network
elements
GERAN
UTRAN
WAP
corporate
networks
PDNIP-
backbone
CGF
Billing
Centre
BGF
Inter-PLMN
Network
PSTN/
ISDN
MSC/VLR GMSC
EIR
HLR
AC
SGSN GGSN

UMTS Release 99 Network Architecture
The UMTS Terrestrial Radio Access Network (UTRAN) is the access network, which was developed with
UMTS. 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 on
one figure on the following pages. In each RNS, there is at least one Node B active, which is connected
to its controlling RNC. A Node B is the 3G base station. One or several cells can be activated with one
Node 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 as
transmission 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 soft
handover situations, where a UE‘s active cells are under the control of more than one RNC. One RNC is
responsible for the UE; it is called S-RNC. The remaining RNCs are called D-RNC.
• Uu
Uu 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 signalling
information.

UTRAN
CN
circuit
switched
(cs)
domain
packet
switched
(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

RNC Tasks and Functions
• WCDMA radio resource management
incl. Radio resource management of
channel configurations,
traffic and control channels, handovers,
power control.
• Telecom functionality
incl. 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 parameter
modification

Node B Tasks and Functions
101010010101010001Iub Interface
ATM
Uu Interface
WCDMA
Cellular Transmission management
Managing ATM switching and multiplexing
over the Iub interface. Control of
AAL2/AAL5 connections. Control of the
physical transmission interfaces – E1, PDH,
SDH or microwave.
Air Interface management.
Controlling Uplink and Downlink
radio paths on the Uu Air
Interface. Baseband to RF
conversion. Antenna multi-
coupling.
O&M Processing.
Interfacing with NMS
and RNC for alarm and
control (Operations and
Maintenance) functions.
Radio Channel functions.
Logical to physical channel
mappings. Encoding/Decoding –
Spreading/Despreading user
traffic and signalling.
RNC

Key WCDMA Facts
Two radio interface solutions were specified with UMTS Release 99:
• FDD mode
• (high chip rate) TDD mode
The 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 the
so-called spreading code. The spreading code consists of 3.84 Mchps. The spreading code
is a composition of two codes, the channelisation and the scrambling code. The scrambling
codes are derived from the Gold code family. They represent pseudo noise sequences. As a
consequence, if there is multipath propagation in the system, the individual multipaths can
be detected due the scrambling codes. There are 512 primary scrambling codes defined for
the downlink transmission. Uplink, several million scrambling codes are available. A
scrambling code repreats with every 10 ms frame. The channelisation code are used for
channel separation within one multipath. The channelisation codes are orthogonal codes.
There repeat with each information bit, which has to be transmitted. Data rates and
channelisation 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 (FDD
only), and hard handovers. Hand handovers can be classified into inter-frequency, inter-
frequency, and inter-RAT handovers.

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, 512
The spreading factor can be changed every
TTI (10, 20, 40, or 80 ms).
Handover types: Soft & Softer HO (FDD only),
Hard Handover;

Access Stratum
Strata 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 applied
access technique. In UMTS it offers services related to the data transmission via the radio
interface. 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 radio
interface related information. AS signalling is used to inform the UE about how to use the
radio interface in the UL and DL direction.
• UTRAN – CN
The CN requests the access network to make transmission resources available. The
interaction between UTRAN and the CN is hereby independent of the interaction between
the UTRAN and the UE. In other words, the UTRAN – CN access stratum is independent of
the used radio interface technology.
In this course, we focus our interest mainly on the transmission of signalling information
and related parameters via the radio interface. Consequently, the access stratum between
the 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 course
material, this signalling is regarded as part of the non-access stratum.

AS and NAS Signalling
UTRAN
RNC
UE CN Iu edge node
NAS signalling and user data
i.e. MM, PMM & CC, SS, SMS, SM
Access Stratum Signalling
(Uu Stratum)
RRC
Access Stratum Signalling
(Iu Stratum)
RANAP

UMTS QoS Architecture
When 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 be
provided between the two participating terminals. The QoS of an end-to-end bearer service has
to be described. Parameter such as minimum bit rate, guaranteed bit rate, and end-to-end delay
can be used.
An end-to-end bearer service may be made available by several operators. This is the situation
displayed in the figure on the right hand side. The UMTS provider offers the UMTS bearer
service, 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 bearer
service 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 RAB
between the CN Iu edge node and the S-RNC. Between the S-RNC and the UE, the signalling
and control protocol RRC is used to establish Radio Bearer (RB) Services, which is also
required to establish a RAB Service.
The RRC is used peer-to-peer between the UE and the S-RNC. There are two intermediate
devices, 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 adequate
QoS to „higher layer“ bearer services is done with the NBAP. This protocol is also used to
inform the Node B about the transmission and reception of common and dedicated information
on the radio interface Uu. The RNSAP is used between neighbouring RNCs for features such
as inter-RNC soft handovers and S-RNC relocation.

TE TE
CN
GatewayMT UTRAN
CN Iu
edge node
End-to-End Service
TE/MT Local
Bearer Service
External
Bearer Service
UMTS Bearer Service = UMTS QoS
CN
Bearer Service
Radio Access
Bearer Service
Backbone
Bearer Service
Radio
Bearer Service
Iu
Bearer Service
UTRA FDD/TDD
Service
Physical
Bearer Service
(adopted from TS 23.107)

QoS Management Functions in the Control Plane
TE
ext.
network
CN
GatewayMT UTRAN
CN Iu
edge node
UMTS BS
Manager
UMTS BS
Manager
UMTS BS
Manager
RAB
Manager
CN BS
Mana-
ger
Iu BS
Mana-
ger
Ext. BS
Mana-
ger
CN BS
Mana-
ger
Iu BS
Mana-
ger
Radio
BS
Mana-
ger
Radio
BS
Mana-
ger
Local
BS
Mana-
ger
BB NS
Mana-
ger
Iu NS
Mana-
ger
BB NS
Mana-
ger
Iu NS
Mana-
ger
UTRA
ph. BS
Mana-
ger
UTRA
ph. BS
Mana-
ger
Subscr
Control
Adm/
Cap.
Control
Adm/
Cap.
Control
Trans-
lation
Adm/
Cap.
Control
Adm/
Cap.
Control
Trans-
lation
(adopted from
TS 23.107)

In 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 audio
streaming, where music files are downloaded to the receiver. There may be an interruption in
the transmission, which is not relevant for the user of the application, as long as there is still
enough data left in the buffer of the receiving equipment for seamless application provision to
gap the transmission time break.
• Interactive class
is 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 timing
constraints, such as http, ftp, telnet, and smtp. A response to a request is expected within a
specific period of time. This is the QoS offered by the interactive class.
• Background class
is 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 are
listed on the right hand side. When a UMTS bearer is established, modified or released, aspects
such as the UE capabilities, subscription profiles and network specific QoS profiles have to be
taken under consideration.

UMTS Bearer Attributes
Traffic class
Background
class
Interactive
class
Streaming
class
Conversational
class
Maximum bit rate
SDU format
information
SDU error ratio
Residual bit
error ratio
Delivery of
erroneous SDUs
Transfer delay
Guaranteed bit rate
Traffic handling
priority
Allocation/Retention
priority
Delivery order
Maximum SDU size
(adopted from TS 23.107
chap. 6.4.3.3)

UTRAN Specific Signalling and Control Protocols
3G-MSC/VLR
3G-SGSN
UE Node B
RNC
RNC
RNS
RNS
RRC
Iur: RNSAP
Iu-PS: RANAP
Iu-CS: RANAP
Iub: NBAP
TS 25.331TS 25.331
TS 25.433
TS 25.433
TS 25.423TS 25.423
TS 25.413
TS 25.413
TS 25.413TS 25.413

General Protocol Model for UTRAN Interfaces
The general protocol model for UTRAN interfaces can be seen in the figure on the right hand
side. 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 had
been developed, such as the RNSAP. This is one example of an application protocol, as
denoted in the figure. Each signalling and control protocol requires a signalling bearer. The
signalling 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 data
bearers.
Within the transport network layers, there are vertical transport network user and control
planes. 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 and
maintenance. The Transmission resources for the user data streams can be made available
on demand. On some interface, ALCAP is used. It is a transport network control plane
specific signalling protocol to establish, maintain, modify, and release data bearers. It is for
instance in use on the Iu-CS interface, but not on the Iu-PS interface. The signalling bearers
for ALCAP are always set up by operations and maintenance.

Physical Layer
(copied from TS 25.401 chap. 11.1.1)
Control Plane User PlaneRadio
Network
Layer
Transport
Network
Layer
Application
Protocol
Signalling
Bearer(s)
Signalling
Bearer(s)
Data
Bearer(s)
ALCAP
Data
Streams
Transport Network
Control Plane User Plane
Transport Network
User Plane
Transport Network

The figure on the right hand side shows the Uu access stratum protocols as implemented in
the 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 radio
resources. The RRC protocol‘s peer entities are the RNC and the Node B. The receiving
entity 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.

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
RLC
RLC
RLC
RLC
RLC
RLC
RLC
RLC
BMC
PDCP
PDCP
PDCP
PhyCHs
LogCHs
RBs
control
control
control
control
control

References
For 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

GSM & UMTS Evolution
1990/91 1994 97 98 1999/2000 01 year
Phase 1
Tele & Bearer
Services
FR speech
SMS
Data ≤ 9.6 kbps
Phase 2
Supplementary
Services
HR speech
‘96 ‘97 ‘98 ‘99
‘99
Phase 2+
• HSCSD, GPRS & EDGE
• PS Domain
• New Services
• IN-applications
• EFR & AMR
• ….
Annual Release
R4 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
?
2G
2.5G
3G
3.5G
4

Radio Protocol Architecture
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