3G

1. 3G Systems

3G Systems are intended to provide a global mobility with wide range of services

including telephony, paging, messaging, Internet and broadband data. International

Telecommunication Union (ITU) started the process of defining the standard for third

generation systems, referred to as International Mobile Telecommunications 2000

(IMT-2000). In Europe European Telecommunications Standards Institute (ETSI) was

responsible of UMTS standardisation process. In 1998 Third Generation Partnership

Project (3GPP) was formed to continue the technical specification work. 3GPP has

five main UMTS standardisation areas: Radio Access Network, Core Network,

Terminals, Services and System Aspects and GERAN.

3GPP Radio Access group is responsible of:

• Radio Layer 1, 2 and 3 RR specification

• Iub, Iur and Iu Interfaces

• UTRAN Operation and Maintenance requirements

• BTS radio performance specification

• Conformance test specification for testing of radio aspects of base stations

• Specifications for radio performance aspects from the system point of view

3GPP Core Network group is responsible of:

• Mobility management, call connection control signalling between the user

equipment and the core network.

• Core network signalling between the core network nodes.

• Definition of interworking functions between the core network and external

networks.

• Packet related issues.

• Core network aspects of the lu interface and Operation and Maintenance

requirements

3GPP Terminal group is responsible of:

• Service capability protocols

• Messaging

• Services end-to-end interworking

• USIM to Mobile Terminal interface

• Model/framework for terminal interfaces and services (application) execution

• Conformance test specifications of terminals, including radio aspects

3GPP Services and System Aspects group is responsible of:

• Definition of services and feature requirements.

• Development of service capabilities and service architecture for cellular, fixed and

cordless applications.

• Charging and Accounting

• Network Management and Security Aspects

• Definition, evolution, and maintenance of overall architecture.

Third Generation Partnership Project 2 (3GPP) was formed for technical development

of cdma2000 technology which is a member of IMT-2000 family.

In February 1992 World Radio Conference allocated frequencies for UMTS use.

Frequencies 1885 - 2025 and 2110 - 2200 MHz were identified for IMT-2000 use.

See the UMTS Frequency page for more details. All 3G standards are still under

constant development. In 1999 ETSI Standardisation finished for UMTS Phase 1

(Release '99, version 3) and next release is due December 2001. UMTS History page

has a list of all major 3G and UMTS milestones. Most of the European countries and

some countries round the world have already issued UMTS licenses either by beauty

contest or auctions.

2. UMTS Services

UMTS offers teleservices (like speech or SMS) and bearer services, which provide

the capability for information transfer between access points. It is possible to

negotiate and renegotiate the characteristics of a bearer service at session or

connection establishment and during ongoing session or connection. Both connection

oriented and connectionless services are offered for Point-to-Point and Point-to-

Multipoint communication.

Bearer services have different QoS parameters for maximum transfer delay, delay

variation and bit error rate. Offered data rate targets are:

• 144 kbits/s satellite and rural outdoor

• 384 kbits/s urban outdoor

• 2048 kbits/s indoor and low range outdoor

UMTS network services have different QoS classes for four types of traffic:

• Conversational class (voice, video telephony, video gaming)

• Streaming class (multimedia, video on demand, webcast)

• Interactive class (web browsing, network gaming, database access)

• Background class (email, SMS, downloading)

UMTS will also have a Virtual Home Environment (VHE). It is a concept for

personal service environment portability across network boundaries and between

terminals. Personal service environment means that users are consistently presented

with the same personalised features, User Interface customisation and services in

whatever network or terminal, wherever the user may be located. UMTS also has

improved network security and location based services.

3. UMTS Architecture

A UMTS network consist of three interacting domains; Core Network (CN), UMTS

Terrestrial Radio Access Network (UTRAN) and User Equipment (UE). The main

function of the core network is to provide switching, routing and transit for user

traffic. Core network also contains the databases and network management functions.

The basic Core Network architecture for UMTS is based on GSM network with

GPRS. All equipment has to be modified for UMTS operation and services. The

UTRAN provides the air interface access method for User Equipment. Base Station is

referred as Node-B and control equipment for Node-B's is called Radio Network

Controller (RNC). UMTS system page has an example, how UMTS network could be

build.

It is necessary for a network to know the approximate location in order to be able to

page user equipment. Here is the list of system areas from largest to smallest.

• UMTS systems (including satellite)

• Public Land Mobile Network (PLMN)

• MSC/VLR or SGSN

• Location Area

• Routing Area (PS domain)

• UTRAN Registration Area (PS domain)

• Cell

• Sub cell

4. Core Network

The Core Network is divided in circuit switched and packet switched domains. Some

of the circuit switched elements are Mobile services Switching Centre (MSC), Visitor

location register (VLR) and Gateway MSC. Packet switched elements are Serving

GPRS Support Node (SGSN) and Gateway GPRS Support Node (GGSN). Some

network elements, like EIR, HLR, VLR and AUC are shared by both domains.

The Asynchronous Transfer Mode (ATM) is defined for UMTS core transmission.

ATM Adaptation Layer type 2 (AAL2) handles circuit switched connection and

packet connection protocol AAL5 is designed for data delivery.

The architecture of the Core Network may change when new services and features are

introduced. Number Portability DataBase (NPDB) will be used to enable user to

change the network while keeping their old phone number. Gateway Location

Register (GLR) may be used to optimise the subscriber handling between network

boundaries. MSC, VLR and SGSN can merge to become a UMTS MSC.

5. Radio Access

Wide band CDMA technology was selected to for UTRAN air interface. UMTS

WCDMA is a Direct Sequence CDMA system where user data is multiplied with

quasi-random bits derived from WCDMA Spreading codes. In UMTS, in addition to

channelisation, Codes are used for synchronisation and scrambling. WCDMA has two

basic modes of operation: Frequency Division Duplex (FDD) and Time Division

Duplex (TDD). UTRAN interfaces are shown on UMTS Network page.

The functions of Node-B are:

• Air interface Transmission / Reception

• Modulation / Demodulation

• CDMA Physical Channel coding

• Micro Diversity

• Error Handing

• Closed loop power control

The functions of RNC are:

• Radio Resource Control

• Admission Control

• Channel Allocation

• Power Control Settings

• Handover Control

• Macro Diversity

• Ciphering

• Segmentation / Reassembly

• Broadcast Signalling

• Open Loop Power Control

6. User Equipment

The UMTS standard does not restrict the functionality of the User Equipment in any

way. Terminals work as an air interface counter part for Node-B and have many

different types of identities. Most of these UMTS identity types are taken directly

from GSM specifications.

• International Mobile Subscriber Identity (IMSI)

• Temporary Mobile Subscriber Identity (TMSI)

• Packet Temporary Mobile Subscriber Identity (P-TMSI)

• Temporary Logical Link Identity (TLLI)

• Mobile station ISDN (MSISDN)

• International Mobile Station Equipment Identity (IMEI)

• International Mobile Station Equipment Identity and Software Number (IMEISV)

UMTS mobile station can operate in one of three modes of operation:

• PS/CS mode of operation: The MS is attached to both the PS domain and CS

domain, and the MS is capable of simultaneously operating PS services and CS

services.

• PS mode of operation: The MS is attached to the PS domain only and may only

operate services of the PS domain. However, this does not prevent CS-like services to

be offered over the PS domain (like VoIP).

• CS mode of operation: The MS is attached to the CS domain only and may only

operate services of the CS domain.

UMTS IC card has same physical characteristics as GSM SIM card. It has several

functions:

• Support of one User Service Identity Module (USIM) application (optionally more

that one)

• Support of one or more user profile on the USIM

• Update USIM specific information over the air

• Security functions

• User authentication

• Optional inclusion of payment methods

• Optional secure downloading of new applications

UMTS Network

Picture below shows how an UMTS 3G network could be build.

UMTS network layout example

3G Frequencies

According to "WARC-92 frequencies for IMT-2000" resolution: "The bands 1885-

2025 MHz and 2110-2200 MHz are intended for use, on a worldwide basis, by

administrations wishing to implement International Mobile Telecommunications-2000

(IMT-2000). Such use does not preclude the use of these bands by other services to

which they are allocated."

Here is the summary of UMTS frequencies:

1920-1980 and 2110-2170 MHz Frequency Division Duplex (FDD, W-CDMA)

Paired uplink and downlink, channel spacing is 5 MHz and raster is 200 kHz. An

Operator needs 3 - 4 channels (2x15 MHz or 2x20 MHz) to be able to build a high-

speed, high-capacity network.

1900-1920 and 2010-2025 MHz Time Division Duplex (TDD, TD/CDMA) Unpaired,

channel spacing is 5 MHz and raster is 200 kHz. Tx and Rx are not separated in

frequency.

1980-2010 and 2170-2200 MHz Satellite uplink and downlink.

Carrier frequencies are designated by a UTRA Absolute Radio Frequency Channel

Number (UARFCN). The general formula relating frequency to UARFN is:

UARFCN = 5 * (frequency in MHz)

WARC-92 IMT-2000 Frequencies

WRC-2000 in Istanbul

• Identified the bands 1710 - 1885 and 2500 - 2690 MHz for IMT-2000

• Identified those parts of the band 806 - 960 MHz which are allocated to the mobile

service on a primary basis

• Admitted that High Altitude Platform Stations (HAPS) may use the WARC-92

frequency bands for terrestrial IMT-2000 on restrictive conditions

• Decided that the frequency bands 1525 - 1544, 1545 - 1559, 1610 - 1626.5, 1626.5

- 1645.5, 1646.5 - 1660.5 and 2483.5 - 2500 MHz may be used for the satellite

component of IMT-2000, as well as the bands 2500 - 2520 MHz and 2670- 2690

MHz, depending on market developments

• Decided that "the bands, or portions of the bands, 1710 - 1885 MHz and 2500 -

2690 MHz, are identified for use by administrations wishing to implement

International Mobile Telecommunications-2000 (IMT-2000). This identification does

not preclude the use of these bands by any application of the services to which they

are allocated and does not establish priority in the Radio Regulations".

WRC-2000 IMT-2000 Frequencies

From the TS 25.101 Specification:

UTRA FDD frequency bands

TX-RX frequency separation

UARFCN definition

UARFCN definition (Band II additional channels)

UTRA Absolute Radio Frequency Channel Number

Channel Multiplexing Structure

This is a short overview how data stream is modified during processing in layer 2 and

1 in downlink direction. Uplink coding is done in a similar way.

Ciphering happens in RCL or MAC-d part of the layer 2. f8 algorithm gets five inputs

to generate a keystream block that is ciphered by binary addition to a data stream.

Channel coding separates different down link connection to users within a cell. In the

uplink direction Channel coding is used for separation of physical data and control

channels. Half-rate and 1/3-rate convolutional coding is used for low data rates, turbo

coding is used for higher bit rates. Channel coding includes the spreading. Rate

matching is dynamic frame-by-frame operation and done either by puncturing or by

repetition of the data stream. Interleaving is done in two stages. It is first done by

inter-frame and then by intra-frame.

Transport channel multiplexing structure for downlink

WCDMA Link Budget

Link budget planning is part of the network planning process, which helps to

dimension the required coverage, capacity and quality of service requirement in the

network. UMTS WCDMA macro cell coverage is uplink limited, because mobiles

power level is limited to (voice terminal 125mW). Downlink direction limits the

available capacity of the cell, as BTS transmission power (typically 20-40W) has to

be divided to all users. In a network environment both coverage and capacity are

interlinked by interference. So by improving one side of the equation would decrease

the other side. System is loosely balanced by design. The object of the link budget

design is to calculate maximum cell size under given criteria:

• Type of service (data type and speed)

• Type of environment (terrain, building penetration)

• Behavior and type of mobile (speed, max power level)

• System configuration (BTS antennas, BTS power, cable losses, handover gain)

• Required coverage probability

• Financial and economical factors (use of more expensive and better quality

equipment or not the cheapest installation method)

and to match all of those to the required system coverage, capacity and quality needs

with each area and service.

In an urban area, capacity will be the limiting factor, so inner city cells will be

dimensioned by required Erlangs/km² for voice and data. Even using 25dB as

inbuilding penetration loss into the building core area, link budget would typically

allow about 300m cell range, which is a way too much for a capacity purposes. In a

rural area uplink power budget will determine the maximum cell range, when

typically cells are less congested. A typical cell range in rural areas will be several

kilometers depending on a terrain.

Below is an example of how WCDMA voice call link budget can be done. Some of

the values can be debated, including the propagation model, but it gives an idea of the

calculation methods.

UMTS link budget

UMTS Security

The security functions of UMTS are based on what was implemented in GSM. Some

of the security functions have been added and some existing have been improved.

Encryption algorithm is stronger and included in base station (NODE-B) to radio

network controller (RNC) interface , the application of authentication algorithms is

stricter and subscriber confidentially is tighter.

The main security elements that are from GSM:

• Authentication of subscribers

• Subscriber identity confidentially

• Subscriber Identity Module (SIM) to be removable from terminal hardware

• Radio interface encryption

Additional UMTS security features:

• Security against using false base stations with mutual authentication

• Encryption extended from air interface only to include Node-B to RNC connection

• Security data in the network will be protected in data storages and while

transmitting ciphering keys and authentication data in the system.

• Mechanism for upgrading security features.

Core network traffic between RNCs, MSCs and other networks is not ciphered and

operators can to implement protections for their core network transmission links, but

that is unlike to happen. MSCs will have by design a lawful interception capabilities

and access to Call Data Records (SDR), so all switches will have to have security

measures against unlawful access.

UMTS specification has five security feature groups:

• Network access security: the set of security features that provide users with secure

access to 3G services, and which in particular protect against attacks on the (radio)

access link;

• Network domain security: the set of security features that enable nodes in the

provider domain to securely exchange signalling data, and protect against attacks on

the wireline network;

• User domain security: the set of security features that secure access to mobile

stations

• Application domain security: the set of security features that enable applications

in the user and in the provider domain to securely exchange messages.

• Visibility and configurability of security: the set of features that enables the user

to inform himself whether a security feature is in operation or not and whether the use

and provision of services should depend on the security feature.

UMTS specification has the following user identity confidentiality security features:

• User identity confidentiality: the property that the permanent user identity (IMSI)

of a user to whom a services is delivered cannot be eavesdropped on the radio access

link;

• User location confidentiality: the property that the presence or the arrival of a user

in a certain area cannot be determined by eavesdropping on the radio access link;

• User untraceability: the property that an intruder cannot deduce whether different

services are delivered to the same user by eavesdropping on the radio access link.

Air interface ciphering/deciphering in performed in RNC in the network side and in

mobile terminals. Ciphering in function of air interface protocol Radio Link Control

(RLC) layer or Medium Access control (MAC) layer.

Main UMTS Codes

Here us a summary of the main UMTS FDD codes:

Synchronisation

Codes

Channelisation

Codes

Scrambling

Codes, UL

Scrambling

Codes, DL

Type

Gold Codes

Primary Synchronization

Codes (PSC) and

Secondary

Synchronization Codes

(SSC)

Orthogonal

Variable

Spreading Factor

(OVSF) codes

sometimes called

Walsh Codes

Complex-

Valued Gold

Code Segments

(long) or

Complex-

Valued S(2)

Codes (short)

Pseudo Noise (PN)

codes

Complex-

Valued Gold

Code

Segments

Pseudo Noise

(PN) codes

Length 256 chips 4-512 chips 38400 chips /

256 chips 38400 chips

Duration 66.67 µs 1.04 µs -

133.34 µs 10 ms / 66.67 µs 10 ms

Number

of codes

1 primary code / 16

secondary codes

= spreading factor

4 ... 256 UL,

4 ... 512 DL

16,777,216

512 primary /

15 secondary

for each

primary code

Spreading No, does not change

bandwidth

Yes, increases

bandwidth

No, does not

change

bandwidth

No, does not

change

bandwidth

Usage

To enable terminals

to locate and

synchronise to the

cells' main control

channels

UL: to separate

physical data and

control data from

same terminal

DL: to separate

connection to

different terminals

in a same cell

Separation of

terminal

Separation of

sectors

Further reading: 3GPP TS 25.201, 25.213, 25.223

Synchronisation

Different UTRAN synchronisation required in a 3G network:

• Network synchronisation

• Node synchronisation

• Transport channel synchronisation

• Radio interface cynchronisation

• Time alignment handling

Synchronisation Issues Model

Network Synchronisation relates to the distribution of synchronisation references to

the UTRAN Nodes and the stability of the clocks in the UTRAN (and performance

requirements on UTRAN internal interfaces). The distribution of an accurate

frequency reference to the network elements in the UTRAN is related to several

aspects. One main issue is the possibility to provide a synchronisation reference with

a frequency accuracy better than 0.05 ppm at the Node B in order to properly generate

signals on the radio interface.

Node Synchronisation relates to the estimation and compensation of timing

differences among UTRAN nodes. FDD and TDD modes have different requirements

on the accuracy of the timing difference estimation and on the necessity to

compensate for these differences. Positioning / Localisation functions may also set

requirements on Node Synchronisation.

The Transport Channel Synchronisation mechanism defines synchronisation of the

frame transport between RNC and Node B, considering radio interface timing.

The Radio Interface Synchronisation relates to the timing of the radio frame

transmission (either in downlink [FDD] or in both directions [TDD]). FDD and TDD

have different mechanisms to determine the exact timing of the radio frame

transmission and also different requirements on the accuracy of this timing. In FDD

Radio Interface Synchronisation is necessary to assure that the UE receives radio

frames synchronously from different cells, in order to minimise UE buffers.

The Time Alignment Handling procedure over Iu relates to the control of DL

transmission timing in the CN nodes in order to minimise the buffer delay in SRNC.

This procedure is controlled by SRNC.

Further reading: 3GPP TS 25.402

Co-location, Isolations

Spurious emissions are emissions, which are caused by unwanted transmitter effects

such as harmonics emission, parasitic emission, intermodulation products and

frequency conversion products, but exclude out of band emissions. This is measured

at the base station RF output port.

Spectrum Emission Mask, 3GPP TS 25.104 Fig. 6.2

Spurious emissions limits for protection of the BS receiver

The table above corresponds to -80 dBm / 3.84MHz spurious emission requirements

from UMTS DL to UMTS UL.

EXAMPLE

Spurious emission DL to

UL - 80 dBm See above

Max sensitivity

degradation

- 121

dBm

BS reference

sensitivity

Min required isolation 41 dB

UMTS FDD isolation requirement due to spurious emissions Note: Check with your vendor, they will quote a lower figure

The receiver blocking characteristics is a measure of the receiver ability to receive a

wanted signal at its assigned channel frequency in the presence of an unwanted

interferer on frequencies other than those of the adjacent channels.

EXAMPLE

Max Node B power 43 dBm = 20W

Blocking level - 40 dBm 3GPP 25104 7.5.1

Min required isolation 83 dB

UMTS FDD - FDD isolation requirement due to receiver blocking Note: Check with your vendor, they will quote a lower figure

The transmit intermodulation performance is a measure of the capability of the

transmitter to inhibit the generation of signals in its non linear elements caused by

presence of the wanted signal and an interfering signal reaching the transmitter via the

antenna. The transmit intermodulation level shall not exceed the out of band emission

or the spurious emission requirements.

Summary: Co-location and isolation related issues

• Co-location issues; base station receivers; spurious emission and blocking

• Co-existence issues; mobile phone receivers; spurious emission and blocking

• Intermodulation issues

• All wireless systems need to be considered

• Vendor equipment specification far better that 3GPP specifications

Solution considerations

• Equipment specifications

• Horisontal antenna separation

• Vertical antenna separation

• Additional filtering

• Antenna beamwidth

• Antenna bearing

• Frequency coordination with other carriers

• Smart designs for common antenna systems

Further reading: 3GPP TS 25.104, GSM 05.05, ITU-R SM.329-9

3G and LAN Date Speeds

Here are the theoretical maximum data speeds of 2G, 2.5G, 3G and beyond, and

compared to LAN data speeds.

Data Speed of Mobile Systems (top) and LANs (bottom)

UMTS Time Slots

UMTS has several different time slot configuration depending on the used channel.

Here is an example of DPCH (Dedicated Physical Channel) downlink and uplink time

slot allocation.

TCP stands for Transmit Power Control, Feedback Information (FBI) is used for

closed loop transmission diversity. Transport Format Combination Indicator (TFCI)

contains the information relating to data rates. Pilot bits are always the same and are

used for channel synchronisation.

DPCH Time Slot Structure

UTRA Channels

UTRA FDD radio interface has logical channels, which are mapped to transport

channels, which are again mapped to physical channels. Logical to Transport channel

conversion happens in Medium Access Control (MAC) layer, which is a lower

sublayer in Data Link Layer (Layer 2).

Logical Channels: Broadcast Control Channel (BCCH), Downlink (DL)

Paging Control Channel (PCCH), DL

Dedicated Control Channel (DCCH), UL/DL

Common Control Channel (CCCH), UL/DL

Dedicated Traffic Channel (DTCH), UL/DL

Common Traffic Channel (CTCH), Unidirectional (one to many)

Transport Channels: Dedicated Transport Channel (DCH), UL/DL, mapped to DCCH and DTCH

Broadcast Channel (BCH), DL, mapped to BCCH

Forward Access Channel (FACH), DL, mapped to BCCH, CCCH, CTCH, DCCH and

DTCH

Paging Channel (PCH), DL, mapped to PCCH

Random Access Channel (RACH), UL, mapped to CCCH, DCCH and DTCH

Uplink Common Packet Channel (CPCH), UL, mapped to DCCH and DTCH

Downlink Shared Channel (DSCH), DL, mapped to DCCH and DTCH

Physical Channels: Primary Common Control Physical Channel (PCCPCH), mapped to BCH

Secondary Common Control Physical Channel (SCCPCH), mapped to FACH, PCH

Physical Random Access Channel (PRACH), mapped to RACH

Dedicated Physical Data Channel (DPDCH), mapped to DCH

Dedicated Physical Control Channel (DPCCH), mapped to DCH

Physical Downlink Shared Channel (PDSCH), mapped to DSCH

Physical Common Packet Channel (PCPCH), mapped to CPCH

Synchronisation Channel (SCH)

Common Pilot Channel (CPICH)

Acquisition Indicator Channel (AICH)

Paging Indication Channel (PICH)

CPCH Status Indication Channel (CSICH)

Collision Detection/Channel Assignment Indication Channel (CD/CA-ICH)

UTRA Channels

WCDMA Spreading

TDD WCDMA uses spreading factors 4 - 512 to spread the base band data over

~5MHz band. Spreading factor in dBs indicates the process gain. Spreading factor

128 = 21 dB process gain). Interference margin is calculated from that:

Interference Margin = Process Gain - (Required SNR + System Losses)

• Required Signal to Noise Ration is typically about 5 dB

• System losses are defined as losses in receiver path. System losses are typically 4 -

6 dBs

Overview of Spreading Process

Quality of Service

Network Services are considered end-to-end, this means from a Terminal Equipment

(TE) to another TE. An End-to-End Service may have a certain Quality of Service

(QoS) which is provided for the user of a network service. It is the user that decides

whether he is satisfied with the provided QoS or not.

To realise a certain network QoS a Bearer Service with clearly defined characteristics

and functionality is to be set up from the source to the destination of a service.

A bearer service includes all aspects to enable the provision of a contracted QoS.

These aspects are among others the control signalling, user plane transport and QoS

management functionality. A UMTS bearer service layered architecture is depicted

below, each bearer service on a specific layer offers it's individual services using

services provided by the layers below.

QoS Architecture

There are four different QoS classes:

• conversational class

• streaming class

• interactive class

• background class

Traffic class Conversational

class

Real Time

Streaming

class

Real Time

Interactive

class

Best Effort

Background

class

Best Effort

Fundamental

characteristics

- Preserve time

relation (variation)

between

information

entities of the

stream

- Preserve time

relation

(variation)

between

information

entities of the

stream

- Request

response pattern

-Preserve

payload content

-Destination is

not expecting the

data within a

certain time

-Preserve

- Conversational

pattern (stringent

and low delay )

payload content

Example of the

application

voice streaming

video

web browsing telemetry,

emails

UMTS QoS classes

List of UMTS Bearer Service Attributes:

• Traffic class ('conversational', 'streaming', 'interactive', 'background')

• Maximum bit rate (kbps)

• Guaranteed bit rate (kbps)

• Delivery order (y/n)

• Maximum SDU size (octets)

• SDU format information (bits)

• SDU error ratio

• Residual bit error ratio

• Delivery of erroneous SDUs (y/n/-)

• Transfer delay (ms)

• Traffic handling priority

• Allocation/Retention Priority

• Source statistics descriptor ('speech'/'unknown')

SDU = Service Data Unit

Further reading: 3GPP 23.107

Channel Coding

Channel coding and multiplexing example for DTCH and DCCH:

Channel coding example for the UL 64 kbps channel

Further reading: 3GPP TS 25.104, 25.944

Multimedia Messaging Service (MMS); Media formats and codecs

Multiple media elements shall be combined into a composite single MM using MIME

multipart format. The media type of a single MM element shall be identified by its

appropriate MIME type whereas the media format shall be indicated by its appropriate

MIME subtype. In order to guarantee a minimum support and compatibility between

multimedia messaging capable terminals, MMS User Agent supporting specific media

types shall comply with the following selection of media formats:

Text

Plain text. Any character encoding (charset) that contains a subset of the logical

characters in Unicode shall be used (e.g. US-ASCII, ISO-8859-1, UTF-8, Shift_JIS,

etc.). Unrecognized subtypes of "text" shall be treated as subtype "plain" as long as

the MIME implementation knows how to handle the charset. Any other unrecognized

subtype and unrecognized charset shall be treated as "application/octet - stream".

Speech

The AMR codec shall be supported for narrow-band speech.

The AMR wideband speech codec shall be supported when wideband speech working

at 16 kHz sampling frequency is supported.

Source codec bit-rates for the AMR codec

Audio

MPEG-4 AAC Low Complexity object type should be supported. The maximum

sampling rate to be supported by the decoder is 48 kHz. The channel configurations to

be supported are mono (1/0) and stereo (2/0). In addition, the MPEG-4 AAC Long

Term Prediction object type may be supported.

Synthetic audio

The Scalable Polyphony MIDI (SP-MIDI) content format defined in Scalable

Polyphony MIDI Specification and the device requirements defined in Scalable

Polyphony MIDI Device 5-to-24 Note Profile for 3GPP should be supported. SP-

MIDI content is delivered in the structure specified in Standard MIDI Files 1.0, either

in format 0 or format 1.

Still Image

ISO/IEC JPEG together with JFIF shall be supported. The support for ISO/IEC JPEG

only apply to the following two modes:

• mandatory: baseline DCT, non-differential, Huffman coding

• optional: progressive DCT, non-differential, Huffman coding

Bitmap graphics

The following bitmap graphics formats should be supported:

• GIF87a

• GIF89a

• PNG

Video

For terminals supporting media type video, ITU-T Recommendation H.263 profile 0

level 10 shall be supported. This is the mandatory video codec for the MMS. In

addition, MMS should support:

• H.263 Profile 3 Level 10

• MPEG-4 Visual Simple Profile Level 0

These two video codecs are optional to implement.

NOTE: ITU-T Recommendation H.263 baseline has been mandated to ensure that

video-enabled MMS support a minimum baseline video capability and

interoperability can be guaranteed (an H.263 baseline bitstream can be decoded by

both H.263 and MPEG-4 decoders). It also provides a simple upgrade path for

mandating more advanced codecs in the future (from both the ITU-T and ISO

MPEG).

ITU press release regarding H.264 video compression standard (23/12/02)

Etsi and Digital Video Broadcasting Project are developing DVB-X standard for

UMTS. Read the EETimes article. (11/10/03)

Vector graphics

For terminals supporting media type "2D vector graphics" the "Tiny" profile of the

Scalable Vector Graphics (SVG-Tiny) format shall be supported, and the "Basic"

profile of the Scalable Vector Graphics (SVG-Basic) format may be supported.

World Wide Web Consortium Issues Scalable Vector Graphics (SVG) 1.1 and Mobile

SVG as W3C Recommendations (14/01/03)

File format for dynamic media

The file format used in the present document for timed multimedia (such as video,

associated audio and timed text) is structurally based on the MP4 file format.

However, since non-ISO codecs are used here, it is called the 3GPP file format and

has its own file extension and MIME type to distinguish these files from MPEG-4

files. When the present document refers to the MP4 file format, it is referring to its

structure (ISO file format), not to its conformance definition.

To ensure interoperability for the transport of video and associated speech/audio and

timed text in an MM, the MP4 file format shall be supported. The usage of the MP4

file format shall follow the technical specifications and the implementation guidelines

specified in TS 26.234.

Media synchronization and presentation format

The mandatory format for media synchronization and scene description of multimedia

messaging is SMIL.

• The 3GPP MMS uses a subset of SMIL 2.0 as format of the scene description.

MMS clients and servers with support for scene descriptions shall support the 3GPP

PSS5 SMIL Language Profile. This profile is a subset of the SMIL 2.0 Language

Profile but a superset of the SMIL 2.0 Basic Language Profile. TS 26.234 also

includes an informative annex B that provides guidelines for SMIL content authors.

Additionally, 3GPP MMS should provide the following format:

• XHTML Mobile Profile

• The 3GPP MMS uses a subset of XHTML 1.1 as a format for scene description.

MMS clients and servers with support for scene descriptions shall support XHTML

Mobile Profile, defined by the WAP Forum. XHTML Mobile Profile is a subset of

XHTML 1.1 but a superset of XHTML Basic.

Further reading: 3GPP 26071, 3GPP 26140

Compressed Mode

During inter-frequency handover the UE’s must be given time to make the necessary

measurements on the different WCDMA carrier frequency. 1 to 7 slots per frame can

be allocated for the UE to perform this intra frequency (hard handover). These slots

can either be in the middle of the single frame or spread over two frames.

This compressed mode operation can be achieved in three different methods:

• Decreasing the spreading factor by 2:1. This will increase the data rate so bits will

get sent twice as fast.

• Puncturing bits. This will remove various bits from the original data and hence

reduce the amount of information that needs to be transmitted.

• The higher layer scheduling could also be changed to use less timeslots for user

traffic.

From the 3GPP TS 25.212:

In compressed frames, Transmission Gap Length slots from Nfirst to Nlast are not

used for transmission of data. As illustrated below, the instantaneous transmit power

is increased in the compressed frame in order to keep the quality (BER, FER, etc.)

unaffected by the reduced processing gain. The amount of power increase depends on

the transmission time reduction method. What frames are compressed, are decided by

the network. When in compressed mode, compressed frames can occur periodically,

or requested on demand. The rate and type of compressed frames is variable and

depends on the environment and the measurement requirements.

The frame structure for uplink compressed frames is illustrated below.

There are two different types of frame structures defined for downlink compressed

frames. Type A maximises the transmission gap length and type B is optimised for

power control. The frame structure type A or B is set by higher layers independent

from the downlink slot format type A or B.

• With frame structure of type A, the pilot field of the last slot in the transmission gap

is transmitted. Transmission is turned off during the rest of the transmission gap

(below).

• With frame structure of type B, the TPC field of the first slot in the transmission

gap and the pilot field of the last slot in the transmission gap is transmitted.

Transmission is turned off during the rest of the transmission gap (below).


HSDPA in W-CDMA

High Speed Downlink Packet Access (HSDPA) is a packet-based data service in W-

CDMA downlink with data transmission up to 8-10 Mbps (and 20 Mbps for MIMO

systems) over a 5MHz bandwidth in WCDMA downlink. HSDPA implementations

includes Adaptive Modulation and Coding (AMC), Multiple-Input Multiple-Output

(MIMO), Hybrid Automatic Request (HARQ), fast cell search, and advanced receiver

design.

In 3rd generation partnership project (3GPP) standards, Release 4 specifications

provide efficient IP support enabling provision of services through an all-IP core

network and Release 5 specifications focus on HSDPA to provide data rates up to

approximately 10 Mbps to support packet-based multimedia services. MIMO systems

are the work item in Release 6 specifications, which will support even higher data

transmission rates up to 20 Mbps. HSDPA is evolved from and backward compatible

with Release 99 WCDMA systems.

Currently (2002) 3GPP is undertaking a feasibility study on high-speed downlink

packet access.

HSPDA and CDMA2000 1xEV-DV Comparison

3GPP TS 25.855 High Speed Downlink Packet Access (HSDPA); Overall UTRAN

description

3GPP TS 25.856 High Speed Downlink Packet Access (HSDPA); Layer 2 and 3

aspects

3GPP TS 25.876 Multiple-Input Multiple-Output Antenna Processing for HSDPA

3GPP TS 25.877 High Speed Downlink Packet Access (HSDPA) - Iub/Iur Protocol

Aspects

3GPP TS 25.890 High Speed Downlink Packet Access (HSDPA); User Equipment

(UE) radio transmission and reception (FDD)

Lucent announced the world's first turbo decoder chip for HSDPA UMTS terminals (11/02/03)

UMTS Handover

There are following categories of handover (also referred to as handoff):

• Hard Handover

Hard handover means that all the old radio links in the UE are removed before the

new radio links are established. Hard handover can be seamless or non-seamless.

Seamless hard handover means that the handover is not perceptible to the user. In

practice a handover that requires a change of the carrier frequency (inter-frequency

handover) is always performed as hard handover.

• Soft Handover

Soft handover means that the radio links are added and removed in a way that the UE

always keeps at least one radio link to the UTRAN. Soft handover is performed by

means of macro diversity, which refers to the condition that several radio links are

active at the same time. Normally soft handover can be used when cells operated on

the same frequency are changed.

• Softer handover

Softer handover is a special case of soft handover where the radio links that are added

and removed belong to the same Node B (i.e. the site of co-located base stations from

which several sector-cells are served. In softer handover, macro diversity with

maximum ratio combining can be performed in the Node B, whereas generally in soft

handover on the downlink, macro diversity with selection combining is applied.

Generally we can distinguish between intra-cell handover and inter-cell handover. For

UMTS the following types of handover are specified:

• Handover 3G -3G (i.e. between UMTS and other 3G systems)

• FDD soft/softer handover

• FDD inter-frequency hard handover

• FDD/TDD handover (change of cell)

• TDD/FDD handover (change of cell)

• TDD/TDD handover

• Handover 3G - 2G (e.g. handover to GSM)

• Handover 2G - 3G (e.g. handover from GSM)

The most obvious cause for performing a handover is that due to its movement a user

can be served in another cell more efficiently (like less power emission, less

interference). It may however also be performed for other reasons such as system load

control.

• Active Set is defined as the set of Node-Bs the UE is simultaneously connected to

(i.e., the UTRA cells currently assigning a downlink DPCH to the UE constitute the

active set).

• Cells, which are not included in the active set, but are included in the

CELL_INFO_LIST belong to the Monitored Set.

• Cells detected by the UE, which are neither in the CELL_INFO_LIST nor in the

active set belong to the Detected Set. Reporting of measurements of the detected set

is only applicable to intra-frequency measurements made by UEs in CELL_DCH

state.

The different types of air interface measurements are:

• Intra-frequency measurements: measurements on downlink physical channels at

the same frequency as the active set. A measurement object corresponds to one cell.

• Inter-frequency measurements: measurements on downlink physical channels at

frequencies that differ from the frequency of the active set. A measurement object

corresponds to one cell.

• Inter-RAT measurements: measurements on downlink physical channels

belonging to another radio access technology than UTRAN, e.g. GSM. A

measurement object corresponds to one cell.

• Traffic volume measurements: measurements on uplink traffic volume. A

measurement object corresponds to one cell.

• Quality measurements: Measurements of downlink quality parameters, e.g.

downlink transport block error rate. A measurement object corresponds to one

transport channel in case of BLER. A measurement object corresponds to one timeslot

in case of SIR (TDD only).

• UE-internal measurements: Measurements of UE transmission power and UE

received signal level.

• UE positioning measurements: Measurements of UE position.

The UE supports a number of measurements running in parallel. The UE also supports

that each measurement is controlled and reported independently of every other

measurement.

UMTS Location Based Services

UMTS networks will support location service features, to allow new and innovative

location based services to be developed. It will be possible to identify and report in a

standard format (e.g. geographical co-ordinates) the current location of the user's

terminal and to make the information available to the user, ME, network operator,

service provider, value added service providers and for PLMN internal operations.

The location is provided to identify the likely location of specific MEs. This is meant

to be used for charging, location-based services, lawful interception, emergency calls,

etc., as well as the positioning services.

Location Information consists of:

• Geographic Location

• Velocity (the combination of speed and heading )

• Quality of Service information (horizontal & vertical accuracy and response time)

3GPP specification also describes location based service reliability, priority, security,

privacy and other related aspects.

Location-

independent Most existing cellular services, stock prices, sports reports

PLMN or

country Services that are restricted to one country or one PLMN

Regional

(up to 200km) Weather reports, localized weather warnings, traffic information (pre-trip)

District

(up to 20km) Local news, traffic reports

Up to 1 km Vehicle asset management, targeted congestion avoidance advice

500m to 1km Rural and suburban emergency services, manpower planning, information

services (where are?)

100m (67%)

300m (95%) U.S. FCC mandate (99-245) for wireless emergency calls using network based

positioning methods

75m-125m Urban SOS, localized advertising, home zone pricing, network maintenance,

network demand monitoring, asset tracking, information services (where is the

nearest?)

50m (67%)

150m (95%) U.S. FCC mandate (99-245) for wireless emergency calls using handset based

positioning methods

10m-50m Asset Location, route guidance, navigation

Example of location services

The table below lists the attributes of specific location based services as determined

by the GSM Alliance Services Working Group. It is possible for the network operator

or service provider to define additional, non-standardised service types.

Location based services categories Standardized Service Types

Public Safety Services Emergency Services

Emergency Alert Services

Location Sensitive Charging

Tracking Services Person Tracking

Fleet Management

Asset Management

Traffic Monitoring Traffic Congestion Reporting

Enhanced Call Routing Roadside Assistance

Routing to Nearest Commercial Enterprise

Location Based Information Service Navigation

City Sightseeing

Localized Advertising

Mobile Yellow Pages

Service Provider Specific Services

Standardized Service Types

UE locations is reported periodically. The periodic reporting function is generally

applicable for asset management services and exists as several variants, each

applicable to different value added services:

Location reporting only within predetermined

period e.g. commercial asset tracking and, subject to

provision of privacy, manpower planning.

Periodic location reporting within specified

period and reporting triggered by a specific

event

e.g. high value asset security, stolen vehicle

monitoring, home zone charging.

Periodic location reporting triggered by a

specific event e.g. 24hr depot management, transit

passenger information systems

A LCS Client is a logical functional entity that makes a request to the PLMN LCS

server for the location information of one or more than one target UEs. A LCS server

consists of a number of location service components and bearers needed to serve the

LCS clients. The LCS server shall provide a platform which will enable the support of

location based services in parallel to other telecommunication services such as speech,

data, messaging, other teleservices, user applications and supplementary services.

Using the Location Service Request, an LCS client communicates with the LCS

server to request the location information for one or more target UEs within a

specified set of quality of service parameters. As shown in below, a location service

may be specified as immediate or deferred.

Request

Type Response Time

Number of

Responses

Immediate Immediate Single

Deferred Delayed (event

driven) One or More

Location Service Requests

The LCS Server will provide, on request, the current or most recent Location

Information (if available) of the Target UE or, if positioning fails, an error indication

plus optional reason for the failure.

For emergency services (where required by local regulatory requirements), the

geographic location may be provided to an emergency services LCS Client either

without any request from the client at certain points in an emergency services call

(e.g. following receipt of the emergency call request, when the call is answered, when

the call is released) or following an explicit request from the client. The former type

of provision is referred to as a “push” while the latter is known as a “pull”.

Type of Access Information Items

Push

Current Geographic Location (if available)

MSISDN

IMSI

IMEI

NA-ESRK

NA-ESRD

State of emergency call:

– unanswered, answered, released

Pull Geographic location, either:

- Current location

- Initial location at start of emergency call

Location information that may be provided

The specification Release '99 specifies the following LCS positioning methods:

• Cell coverage based positioning method

• Observed Time Difference Of Arrival (OTDOA) method with network

configurable idle periods

• Network assisted GPS methods

OTDOA Location Method

UMTS Power Control

Open loop power control is the ability of the UE transmitter to sets its output power

to a specific value. It is used for setting initial uplink and downlink transmission

powers when a UE is accessing the network. The open loop power control tolerance is

± 9 dB (normal conditions) or ± 12 dB (extreme conditions)

Inner loop power control (also called fast closed loop power control) in the uplink

is the ability of the UE transmitter to adjust its output power in accordance with one

or more Transmit Power Control (TPC) commands received in the downlink, in order

to keep the received uplink Signal-to-Interference Ratio (SIR) at a given SIR target.

The UE transmitter is capable of changing the output power with a step size of 1, 2

and 3 dB, in the slot immediately after the TPC_cmd can be derived. Inner loop

power control frequency is 1500Hz.

The serving cells estimate SIR of the received uplink DPCH, generate TPC

commands (TPC_cmd) and transmit the commands once per slot according to the

following rule: if SIRest > SIRtarget then the TPC command to transmit is "0", while if

SIRest < SIRtarget then the TPC command to transmit is "1". Upon reception of one or

more TPC commands in a slot, the UE derives a single TPC command for each slot,

combining multiple TPC commands if more than one is received in a slot. Two

algorithms are supported by the UE for deriving a TPC_cmd. Which of these two

algorithms is used, is determined by a UE-specific higher-layer parameter,

"PowerControlAlgorithm".

Algorithm 1:

• The power control step is the change in the UE transmitter output power in

response to a single TPC command

Algorithm 2:

• If all five estimated TPC command are "down" the transmit power is reduced by 1

dB

• If all five estimated TPC command are "up" the transmit power is increased by 1

dB

• Otherwise the transmit power is not changed

Transmitter power control range

The transmit power of the downlink channels is determined by the network. The

power control step size can take four values: 0.5, 1, 1.5 or 2 dB. It is mandatory for

UTRAN to support step size of 1 dB, while support of other step sizes is optional. The

UE generates TPC commands to control the network transmit power and send them in

the TPC field of the uplink DPCCH. Upon receiving the TPC commands UTRAN

adjusts its downlink DPCCH/DPDCH power accordingly.

Outer loop power control is used to maintain the quality of communication at the

level of bearer service quality requirement, while using as low power as possible. The

uplink outer loop power control is responsible for setting a target SIR in the Node B

for each individual uplink inner loop power control. This target SIR is updated for

each UE according to the estimated uplink quality (BLock Error Ration, Bit Error

Ratio) for each Radio Resource Control connection. The downlink outer loop power

control is the ability of the UE receiver to converge to required link quality (BLER)

set by the network (RNC) in downlink.

Power control of the downlink common channels are determined by the network.

In general the ratio of the transmit power between different downlink channels is not

specified in 3GPP specifications and may change with time, even dynamically.

Additional special situations of power control are Power control in compressed

mode and Downlink power during handover.

Further reading: 3GPP TS 25.101, 25.133, 25.214, 25.215, 25.331, 25.433, 25.435,

25.841, 25.849

Cell search procedure

During the cell search, the UE searches for a cell and determines the downlink

scrambling code and frame synchronisation of that cell. The cell search is typically

carried out in three steps:

Step 1: Slot synchronisation

During the first step of the cell search procedure the UE uses the SCH's primary

synchronisation code to acquire slot synchronisation to a cell. This is typically done

with a single matched filter (or any similar device) matched 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.

Step 2: Frame synchronisation and code-group identification

During the second step of the cell search procedure, the UE uses the SCH's secondary

synchronisation code to find frame synchronisation and identify the code group of the

cell found in the first step. 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.

Step 3: Scrambling-code identification

During the third and last step of the cell search procedure, the UE determines the

exact primary scrambling code used by the found cell. The primary scrambling code

is typically identified through symbol-by-symbol correlation over the CPICH with all

codes within the code group identified in the second step. After the primary

scrambling code has been identified, the Primary CCPCH can be detected and the

system- and cell specific BCH information can be read.

If the UE has received information about which scrambling codes to search for, steps

2 and 3 above can be simplified

Structure of synchronization channel

The Synchronisation Channel (SCH) is a downlink signal used for cell search. The

SCH consists of two sub channels, the Primary and Secondary SCH. The 10 ms radio

frames of the Primary and Secondary SCH are divided into 15 slots, each of length

2560 chips. Picture above illustrates the structure of the SCH radio frame.

The Primary SCH consists of a modulated code of length 256 chips, the primary

synchronization code (PSC) is transmitted once every slot. The PSC is the same for

every cell in the system.

The Secondary SCH consists of repeatedly transmitting a length 15 sequence of

modulated codes of length 256 chips, the Secondary Synchronisation Codes (SSC),

transmitted in parallel with the Primary SCH. The SSC is denoted csi,k

in figure 20,

where i = 0, 1, …, 63 is the number of the scrambling code group, and k = 0, 1, …, 14

is the slot number. Each SSC is chosen from a set of 16 different codes of length 256.

This sequence on the Secondary SCH indicates which of the code groups the cell's

downlink scrambling code belongs to.

Summary of the process:

Channel Synchronisation

acquired Note

Primary Chip, Slot, Symbol 256 chips

SCH Synchronisation The same in all cells

Secondary

SCH

Frame

Synchronisation,

Code Group (one of

64)

15-code sequence of secondary

synchronisation codes.

There are 16 secondary synchronisation

codes.

There are 64 S-SCH sequences corresponding

to the 64 scrambling code groups

256 chips, different for different cells and slot

intervals

Common

Pilot CH

Scrambling code

(one of 8)

To find the primary scrambling code from

common pilot CH

PCCPCH *)

Super Frame

Synchronisation,

BCCH info

Fixed 30 kbps channel

27 kbps rate

spreading factor 256

SCCPCH **) Carries FACH and PCH channels

Variable bit rate

*) Primary Common Control Physical Channel

**) Secondary Common Control Physical Channel

Further reading: 3GPP TS 25.211 25.213

Random Access

The Random Access Channel (RACH) is an uplink transport channel. The RACH is

always received from the entire cell. The RACH is characterized by a collision risk

and by being transmitted using open loop power control.

RACH access slot numbers and their spacing

RACH preamble is of length 4096 chips and consists of 256 repetitions of a

signature of length 16 chips. There are a maximum of 16 available signatures. All 16

preamble signature codes available in every cells.

The 10 ms RACH message part radio frame is split into 15 slots, each of length Tslot

= 2560 chips. Each slot consists of two parts, a data part to which the RACH transport

channel is mapped and a control part that carries Layer 1 control information. The

data and control parts are transmitted in parallel. A 10 ms message part consists of

one message part radio frame, while a 20 ms message part consists of two consecutive

10 ms message part radio frames. The data part consists of 10*2k bits, where

k=0,1,2,3. This corresponds to a spreading factor of 256, 128, 64, and 32 respectively

for the message data part.

Structure of the random-access message part radio frame

The Acquisition Indicator Channel (AICH) is a fixed rate (SF=256) physical

channel used to carry Acquisition Indicators (AI). Acquisition Indicator AIs

corresponds to signature s on the PRACH.

Structure of Acquisition Indicator Channel

The Access Preamble Acquisition Indicator channel (AP-AICH) is a fixed rate

(SF=256) physical channel used to carry AP acquisition indicators (API) of CPCH.

AP acquisition indicator APIs corresponds to AP signature s transmitted by UE.

The Collision Detection Channel Assignment Indicator channel (CD/CA-ICH) is a

fixed rate (SF=256) physical channel used to carry CD Indicator (CDI) only if the CA

is not active, or CD Indicator/CA Indicator (CDI/CAI) at the same time if the CA is

active. The structure of CD/CA-ICH is shown in figure 25. CD/CA-ICH and AP-

AICH may use the same or different channelisation codes. The CD/CA-ICH has a part

of duration of 4096chips where the CDI/CAI is transmitted, followed by a part of

duration 1024chips with no transmission that is not formally part of the CD/CA-ICH.

The part of the slot with no transmission is reserved for possible use by CSICH or

possible future use by other physical channels.

Uplink Common Packet channel (CPCH) is an extension to the RACH channel for

packet-based user data.

PCPCH Access Example:

PCPCH (similar to RACH) and AICH transmission as seen by the UE

DPCCH

PCPCH

AP-AICH

CD/CA-ICH

AP

CD/CA

Dedicated Physical Control Channel

Physical Common Packet Channel

Access Preamble Acquisition Indicator Channel

Collision Detection/Channel Assignment Indicator Channel

Access Preamble

Collision Detection/Channel Assignment

Indicators are means of fast low-level signalling entities which are transmitted

without using information blocks sent over transport channels. The meaning of

indicators is specific to the type of indicator. The indicators defined in the current

version of the specifications are:

• Acquisition Indicator (AI)

• Access Preamble Indicator (API)

• Channel Assignment Indicator (CAI)

• Collision Detection Indicator (CDI)

• Page Indicator (PI)

• Status Indicator (SI)

Indicators may be either boolean (two-valued) or three-valued. Their mapping to

indicator channels is channel specific. Indicators are transmitted on those physical

channels that are indicator channels (ICH).


UMTS RCC States

Picture below shows the RRC states in UTRA RRC Connected Mode, including

transitions between UTRA RRC connected mode and GSM connected mode for CS

domain services, and between UTRA RRC connected mode and GSM/GPRS packet

modes for PS domain services. It also shows the transitions between Idle Mode and

UTRA RRC Connected Mode and furthermore the transitions within UTRA RRC

connected mode.

RRC States and State Transitions including GSM

CELL_DCH state is characterised by:

• A dedicated physical channel is allocated to the UE in uplink and downlink.

• The UE is known on cell level according to its current active set.

• Dedicated transport channels, downlink and uplink (TDD) shared transport

channels, and a combination of these transport channels can be used by the UE.

CELL_FACH state is characterised by:

• No dedicated physical channel is allocated to the UE.

• The UE continuously monitors a FACH in the downlink.

• The UE is assigned a default common or shared transport channel in the uplink (e.g.

RACH) that it can use anytime according to the access procedure for that transport

channel.

• The position of the UE is known by UTRAN on cell level according to the cell

where the UE last made a cell update.

• In TDD mode, one or several USCH or DSCH transport channels may have been

established.

CELL_PCH state is characterised by:

• No dedicated physical channel is allocated to the UE.

• The UE selects a PCH with the algorithm, and uses DRX for monitoring the

selected PCH via an associated PICH.

• No uplink activity is possible.

• The position of the UE is known by UTRAN on cell level according to the cell

where the UE last made a cell update in CELL_FACH state.

URA_PCH State is characterised by:

• No dedicated channel is allocated to the UE.

• The UE selects a PCH with the algorithm, and uses DRX for monitoring the

selected PCH via an associated PICH.

• No uplink activity is possible.

• The location of the UE is known on UTRAN Registration area level according to

the URA assigned to the UE during the last URA update in CELL_FACH state.

Call reselection procedures:

States and procedures in the cell reselection process in connected mode

When a cell reselection is triggered, the UE evaluates the cell reselection criteria

based on radio measurements, and if a better cell is found that cell is selected,

procedure Cell reselection. If the change of cell implies a change of radio access

technology, the RRC connection is released, and the UE enters idle mode of the other

RAT. If no suitable cell is found in the cell reselection procedure, the UE eventually

enters idle mode.

When an Initial cell reselection is triggered, the UE shall use the Initial cell

reselection procedure to find a suitable cell. One example where this procedure is

triggered is at radio link failure, where the UE may trigger an initial cell reselection in

order to request re-establishment of the RRC connection. If the UE is unable to find a

suitable cell, the UE eventually enters idle mode.


UTRAN Iub Interface General Frame Structure

The general structure of a Common Transport Channel frame between Node B and

RNC consists of a header and a payload.

Header Payload: Data or Control Information

General Frame Structure

There are two types of frames (indicated by the Frame Type field).

• Data frame.

• Control frame.

The general structure of frames

Data frame example:

DL FDD DSCH data frame structure

CRC

FT

CFN

TFI

SF

SP

MC Info

TB

Cyclic Redundancy Checksum

Frame Type

Connection Frame Number

Transport Format Indicator

Spreading Factor

Spare

Multi Code to indicate the number of parallel PDSCH codes

on which the DSCH data will be carried

Transport Block

Control frame example:

Iub Common Transport Channel Control Frame Format


Call Setup

Basic Mobile Originating Call Diagram

Further reading: 3GPP TS 25.303, 25.331

UTRAN Protocol Model

The general protocol model for UTRAN Interfaces is shown below. The structure is

based on the principle that the layers and planes are logically independent of each

other. Therefore, as and when required, the standardisation body can easily alter

protocol stacks and planes to fit future requirements.

General Protocol Model for UTRAN Interfaces

Horizontal Layers

The Protocol Structure consists of two main layers, Radio Network Layer, and

Transport Network Layer. All UTRAN related issues are visible only in the Radio

Network Layer, and the Transport Network Layer represents standard transport

technology that is selected to be used for UTRAN, but without any UTRAN specific

requirements.

Vertical Planes

The Control Plane Includes the Application Protocol, i.e. RANAP, RNSAP or

NBAP, and the Signalling Bearer for transporting the Application Protocol messages.

Among other things, the Application Protocol is used for setting up bearers for (i.e.

Radio Access Bearer or Radio Link) in the Radio Network Layer.

The User Plane Includes the Data Stream(s) and the Data Bearer(s) for the Data

Stream(s). The Data Stream(s) is/are characterised by one or more frame protocols

specified for that interface.

The Transport Network Control Plane does not include any Radio Network Layer

information, and is completely in the Transport Layer. It includes the ALCAP

protocol(s) that is/are needed to set up the transport bearers (Data Bearer) for the User

Plane. It also includes the appropriate Signalling Bearer(s) needed for the ALCAP

protocol(s).

The Transport Network Control Plane is a plane that acts between the Control

Plane and the User Plane. The introduction of Transport Network Control Plane is

performed in a way that the Application Protocol in the Radio Network Control Plane

is kept completely independent of the technology selected for Data Bearer in the User

Plane. Indeed, the decision to actually use an ALCAP protocol is completely kept

within the Transport Network Layer.

Iur Interface Protocol Structure

Iur layers

Further Reading:

Iur specification numbers

Protocol layering specification numbers

More further reading: 3GPP TS 25.401, 25.420

Paging

The Paging Channel (PCH) is a downlink transport channel. The PCH is always

transmitted over the entire cell. The transmission of the PCH is associated with the

transmission of physical-layer generated Paging Indicators, to support efficient sleep-

mode procedures.

Paging Channel selection

System information block type 5 (SIB 5) defines common channels to be employed in

Idle mode. In a cell, a single or several PCHs may be established. Each Secondary

Common Control Physical Channel (SCCPCH) indicated to the UE in system

information may carry up to one PCH. Thus, for each defined PCH there is one

uniquely associated PICH also indicated.

In case that more than a single PCH and associated PICH are defined in SIB 5, the UE

shall perform a selection according to the following rule:

• The UE shall select a SCCPCH from the ones listed in SIB 5 based on IMSI as

follows:

"Index of selected SCCPCH" = IMSI mod K,

where K is equal to the number of listed SCCPCHs which carry a PCH (i.e.

SCCPCHs carrying FACH only shall not be counted). These SCCPCHs shall be

indexed in the order of their occurrence in SIB 5 from 0 to K-1.

"Index of selected SCCPCH" identifies the selected SCCPCH with the PCH and the

uniquely associated PICH to be used by the UE. If the UE has no IMSI, for instance

when making an emergency call without USIM, the UE shall use as default number

IMSI = 0.

The UE may use Discontinuous Reception (DRX) in idle mode in order to reduce

power consumption. When DRX is used the UE needs only to monitor one Page

Indicator, PI, in one Paging Occasion per DRX cycle.

The Paging Indicator Channel (PICH) is a fixed rate (SF=256) physical channel

used to carry the paging indicators. The PICH is always associated with an S-CCPCH

to which a PCH transport channel is mapped. Picture below illustrates the frame

structure of the PICH. One PICH radio frame of length 10 ms consists of 300 bits. Of

these, 288 bits are used to carry paging indicators. The remaining 12 bits are not

formally part of the PICH and shall not be transmitted (DTX). The part of the frame

with no transmission is reserved for possible future use.

Structure of Paging Indicator Channel (PICH)

Two Paging Procedures:

Paging procedure is used to transmit paging information to selected UEs in idle mode,

CELL_PCH or URA_PCH state using the paging control channel (PCCH). Upper

layers in the network may request paging, to e.g. establish a signalling connection.

UTRAN may initiate paging for UEs in CELL_PCH or URA_PCH state to trigger a

cell update procedure. In addition, UTRAN may initiate paging for UEs in idle mode,

CELL_PCH and URA_PCH state to trigger reading of updated system information.

UTRAN initiates the paging procedure by transmitting a PAGING TYPE 1 message

on an appropriate paging occasion on the PCCH.

UE dedicated paging procedure is used to transmit dedicated paging information to

one UE in connected mode in CELL_DCH or CELL_FACH state. Upper layers in the

network may request initiation of paging. For a UE in CELL_DCH or CELL_FACH

state, UTRAN initiates the procedure by transmitting a PAGING TYPE 2 message on

the DCCH using AM RLC.

Two Paging Message Types:

PAGING TYPE 1 message is used to send information on the paging channel. One or

several UEs, in idle or connected mode, can be paged in one message, which also can

contain other information

PAGING TYPE 2 message is used to page an UE in connected mode (CELL_DCH or

CELL_FACH state), when using the DCCH for CN originated paging.

PICH / S-CCPCH timing relation

Picture below illustrates the timing between a PICH frame and its associated single S-

CCPCH frame, i.e. the S-CCPCH frame that carries the paging information related to

the paging indicators in the PICH frame. A paging indicator set in a PICH frame

means that the paging message is transmitted on the PCH in the S-CCPCH frame

starting tPICH chips after the transmitted PICH frame.

Timing relation between PICH frame and associated S-CCPCH frame

tPICH = 7680 chips (3 slots)

Paging Block Periodicity (PBP): Period of the occurrence of Paging Blocks. (For FDD, PBP = 1).

Paging occasion: (FDD) The SFN of the PICH frame where the UE monitors its paging indicator (i.e.

the SFN of the PCCPCH frame in which the PICH frame begins).

Further reading: 3GPP TS 25.211 25.304

Virtual Home Environment (VHE)

Virtual Home Environment (VHE) is a concept for Personal Service Environment

(PSE) portability across network boundaries and between terminals. The concept of

VHE is such that users are consistently presented with the same personalised features,

User Interface customisation and services in whatever network and whatever terminal

(within the capabilities of the terminal and the network), wherever the user may be

located. For Release 5, CAMEL, MExE, OSA and USAT are considered the

mechanisms supporting the VHE concept.

CAMEL Customised Application For Mobile Network Enhanced Logic

MExE Mobile Execution Environment

MRF Media Resource Function

OSA Open Service Access

USAT Universal SIM Application Tool-Kit

A user's VHE is enabled by user profiles as logically depicted in a picture below. The

home environment shall:

• enable the user to manage one or more user profiles (e.g. activate, modify,

deactivate etc.)

• enable the home environment and HE-VASP to manage one or more user profiles

(e.g. activate, modify, deactivate etc.)

• enable the identification of a user's personalised data and services information

directly or indirectly from the user's profile(s)

• enable authorised HE-VASPs to access the user's profile(s)

• enable VASPs controlled and limited access to the user's profile(s) (e.g. for general

user preferences and subscribed services information).

The home environment's view of the Virtual Home Environment concept is logically

depicted in a picture below. The home environment shall:

• be able to provide and control services to the user in a consistent manner also if the

user is roaming

• provide the necessary means to create and maintain a set of user profiles

• Support the execution of services – through its Service Toolkits in the network, the

USIM and in the ME

• uniquely identify the user in the telecommunication networks supported by the

Home Environment.

Logical VHE Role Model (Operator's Home Environment's View)

The Open Service Access consists of three parts:

• Applications: e.g. VPN, conferencing, location based applications. These

applications are implemented in one or more Application Servers;

• Framework: providing applications with basic mechanisms that enable them to

make use of the service capabilities in the network. Examples of framework functions

are Authentication and Discovery. The discovery function enables the application to

find out which network service capability features are provided by the Service

Capability Servers.

• Service Capability Servers: providing the applications with service capability

features, which are abstractions from underlying network functionality. Examples of

service capability features offered by the Service Capability Servers are Call Control

and User Location.

Mobile Execution Environment (MExE) provides a standardised execution

environment in an UE, and an ability to negotiate its supported capabilities with a

MExE service provider, allowing applications to be developed independently of any

UE platform. The UE (consisting of the ME and SIM/USIM) can then be targeted at a

range of implementations for MExE from small devices with low bandwidth, limited

displays, low processor speeds, limited memory, MMI etc., to sophisticated with a

complete MExE execution environment.

Generic MExE architecture

Universal Subscriber identity module Application Toolkit (USAT) provides a

standardised execution environment for applications stored on the USIM/SIM card

and the ability to utilize certain functions of the supporting mobile equipment.

SAT/USAT provides mechanisms which allow applications, existing in the

USIM/SIM, to interact and operate with any ME which supports the specified

mechanism(s) thus ensuring interoperability between a USIM/SIM and an ME,

independent of the respective manufacturers and operators. A transport mechanism is

provided enabling applications to be down-loaded and/or updated.

USAT Diagram

Further reading: 3GPP TS 22.121 22.038 22.057 23.057 23.078 23.127 23.955

3G

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