3G Mobile Comm'n

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Version 1 Revision 0 O & M of GSM (Alcatel)

11 3 G MOBILE COMMUNICATION

11.1 INTRODUCTION Wireless Generations

What is IMT-2000

What IMT-2000 offers

Key features and objectives

Spectrum for IMT-2000

Technologies for IMT-2000

Migration paths

Future Trends

1946- 1960s 1980s 1990s 2000s

Appeared 1G 2G 3G

Analog Digital Digital

Multi Multi Unified

Standard Standard Standard

Terrestrial Terrestrial Terr. & Sat

11.2WIRELESS GENERATIONS1 G -analog (cellular revolution) only mobile voice services

2 G - digital (breaking digital barrier) -mostly for voice services & data delivery possible

3 G - Voice & data (breaking data barrier) Mainly for data services where voice services will

also be possible

Beyond 3G Wide band OFDM ?But surely higher data rates

11.3LIMITATIONS OF 2ND GENERATION SYSTEMS No Global standards

No common frequency band

Low information bit rates

Low voice quality

No support of Video

Various categories of systems to meet specific requirements

11.4THIRD GENERATION (3 G ) STANDARD International mobile telecom 2000. imt-2000

ITUs vision for third generation mobile system

a future standard in which a single inexpensive mobile terminal can truly provide

communications any time and any where

Provisioning of these services over wide range of user densities and coverage areas.(in-

building , urban , sub-urban, global)

Efficient use of radio spectrum consistent with providing service at acceptable costly.

IMT-2000 shall cover application areas presently provided by seperately systems i.e

cellular, cordless and paging etc.

BRBRAITT, Jabalpur, Issued in June-2007 1


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A high degree of commonality of design worldwide.

A modular structure which will allow the system to grow in size and complexity.

Single unified standard (data & multimedia services)

Anywhere, anytime communication

Across networks, across technologies, seamless operation using a small pocket terminalworldwide.

High speed access 144kb/s, 384 kb/s & 2mb/s fast wireless access to internet

Full motion videophone

Terrestrial & satellite components

Enhanced voice quality, ubiquitous coverage and enable operators to provide service at

reasonable cost

Increased network efficiency and capacity

New voice and data services and capabilities

An orderly evolution path from 2G to 3G systems to protect investments.

11.4.1IMT TECHNOLOGIESITU has finally narrowed down technology options to the following five:

1. IMT -DS (Direct Spread) : W-CDMA UTRA FDD

2. IMT -MC (Multi Carrier) : CDMA 2000

3. IMT-TC ( Time Code) : TD -SCDMA UTRA TDD

4. IMT -SC ( Single Carrier ) : UWC - 136

5. IMT-FT (Frequency Time) : DECT


IMT-DS IMT-MC IMT-TC IMT-SC IMT-FT

WCDMA CDMA20001X/3X

TDMACDMA FDMA

CDMA-TDD UWC-136 FDMA/TDMADECT

IMT-2000 TERRESTRIAL

RADIO INTERFACES


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11.4.2IMT-2000 HARMONIZATION IS ON-GOINGIMT standards development involves extensive collaboration between many different

organizations

Todays operators need seamless 2G 3G

Many Focus groups have been established by industry 2 G operators GSM ; CDG ,UWCC, DECT forum

3 G Groups UMTS Forum , OHG

Focus group for IP-based 3G architecture (3G. IP)

SDOs created 3G PP (Partnership Projects)SDO Standards Development

Organizations

11.5MIGRATION PATH While a multiplicity of 2G standards have been developed and deployed, the ITU wanted to

avoid a similar situation to develop for 3G.

Hence, the ITU Radio communication Sector (ITU-R) has elaborated on a framework for a

global set of 3G standards, which will facilitate global roaming by operating in a commoncore spectrum and providing migration path from all the major existing 2G technologies.

The major 2G Radio access networks are based on either CDMA One or GSM

technologies and different migration path is proposed for each of these technologies.


GSM GPRS EDGE

PDC

CdmaOne

TDMA

IS-136

TDMA/

GPRS

TDMA/

EDGE

Cdma 2000

W CDMA

IMT-2000

CPABLE SYSTEMS

2000 EVOLVED 2G

64-115 Kbps

TODAY 2G

19.2 Kbps

3G

115-384 Kbps 0.384-2 Mbps


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11.6EVOLUTION FROM GSM TO 3G

11.6.1GSM EVOLUTION

11.7EDGE (ENHANCED DATA FOR GSM EVOLUTION) Next step towards 3G for GSM/GPRS Networks

Increased data rated up to 384 Kbps by bundling up to 8 channels of 48 Kbps/channel

GPRS is based on modulation technique known as GMSK

EDGE is based on a new modulation scheme that allows a much higher bit rate across the

air-interface called 8PSK modulation.

Since 8PSK will be used for UMTS, network operators will be required to introduce this at

some stage before migration to 3G.


GSM

2G

HSCSD

GPRS

2.5G

EDGE

3G

GPRS

200 KHz carrier

115 Kbps peak data rates

EDGE

200 KHz carrier

Data rates up to 384 Kbps

8-PSK modulation

Higher symbol rate

UMTS

5 MHz carrier

2 Mbps peak data rates

New IMT-2000 2 GHz spectrum

GSM

200 KHz carrier

8 full-rate time slots

16 half-rate time slots

GSM GPRS EDGE UMTS

3G2.5G2G

HSCSD

HSCSD

Circuit-switched data

64 Kbps peak data rates


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11.7.1GSM TO UMTS

11.7.2GSM TO GPRS TO EDGE TO 3G GSM can be upgraded for higher data rate upto 115 Kbps through deploying GPRS

(General Packet Radio Service) network.This requires addition of two core modules

SGSN (Serving GPRS Service Node)

GGSN (Gateway GPRS Service Node)

GSM radio access network is connected to SGSN through suitable interfaces.

GPRS phase-II will support higher data rates up to 384 Kbps through incorporating EDGE

( Enhanced Data Rate for GSM Evolution).


Software

Upgrade0101001010

BSC Upgrade

New

Software

01010101

00

New Software

01010101

00

New Software0101001010

MSC

PSTN

BSC

BTS

SGSN

WWWEnterprise Network

VPN

IP

Backbone

GGSN

GPRS

Backbone

Newmodified

router

New

Equipment

BSC

New

Terminal

New cell sites

(in some cases)

ModemPool

BTS

3G

GGSN

W-CDMA

BSC

3G

SGSN

NewEquipment

& Software

W-CDMA

BTS

New

Terminal

Evolution To W-CDMA

GSM

MSCPSTN,

ISDNGSM

BTS

GSM

BSC

PDN,(e.g. Internet)

GPRS

Core

GPRS

Core

Gb

Integrated

UMTS Core

Integrated

UMTS CoreUMTS

BTSUMTS

BSC

UMTS Access Network

Iu-r

Gs

Iu

Iubis

Other

PLMNGSM Elements

UMTS Elements

Service

Creation/

Mgmt.


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11.7.3GSM TO 3G Further, to support data rates up to 2 Mbps, Third Generation radio access network (3G

RAN)

W-CDMA is deployed. 3G RAN is connected to GSM MSC for circuit oriented services

and to SGSN for packet oriented services (internet access). Therefore the migration path

can be represented as :

GSM GPRS W-CDMA.

11.8MIGRATION SUMMARIZED In terms of migration of major 2G system to 3G capabilities, there would finally be 3

modes of CDMA-based radio interfaces (MC-CDMA, W-CDMA and CDMA-TDD) and

two `TDMA based radio interfaces (UWC-136 and DECT).

Considerable work is being carried out in respect of W-CDMA and CDMA 2000

worldwide. All European countries are expected to deploy W-CDMA as they haveGSM based networks. While other countries such as Japan, Korea, USA etc. are likely to

use CDMA-2000 or W-CDMA.

11.9FUTURE TRENDS (3 G TO 4G ONWARDS)New data services, interactive TV and evolving Internet behavior will influence

mobile data usage. Long sessions in always-on mode will force a re-think of radio access

technology to achieve the required but not easy to attain capacity (Gbit/s/km) at low cost. The

ideas presented in this article can increase capacity by a factor of 500 with regard to expected

cellular deployments. Coverage will be based on large umbrella cells (3G, WiMAX) and

numerous Pico cells interconnected to provide the user with seamless high data rate (several

Mbs) sessions. Scalable and progressive deployments are possible while protecting the



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operators long-term investment. The 4G infrastructure operator will mix several technologies,

each of which has its optimal usage. The connection to one of them will result in a real-time

trade-off which will offer the user the best possible service. Some tools that genuinely improve

the users multimedia quality of experience (availability, response time, definition, etc) are also

presented in this article.11.10 4G MOBILE

4G will deliver low cost multi-megabit/s sessions any time, any place, using any terminal.

11.10.1 Operational ExcellenceVoice was the driver for second generation mobile and has been a considerable success.

Today, video and TV services are driving forward third generation (3G) deployment and in the

future, low cost, high speed data will drive forward the fourth generation (4G) as short-range

communication emerges. Service and application ubiquity, with a high degree of

personalization and synchronization between various user appliances, will be another driver. At

the same time, it is probable that the radio

access network will evolve from a central-ized architecture to a distributed one.

11.10.2 Service EvolutionThe evolution from 3G to 4G will be driven by services that offer better quality (e.g.

video and sound) thanks to greater bandwidth, more sophistication in the association of a large

quantity of information, and improved personalization. Convergence with other network

(enterprise,fixed) services will come about through the high session data rate. It will require an

always-on connection and a revenue model based on a fixed monthly fee. The impact on

network capacity is expected to be significant. Machine-to-machine transmission will involve

two basic equipment types: sensors (which measure parameters) and tags (which are generally

read/write equipment). It is expected that users will require high data rates, similar to those on

fixed networks, for data and streaming applications. Mobile terminal usage (laptops, Personal

digital assistants, hand-helds) is expected to grow rapidly as they become more user friendly.Fluid high quality video and network reactivity are important user requirements. Key

infrastructure design requirements include: fast response, high session rate, high capacity, low

user charges, rapid return on investment for operators, investment that is in line with the growth

in demand, and simple autonomous terminals. The infrastructure will be much more distributed

than in current deployments, facilitating the introduction of a new source of local traffic:

machine-to-machine. Figure 1 shows one vision of how services are likely to evolve; mostsuch visions are similar. Dimensioning targets A simple calculation illustrates the order of

magnitude. The design target in terms of radio performance is to achieve a scalable capacity

from 50 to 500 bit/s/Hz/km 2 (including capacity for indoor use), as shown in Figure 2. As acomparison, the expected best performance of 3G is around 10 bit/s/Hz/km2 using High Speed

Down link Packet Access (HSDPA), Multiple-Input Multiple-Output (MIMO), etc. No currenttechnology is capable of such performance. Dimensioning objectives Based on various traffic

analyses, the Wireless World Initiative (WWI) has issued target air interface performance

figures. A consensus has been reached around peak rates of 100 Mbit/s in mobile situations and

1 Gbit/s in nomadic and pedestrian situations, at least as targets. So far, in a 10 MHz spec-trum,

a carrier rate of 20 Mbit/s has been achieved when the user is moving at high speed, and 40

Mbit/s in nomadic use. These values will double when MIMO is introduced. Clearly, the bit

rate should be associated with an amount of spectrum. For mobile use, a good target is a

network performance of 5 bit/s/Hz, rising to 8 bit/s/Hz in nomadic use.



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Figure 1

Figure 2:Dimensioning examples

11.10.3 Multi-Technology ApproachMany technologies are competing on the road to 4G, as can be seen in Figure 3. Three

paths are possible, even if they are more or less specialized. The first is the 3G-centric path, in

which Code Division Multiple Access (CDMA) will be progressively pushed to the point atwhich terminal manufacturers will give up. When this point is reached, another technology will

be needed to realize the requi-red increases in capacity and data rates. The second path is the

radio LAN one. Wide-spread deployment of WiFi is expected to start in 2005 for PCs, laptops

and PDAs. In enterprises, voice may start to be car-ried by Voice over Wireless LAN

(VoWLAN). However, it is not clear what the next successful technology will be. Reaching a

consensus on a 200 Mbit/s (and more) technology will be a lengthy task, with too many

proprietary solutions on offer. A third path is IEEE 802.16e and 802.20, which are simpler than

3G for the equivalent performance. A core network evolution towards a broadband Next

Generation Network (NGN) will facilitate the introduction of new access network technologies

through standard access gateways, based on ETSI-TISPAN, ITU-T, 3GPP, China



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Communication Standards Association (CCSA) and other standards. How can an operator

provide a large number of users with high session data rates using its existing infrastructure? At

least two technologies are needed. The first (called parent coverage) is dedicated to large

coverage and real-time services. Legacy technologies, such as 2G/3G and their evolutions will

be complemented by WiFi and WiMAX. A second set of technologies is needed to increasecapacity, and can be designed without any constraints on coverage continuity. This is known as

picocell coverage. Only the use of both technologies can achieve both targets (Figure 4).Handover between parent coverage and pico cell coverage is different from a classical roaming

process, but similar to classical handover. Parent coverage can also be used as a back-up when

service delivery in the pico cell becomes too difficult.

11.11 Key 4G TechnologiesSome of the key technologies required for 4G are briefly described below:

11.11.1 OFDMAOrthogonal Frequency Division Multiplexing (OFDM) not only provides clear advantages for

physical layer performance, but also a framework for improving layer 2 performance by

proposing an additional degree of freedom (Pico cell).A good example of a pico cellis a WiFi coverage. By extension, a pico cell has a radius around 50 m andthe associated base station is similar to a WiFi access point. It can bedeployed indoors or outdoors.



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Figure 4:Coverage performance trends

Using ODFM, it is possible to exploit the time domain, the space domain, the

frequency domain and even the code domain to optimize radio channel usage. It ensures very

robust transmission in multi-path environments with reduced receiver com-plexity. As shown

in Figure 5, the signal is split into orthogonal sub carriers, on each of which the signal isnarrow band (a few kHz) and therefore immune to multi-path effects, provided a guard

interval is inserted between each OFDM symbol. OFDM also provides a frequency diversitygain, improving the physical layer performance. It is also compatible with other enhancement

technologies, such as smart antennas and MIMO. OFDM modulation can also be employed as a

multiple access technology (Orthogonal Frequency Division Multiple Access; OFDMA). In

this case, each OFDM symbol can transmit information to/from several users using a different

set of subcarriers (subchannels). This not only provides additional flexibility for resource

allocation (increasing the capacity), but also enables cross-layer optimization of radio link

usage.

11.11.2 Software Defined RadioSoftware Defined Radio (SDR) benefits from todays high processing power to develop

multi-band, multi-standard base stations and terminals. Although in future the terminals will

adapt the air interface to the available radio access technology, at present this is done by the



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infra-structure. Several infrastructure gains are expected from SDR. For example, to increase

network capacity at a specific time (e.g. during

a sports event), an operator will reconfigure its net-work adding several modems at a given

Base Transceiver Station (BTS). SDR makes this reconfiguration easy. In the context of 4G

systems, SDR will become an enabler for the aggregation of multi-standard pico/micro cells.For a manufacturer, this can be a powerful aid to providing multi-standard, multi-band

equipment with reduced development effort and costs through simultaneous multi-channel

processing.

11.11.3 Multiple-Input Multiple-OutputMIMO uses signal multiplexing between multiple transmitting antennas (space

multiplex) and time or frequency. It is well suited to OFDM, as it is possible to process

independent time symbols as soon as the OFDM waveform is correctly designed for the

channel. This aspect of OFDM greatly simplifies processing. The signal transmitted by mantennas is received by n antennas. Processing of the received signals may deliver several

performance improvements: range, quality of received signal and spectrum efficiency. In

principle, MIMO is more efficient when many multiple path signals are received. Theperformance in cellular deployments is still subject to research and simulations. However, it is

generally admitted that the gain in spectrum efficiency is directly related to the minimum

number of antennas in the link.

11.11.4 Software Defined RadioSoftware Defined Radio (SDR) benefits from todays high processing power to develop

multi-band, multi-standard base stations and terminals. Although in future the terminals will

adapt the air interface to the available radio access technology, at present this is done by the

infra-structure. Several infrastructure gains are expected from SDR. For example, to increase

network capacity at a specific time (e.g. during

a sports event), an operator will reconfigure its net-work adding several modems at a given

Base Transceiver Station (BTS). SDR makes this reconfiguration easy. In the context of 4G

systems, SDR will become an enabler for the aggregation of multi-standard pico/micro cells.

For a manufacturer, this can be a powerful aid to providing multi-standard, multi-band

equipment with reduced development effort and costs through simultaneous multi-channel

processing.

11.11.5 Multiple-Input Multiple-OutputMIMO uses signal multiplexing between multiple transmitting antennas (space

multiplex) and time or frequency. It is well suited to OFDM, as it is possible to process

independent time symbols as soon as the OFDM waveform is correctly designed for the

channel. This aspect of OFDM greatly simplifies processing. The signal transmitted by mantennas is received by n antennas. Processing of the received signals may deliver several

performance improvements: range, quality of received signal and spectrum efficiency. In

principle, MIMO is more efficient when many multiple path signals are received. The

performance in cellular deployments is still subject to research and simulations . However, it is

generally admitted that the gain in spectrum efficiency is directly related to the minimum

number of antennas in the link.

11.11.6 Interlayer OptimizationThe most obvious interaction is the one between MIMO and the MAC layer. Other interactions

have been identified



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11.11.7 Handover and MobilityHandover technologies based on mobile IP technology have been considered for data

and voice. Mobile IP techniques are slow but can be accelerated with classical methods

(hierarchical, fast mobile IP). These methods are applicable to data and probably also voice. In

single-frequency networks, it is necessary to reconsider the handover methods. Severaltechniques can be used when the carrier to interference ratio is negative (e.g. VSF-OFDM, bit

repetition), but the drawback of these techniques is capacity. In OFDM, the same alternative

exists as in CDMA, which is to use macro-diversity. In the case of OFDM, MIMO allows

macro-diversity processing with performance gains. However, the implementation of macro-

diversity implies that MIMO processing is centralized and transmissions are synchronous. This

is not as complex as in CDMA, but such a technique should only be used in situations where

spectrum is very scarce.

Figure 5:OFDM principles

11.11.8 Caching and Pico CellsMemory in the network and terminals facilitates service delivery. In cellular systems,

this extends the capabilities of the MAC scheduler, as it facilitates the delivery of real-time

services. Resources can be assigned to data only when the radio conditions are favorable. This

method can double the capacity of a classical cellular system. In Pico cellular coverage, high

data rate (non-real-time) services can be delivered even when reception/transmission is

interrupted for a few seconds. Consequently, the coverage zone within which data can bereceived/transmitted can be designed with no constraints other than limiting interference. Data

delivery is preferred in places where the bit rate is a maximum. Between these areas, the

coverage is not used most of the time, creating an apparent discontinuity. In these areas,

content is sent to the terminal cache at the high data rate and read at the service rate. Coverages

are discontinuous. The advantage of coverage, especially when designed with caching

technology, is high spectrum efficiency, high scalability (from 50 to 500 bit/s/Hz), high

capacity and lower cost. A specific architecture is needed to intro-duce cache memory in the

net-work. An example is shown in Figure 8. At the entrance of the access network, lines ofcache at the destination of a terminal are built and stored. When a terminal enters an area in

which a transfer is possible, it simply asks for the line of cache following the last received.



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Between the terminal and the cache. A simple, robust and reliable protocol is used between the

terminal and the cache for every service delivered in this type of coverage.

11.11.9 Multimedia Service Delivery, Service Adaptation and Robust

TransmissionAudio and video coding are scalable. For instance, a video flow can be split into three

flows which can be transported independently: one base layer (30 kbit/s), which is a robust

flow but of limited quality (e.g. 5 images/s), and two enhancement flows (50 kbs and 200 kbs).The first flow provides availability, the other two quality and definition. In a streaming

situation, the terminal will have three caches. In Pico cellular coverage, the parent coverage

establishes the service dialog and service start-up (with the base layer). As soon as the terminal

enters pico cell coverage, the terminal caches are filled, starting with the base cache. Video

(and audio) transmissions are cur-rently transmitted without error and without packet loss.

However, it is possible to allow error rates of about 10 -5 /10 6 and a packet loss around 10 2 /10

-3 . Coded images still contain enough redundancy for error correction. It is possible to gain

about 10 dB in transmission with a reasonable increase in complexity. Using the described

technologies, multimedia transmission can provide a good quality user experience.



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11.11.10 CoverageCoverage is achieved by adding new technologies (possibly in overlay mode) and

progressively enhancing density. Take a WiMAX deployment, for example: first the parent

coverage is deployed; it is then made denser by adding discontinuous Pico cells, after which the

Pico cell is made denser but still discontinuously. Finally the pico cell cover-age is madecontinuous either by using MIMO or by deploying another Pico cell coverage in a different

frequency band .Parent coverage performance may vary from 1 to 20 bit/s/Hz/km?, while Pico

cell technology can achieve from 100 to 500 bit/s/Hz/km?, depending on the complexity of the

terminal hardware and software. These performances only refer to outdoor coverage; not all the

issues associated with indoor coverage have yet been resolved. However, indoor coverage can

be obtained by:

Direct penetration; this is only possible in low frequency bands (significantly below 1GHz) and requires an excess of power, which may raise significant interference issues.

Indoor short range radio connected to the fixed network. Connection via a relayto a Pico cellular access point.

11.11.11 Integration in a Broadband NGNThe focus is now on deploying an architecture realizing convergence between the fixed and

mobile networks (ITU-T Broad-band NGN and ETSI- TISPAN). This generic architecture

integrates all service enablers (e.g. IMS, network selection, middle ware for applications

providers), and offers a unique inter-face to application service providers.

11.12 ConclusionThe provision of megabit/s data rates to thousands of radio and mobile terminals per square

kilometer presents several challenges. Some key technologies permit the progressive

introduction of such networks without jeopardizing existing investment. Disruptive

technologies are needed to achieve high capacity at low cost, but it can still be done in a

progressive manner. The key enablers are: Sufficient spectrum, with associated sharing mechanisms.

Coverage with two technologies: parent (2G, 3G, WiMAX) for real-time delivery,

and discontinuous Pico cell for high data rate delivery.

Caching technology in the network and terminals.

OFDM and MIMO.

IP mobility.

Multi-technology distributed architecture.

Fixed-mobile convergence (for indoor service).

Network selection mechanisms.

Many other features, such as robust transmission and cross-layer optimization, will

contribute to optimizing the performance, which can reach between 100 and 500 bit/s/Hz/kmThe distributed, full IP architecture can be deployed using two main products: base stations and

the associated controllers. Terminal complexity depends on the number of technologies they

can work with. The minimum number of technologies is two: one for the radio coverage and

one for short range use (e.g. PANs). However, the presence of legacy networks will increase

this to six or seven.

Distributed architecture.

Architecture with a large number of decentralized connections to the core network.


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