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‘Digital Cellular Network Technologies’ An Overview National-Level Faculty Development Workshop “Challenges for Research in Wireless Communication Technologies” May 21-23, 2012 Chitkara University, Punjab Presented by Prof. T. L. Singal 1

Digital Cellular Network Technology

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Page 1: Digital Cellular Network Technology

‘Digital Cellular Network Technologies’

An Overview

National-Level Faculty Development Workshop

“Challenges for Research in Wireless Communication Technologies”

May 21-23, 2012

Chitkara University, Punjab

Presented by

Prof. T. L. Singal

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Evolution of Cellular Generations – A Recap

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Cellular Network Generations

• 1G: First Generation Analog Cellular System - Analog voice

• 2G: First Digital Cellular System

- Digital voice and messaging

• 2.5 G: Digital Cellular System

- Increase in digital data rates

• 3G: Digital Cellular System with increase in functionality - Broadband data and Voice over IP

• 4G: Future re-architecting of digital cellular infrastructure - Increased data throughput 3

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Examples of 1G and 2G

• First Generation Cellular Networks (1G)

– Analog systems based on FDMA (e.g. AMPS, NMT, UK-TACS)

• Second Generation Cellular Networks (2G)

– Digital systems based on TDMA and CDMA (e.g. GSM, TIA/EIA-136, IS-95)

• Second Generation+ Cellular Networks (2.5G)

– Digital systems based on TDMA and CDMA with higher data rate capabilities (e.g. GPRS, cdma2000)

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Advantages/Disadvantages -

1G and 2G Networks

• First Generation Cellular Networks (1G)

– Spotty coverage

• Second Generation Wireless (2G)

– Improved voice quality

– Limited low-speed, circuit-switched data capabilities

• Second Generation Wireless + (2.5G)

– Introduction of packet data

– Higher data rates (up to 144 kbps) 5

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3G and 4G

• Third Generation Cellular Networks (3G)

– Digital systems based on TDMA (GSM) and CDMA with data rate capability upto 2 Mbps (e.g. WCDMA/UMTS, cdma2000, UWC-136)

• Fourth Generation Cellular Networks (4G)

– Digital systems based on OFDMA and MC-CDMA with higher data rate capability for advanced multimedia applications.

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Evolution of Cellular Networks

Fourth Generation

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Key Parameters

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Paradigm shift - 1G towards 4G

Fourth Generation

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Comparison of 1G to 4G Systems

OFDMA,

MC-CDMA

Generation 1G 2G 3G 4G

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GSM and CDMA

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Multiple Access

Technologies

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GSM - FDMA and TDMA

1 2 3 4 5 6 ARFCN

Frequency

Amplitude

Time

0

1

2

3

4

5

6

7

time slot number

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GSM carriers are spaced 200

KHz apart.

In the BTS downlink signal,

different timeslots belong to

different users - a mobile

listens only to its recurring

timeslots.

The mobile on its uplink

transmits only during its

assigned timeslots.

Structure of a GSM Signal

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GSM Network Areas

Cells

Location

Areas

MSC/VLR

service areas

PLMN service area

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GSM Cell Plan

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GSM Network Architecture

NMC

Interface to other

networks

MS

M

S

BTS

BTS

BTS

BSS

BSS MSC MSC

MSC MSC

VLR

VLR

HLR

EIR

AuC

OMC OMC BSC

BTS

BTS

BTS

BSC

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A Typical GSM System

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Advantages/Disadvantages

- GSM Network • Advantages

– Can provide roaming services

– Reduces probability of total corruption of speech

– Offers standard protocols between components

• Disadvantages

– Limited data rate capability

– Macrocells affected by multipath signal loss

– Low Capacity 19

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GSM Networks Future Trends

GSM

Data

HSCSD

GPRS

EDGE

EGPRS

WCDMA

1999 2000 2002

WCDMA

Phase I

Evolution

9.6 kbps

9.6 - 28.8 kbps

9 - 53.6 kbps

<470 kbps

144 - 384 kbps

384 - 2048 kbps

2001 2003-2005

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What is CDMA?

Code Division Multiple Access

CDMA is a spread spectrum system and is directly related to

the number of users accessing the system.

CDMA system allow one-cell frequency reuse and all users

use the entire carrier, all the time. Each user is distinguished

by a Direct Sequence Code during a call.

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CDMA: Using A New Dimension

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CDMA is a Spread- Spectrum System

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CDMA Cell Plan

1

1

1

1

1

1

1

1

1

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CDMA Network Architecture

Interface to other

networks

MS

MS

BTS

BTS

BTS

BS

BS MSC MSC

MSC MSC

VLR

VLR

HLR

EIR

AuC

OS

BSC

BTS

BTS

BTS

BSC

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• Easy frequency planning (Frequency reuse of one)

• Greater coverage with fewer cells

• High capacity without hard blocking limits

• Excellent call quality (supports soft handoff)

• Inherent privacy due to unique user codes

• Lower power transmission

• Longer battery life

• Tight power control

• Technology platform extendable to new services

• Providing reliable transport mechanism for data communications, such as facsimile and internet traffic

CDMA - Advantages

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CDMA - Advantages contd…

Dramatically improving the telephone traffic capacity.

Significantly improving the voice quality and eliminating

the audible effects of multipath fading.

Reducing the incidence of dropped calls due to handoff

failures.

Reducing the number of sites needed to support any

given amount of traffic.

Simplifying site selection, thus reducing deployment and

operating costs because fewer cell sites are needed.

Reducing average transmitted power, thereby reducing

interference. 27

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Capacity Comparisons

– GSM and CDMA

GSM Capacity limit is fixed

at 8 x number of ARFCNs

per cell

CDMA Capacity limit is

„soft‟, Increases with

decrease in quality.

Typically 4-5 times that of

a GSM system. 28

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GSM

Architecture

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2G+ Cellular Network

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3G Market Drivers

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How Do Operators Get to 3G?

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3G air interface technologies

WCDMA/UMTS cdma2000 UWC-136

CDMA-based CDMA-based TDMA-based

Direct sequence Multi-carrier --

Evolution of GSM Evolution of

IS-95

Evolution of

TDMA

Requires new

spectrum

Could be

deployed in

existing spectrum

Could be

deployed in

existing spectrum 35

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GPRS Architecture

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Example for packet

routing in GPRS

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Example of GPRS Internet

Connection

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The GSM Technology Path to 3G

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3 Steps to 3G:

The GSM Network Transition

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GSM Network

ANSI-136 Network

ANSI-136 GSM

IW MAP IW ANSI-41

EGPRS

UWC-136/EDGE

TCP/IP

Network

Mobility Gateway

Global TDMA Convergence

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The CDMA Technology Path to 3G

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3G Network Architecture

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Advantages – The 3G Network

• Common worldwide spectrum

• Global seamless roaming

• Multimedia services on the mobile internet

• Flexible, spectrum-efficient network

• Enhanced security and performance

• Wireline services and quality levels

• Rapid introduction of new technology

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Disadvantages – The 3G Network

• Insufficient bandwidth

• Service differentiation

• IP translators are the wrong application and

service model (e.g., WAP, imode, etc.)

• Wrong architectural model for IP data

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KEY APPLICATIONS

• Current: ~10 kb/s, circuit/packet

– Fax

– Short-messaging

– Being evolved to ~50-100 kb/s peak rate

• Needed to make wireless data attractive:

– Web Browsing - downlink bandwidth hungry

– FTP or Emails with file attachment - both links

• 3G: “Multimedia,” mainly packet

– Wide-area, low mobility, 384 kb/s

– Wide-area, high mobility, 144 kb/s

– Indoor, 2 Mb/s

• Beyond 3G ?

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Radio Technology Evolution

• High Speed Services

– Nominal Rates:

• At least 144 kbps macrocell

• At least 384 kbps outdoor pedestrian

• At least 2 Mbps indoor

• => 1-2 Mbps or higher in macrocell

– Support emerging IP-based services

• Real-time and non real-time

– Optimized for packet-switched operation

• Support appropriate QoS definitions

• Data and multimedia services

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Technology Evolution to IMT-

2000 Radio Access

GSM

PDC

TDMA

(IS-136)

CDMA

(IS-95)

GSM+ GPRS

TDMA

IS-136+

CDMA 3G-1X

UWC-136 HS

(EDGE)

UMTS/

W-CDMA

EDGE/GPRS

cdma2000

IMT-2000

Systems

Existing

Spectrum New

Spectrum

?

?

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Deployment Scenario

GPRS

backbone

SGSN GGSN

GGSN

BG

Public

Internet

Backbone

router

router server

router

SGSN

Edge

Edge

GPRS

backbone

GGSN

GGSN BG

SGSN

WCDMA

Inter- operator

GPRS

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Wireless Data Terminals

Nokia 9110 Nokia

3G vision Sierra PCMCIA

CDPD Modem The new

Ericsson R380

phone, which

features wireless

data functions

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Looking to the Future….

4G and Beyond

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Transition from 3G to 4G ….

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Positions and Challenges for 4G

• Wireless Data is king

– Direction: design for data and IP - not voice circuits

• Wide variety of wireless link technologies; 2G/3G,

wireless LAN, MANETs, PANs, wireless sensor networks;

new radio 4G technologies will emerge

– Direction: IP over every radio link

• Multitude of mobile devices; sensors, watches, pagers,

pocket PCs, etc.

– Direction: IP on every mobile device 54

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Key Elements of 4G Vision

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• Fully converged services

Personal communications, information systems, broadcast,

entertainment and a wider range of services available conveniently,

securely and in a manner reflecting the user’s personal preferences.

• Ubiquitous mobile access

The dominant mode of access will be mobile, accounting for fully

converged services, including mobile access to commercial and

retail services.

• Diverse user devices

The user will be served by a wide variety of low-cost mobile devices

to access content conveniently and seamlessly. Devices will interact

with users in a multi-sensory manner. 56

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• Autonomous networks

4G systems will be highly autonomous adaptive networks capable of

self-management of their structure to meet users’ changing and

evolving demands, for both services and capacity. Efficient and cost-

effective use of the radio spectrum will be an essential element of their

operation.

• Software dependency

Intelligent Mobile Agents will exist throughout the networks and in

user devices, acting continually to simplify tasks and ensure

transparency to the user. These Mobile Agents will act at all levels,

from managing an individual user’s content preferences, to organizing

and reconfiguring major elements of networks.

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Advantages - The 4G Network

• Improved Spectral Efficiency

• Improved quality of service

• Increased data throughput

• Broadcast and Cellular Network Convergence

• Adaptive and Reconfigurable Systems

• Advanced Antenna Technologies

• Creation of new business models for operators

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4G Network Architecture

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4G Network Scenario

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4G Network Connectivity

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Vision of Beyond 4G

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Evolution from voice-only to

multimedia mobile services

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Ultimate Goal – Maximum Data Rate

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He executed international assignment as Senior Network Consultant with Flextronics International Inc. USA during 2000-02. He was associated with Nokia, AT&T, Cingular Wireless and Nortel Networks, for optimization of 2G/3G Cellular Networks in USA. Since 2003, he is in teaching profession in engineering colleges in India. He has number of technical research papers published in the IEEE Proceedings, Journals, and International/National Conferences. He has authored two text-books `Wireless Communications’ and `Analog & Digital Communications’, published by renowned publisher Tata McGraw-Hill.

T. L. Singal graduated from National Institute of

Technology, Kurukshetra in 1981 . He began his

illustrious career with Avionics Design Bureau at

HAL, Hyderabad and worked on design and

development of Air-Route Surveillance Radar

Communication System. Then he led R&D group in

a Telecom company and successfully developed

Multi-Access Wireless Communication Systems.

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References

T L Singal, Wireless Communications,

ISBN: 978-0-07-068178-1,

Tata McGraw-Hill, First Edition, 2010.

www.mhhe.com/singal/wc

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Queries?

[email protected]

Contact No: +91-98145-42041 67

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