Philadelphia UniversityFaculty of EngineeringCommunication and Electronics Engineering

Dr. Omar R Daoud ١

MOBILE COMMUNICATIONS (650539) Part 1

Dr. Omar R Daoud ٢

Text Book and References

T. Rappaport, “Wireless Communications: Principles and Practice”, 2nd

Edition, Prentice Hall, 2002.

W. Stalling, “Wireless Communications and Networks”, Pearson Education, 2002.

S. Haykin, “Communications Systems”, 4th

Edition, John Wiley and

Sons., 2001.

A. Yoshihiko, “Introduction to Digital Mobile Communication”, John Wiley and Sons., 1997.

L. William, “

Mobile Cellular Telecommunications: Analog and Digital Systems”, Mc Graw Hill, 1995.

Dr. Omar R Daoud ٣

Course Contents

Introduction (1 week)

Cellular Concepts, Coverage Principle and Frequency Reuse (2 weeks)

Multichannel and Cochannel Schemes (2 weeks)

Interference: Cochannel and Adjacent Channel (2 weeks)

Fading Models and Prediction of the Median Path Loss (2 weeks)

Modulation Techniques (2 weeks)

Mobile Communication Systems (2 weeks)

Private and Public Access Mobile Radio and Radio Paging (2 weeks)

Dr. Omar R Daoud ٤

Mode of Assessment

First Exam

(20%)

Second Exam (20%)

Quizzes\Reports\or Projects

(10%)

Final Exam

(50%)

Dr. Omar R Daoud ٥

Introduction

Mobile/ Wireless Systems Definitions

Why Cellular Mobile Systems?

Mobile Systems Revolutions

Dr. Omar R Daoud ٦

First Mobile Radio Telephone 1924

Dr. Omar R Daoud ٧

Mobile/ Wireless Systems Definitions

BS: Base Station; fixed station located on either the center or the edge of a coverage region. Consists of radio channels, transmitter and receivers antennas.

MS: a station which is intended for use while in motion at unspecified location.

Forward Channel/ downlink: The transmission process from BS to MS.

Reverse Channel/ uplink: The transmission process from MS to BS.

Handoff:

a process of automatically changing frequencies as the mobile unit moves into a different frequency zone. Thus, the call can be continued in a new frequency without redialing.

Full Duplex:

Transmission and reception on two different channels.

Half Duplex:

At any time the user can only transmit or receive information.

FDD: Frequency Division Duplexing; the radio transmission channels are provided simultaneously for the subscriber and the BS.

Dr. Omar R Daoud ٨

Mobile/ Wireless Systems Definitions

TDD: Time Division Duplexing; A single radio channel can be shared in time between the subscriber and the BS.

Roaming: a MS operate in a service area different than the from which service has been subscribed.

MSC: Mobile Switching Center; connects the BS and MS to the PSTN.

SSB: Single-sideband

FCC: Federal

Communications

Commission

MTS:

Mobile Telephone Service

IMTS:

Improved Mobile Telephone Service

AMPS:

Advanced Mobile Phone Service

TACS:

Total Access Communication System

NMT:

Nordic Mobile Telephone

Dr. Omar R Daoud ٩

Mobile/ Wireless Systems Definitions

GSM: Global System for Mobile Communications

PDC:

Personal Digital Cellular

HSCSD:

High Speed Circuit Switched Data

GPRS: General Packet Radio Service

EDGE:

Enhanced Data rates for Global Evolution

Dr. Omar R Daoud ١٠

Why Cellular Mobile Systems?

To Improve:* Service Capability* Service Performance * Frequency Spectrum Utilization

Dr. Omar R Daoud ١١

Why Cellular Mobile Systems?

Improving the Service Capability

In a conventional mobile telephone system: It is usually designed by selecting one or more channels from a specific frequency allocation for use in autonomous geographic zones.

Each zone is planned to be as large as possible (the transmitted power must be as high as the federal specifications allows).

The user must reinitiate the call when moving into a new zone because the call will be dropped.

The number of active users is limited to the number of channels assigned to a particular frequency zone.

Dr. Omar R Daoud ١٢

Why Cellular Mobile Systems?

Improving the Service PerformanceIn the conventional mobile telephone systems (MTS, IMTS-MJ and

IMTS-MK)

a total of 33 channels were allocated. The large number of subscribers created a high blocking probability during the busy hours. Thus a high-capacity systems were needed

Dr. Omar R Daoud ١٣

Why Cellular Mobile Systems?

Improving the Frequency Spectrum Utilization

In a conventional mobile telephone system the frequency utilization measurement is defined as the maximum number of subscribers that

could be served by one channel at the busy hour. In such systems the channel can only serve one customer at a time in a

whole area. Thus, a new cellular system must be initiated to overcome these

limitations. This systems must be:-

SSB: divides the allocated frequency band into maximum numbers of

channels-

Cellular: reuses the allocated frequency band in different geographical

locations-

Spread-spectrum or Frequency-hopped: generates many codes over a

wide frequency band

Dr. Omar R Daoud ١٤

1

2

3

4

5

6

7

1

2

3

4

5

6

7

572

2

11

2

3

4

5

6

7

3

Cellular Mobile Telephony

Frequency modulation

Antenna diversity

Cellular concept

Bell Labs (1957 & 1960)

Frequency reuse

Typically every 7 cells

Handoff as caller moves

Modified CO switch

HLR, paging, handoffs

Sectors improve reuse

Every 3 cells possible

Dr. Omar R Daoud ١٥

Mobile Systems Revolutions

1G (AMPS, TACS and NMT): Features:-Analogue systems -FM modulations-Cellular concepts-Hard Handoff

Dr. Omar R Daoud ١٦

First Generation

Advanced Mobile Phone Service (AMPS)

US trials 1978; deployed in Japan (’79) & US (’83)

800 MHz band —

two 20 MHz bands

TIA-553

Still widely used in US and many parts of the world

Nordic Mobile Telephony (NMT)

Sweden, Norway, Demark & Finland

Launched 1981; now largely retired

450 MHz; later at 900 MHz (NMT900)

Total Access Communications System (TACS)

British design; similar to AMPS; deployed 1985

Some TACS-900 systems still in use in Europe

Dr. Omar R Daoud ١٧

Mobile Systems Revolutions

2G (GSM, IS-95, PDC):Features:-Digital Mobile phones-Digital modulation -Data compression-Error control -Soft Handoff-SMS-High quality voice-More capacity/ each cell are divided among several users.

Dr. Omar R Daoud ١٨

Second Generation — 2G

There are a wide diversity of 2G systems

IS-54/ IS-136 North American TDMA; PDC (Japan)

iDEN

DECT and PHS

IS-95 CDMA (cdmaOne)

GSM

Dr. Omar R Daoud ١٩

D-AMPS/ TDMA & PDC

Speech coded as digital bit stream

Compression plus error protection bits

Aggressive compression limits voice quality

Time division multiple access (TDMA)

3 calls per radio channel using repeating time slices

Deployed 1993 (PDC 1994)

Development through 1980s; bakeoff 1987

IS-54 / IS-136 standards in US TIA

ATT Wireless & Cingular use IS-136 today

Plan to migrate to GSM and then to W-CDMA

PDC dominant cellular system in Japan today

NTT DoCoMo has largest PDC network

Dr. Omar R Daoud ٢٠

iDEN

Used by Nextel

Motorola proprietary system

Time division multiple access technology

Based on GSM architecture

800 MHz private mobile radio (PMR) spectrum

Just below 800 MHz cellular band

Special protocol supports fast “Push-to-Talk”

Digital replacement for old PMR services

Nextel has highest APRU in US market due to “Direct Connect”

push-to-talk service

Dr. Omar R Daoud ٢١

DECT and PHS

Also based on time division multiple access

Digital European Cordless Telephony

Focus on business use, i.e. wireless PBX

Very small cells; In building propagation issues

Wide bandwidth (32 kbps channels)

High-quality voice and/or ISDN data

Personal Handiphone

Service

Similar performance (32 kbps channels)

Deployed across Japanese cities (high pop. density)

4 channel base station uses one ISDN BRI line

Base stations on top of phone booths

Legacy in Japan; new deployments in China today

Dr. Omar R Daoud ٢٢

North American CDMA (cdmaOne)

Code Division Multiple Access

All users share same frequency band

Discussed in detail later as CDMA is basis for 3G

Qualcomm demo in 1989

Claimed improved capacity & simplified planning

First deployment in Hong Kong late 1994

Major success in Korea (1M subs by 1996)

Used by Verizon

and Sprint in US

Simplest 3G migration story today

Dr. Omar R Daoud ٢٣

cdmaOne — IS-95

TIA standard IS-95 (ANSI-95) in 1993

IS-95 deployed in the 800 MHz cellular band

J-STD-08 variant deployed in 1900 MHz US “PCS”

band

Evolution fixes bugs and adds data

IS-95A provides data rates up to 14.4 kbps

IS-95B provides rates up to 64 kbps (2.5G)

Both A and B are compatible with J-STD-08

All variants designed for TIA IS-41 core networks (ANSI 41)

Dr. Omar R Daoud ٢٤

GSM

«

Groupe

Special Mobile

», later

changed

to

«

Global System for Mobile

»

Joint European effort beginning in 1982

Focus on seamless roaming across Europe

Services launched 1991

Time division multiple access (8 users per 200KHz)

900 MHz band; later extended to 1800MHz

Added 1900 MHz (US PCS bands)

GSM is dominant world standard today

Well defined interfaces; many competitors

Network effect (Metcalfe’s law) took hold in late 1990s

Tri-band GSM phone can roam the world today

Dr. Omar R Daoud ٢٥

Mobile Systems Revolutions

2.5G (HSCSD,GPRS, EDGE):Features:2.5G is an interim solution designed to allow for

improved data rates prior to 3G implementation. A variety of 2.5G techniques are being employed to improve the speed of data for enhanced e-mail and Internet access.

Dr. Omar R Daoud ٢٦

Mobile Systems Revolutions

3G (UMTS, WCDMA):Features:

-Digital multimedia handset.

High data transmission rate > 100kbps.

Providing much more basic voice call.-Dynamic RRM.-Packet data.

Dr. Omar R Daoud ٢٧

3G Vision

Universal global roaming

Multimedia (voice, data & video)

Increased data rates

384 kbps while moving

2 Mbps when stationary at specific locations

Increased capacity (more spectrally efficient)

IP architecture

Dr. Omar R Daoud ٢٨

CDMA2000 Pros and Cons

Evolution from original Qualcomm CDMA

Now known as cdmaOne

or IS-95

Better migration story from 2G to 3G

cdmaOne

operators don’t need additional spectrum

1xEVD0 promises higher data rates than UMTS, i.e. W- CDMA

Better spectral efficiency than W-CDMA(?)

Arguable (and argued!)

CDMA2000 core network less mature

cmdaOne

interfaces were vendor-specific

Hopefully CDMA2000 vendors will comply w/ 3GPP2

Dr. Omar R Daoud ٢٩

W-CDMA (UMTS)

Wideband CDMA

Standard for Universal Mobile Telephone Service (UMTS)

Committed standard for Europe and likely migration path for other GSM operators

Leverages GSM’s

dominant position

Requires substantial new spectrum

5 MHz each way (symmetric)

Legally mandated in Europe and elsewhere

Sales of new spectrum completed in Europe

At prices that now seem exorbitant

Dr. Omar R Daoud ٣٠

TD-SCDMA

Time division duplex (TDD)

Chinese development

Will be deployed in China

Good match for asymmetrical traffic!

Single spectral band (1.6 MHz) possible

Costs relatively low

Handset smaller and may cost less

Power consumption lower

TDD has the highest spectrum efficiency

Power amplifiers must be very linear

Relatively hard to meet specifications

Dr. Omar R Daoud ٣١

CDMA

GSM

TDMA

PHS (IP-Based)

64 Kbps

GPRS

115 Kbps

CDMA 1xRTT

144 Kbps

EDGE

384 Kbps

cdma20001X-EV-DV

Over 2.4 Mbps

W-CDMA (UMTS)

Up to 2 Mbps

2G2.5G

2.75G 3G

1992 - 2000+2001+ 2003+

1G

1984 - 1996+

2003 - 2004+

TACS

NMT

AMPS

GSM/GPRS

(Overlay) 115 Kbps

9.6 Kbps

9.6 Kbps

14.4 Kbps/ 64 Kbps

9.6 Kbps

PDC

Analog Voice

Digital VoicePacket Data

IntermediateMultimedia

Multimedia

PHS

TD-SCDMA

2 Mbps?

9.6 Kbps

iDEN(Overlay)

iDEN

Source: U.S. Bancorp Piper Jaffray

Migration To 3G

Dr. Omar R Daoud ٣٢

Mobile Systems Revolutions

Dr. Omar R Daoud ٣٣

Mobile Wireless SpectrumBands Frequencies GSM/(MHz) (MHz) Regions EDGE WCDMA CDMA2000

450 450-467 Europe x x480 478-496 Europe x800 824-894 America x x900 880-960 Europe/APAC x x1500 Japan PDC x1700 1750-1870 Korea x1800 1710-1880 Europe/APAC x x x1900 1850-1990 America x x x

2100 1885-2025 & 2100-2200

Europe/APAC x x

2500 2500-2690 ITU Proposal x