mobile comm ch1

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Mobile Communication System Introduction Cellular concept Large scale and small scale fading Analog cellular mobile system Digital cellular mobile system Low power wireless communication system CDMA digital cellular standard Mobile terminals Global mobile satellite system 3G systems

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Page 1: Mobile Comm Ch1

Mobile Communication System Introduction Cellular concept Large scale and small scale fading Analog cellular mobile system Digital cellular mobile system Low power wireless communication system CDMA digital cellular standard Mobile terminals Global mobile satellite system 3G systems

Page 2: Mobile Comm Ch1

Books

Wireless Communications Theodore S Rappaport

Mobile and Personal Communication Systems and Services Raj Pandya

Mobile Communication Engineering William CY Lee

Page 3: Mobile Comm Ch1

Termwork Evaluation

Attendance 05 marks Internal Tests 10 marks Journal 10 marks

8 Tutorials 2 Assignments Objective test

Page 4: Mobile Comm Ch1

Introduction

Underlying vision for mobile and PCS is to enable communication with a person At any time At any place (Reachability)

Home, office, in public, in transit In any form (Accessibility)

Cellular phone, office wired phone, Fax, PDA

Page 5: Mobile Comm Ch1

“Mobile” : Any radio terminal that could be moved during operation

Now Any radio terminal that is attached to a high speed

mobile platform Cellular telephones

“portable” : Any radio terminal that can be handheld and used by someone at walking speed

Cordless phones Walkie-talkies

Page 6: Mobile Comm Ch1

Limitations of conventional mobile systems

Limited service capability Used a single high powered transmitter with an antenna

mounted on a tall tower that lead to Large coverage area Limited assigned channels Frequency reuse was not possible

Limited number of active users at any given time

Poor service performance Limited number of channels

Limited number of active users at a time High blocking probability during busy hours

Page 7: Mobile Comm Ch1

Inefficient frequency spectrum utilization Frequency utilization measurement

Measures maximum no. of customers that can be served by one channel at busy hour

As number of customers increase Mo increases Blocking probability increases

channelsofNumber

customersofNumberM o __

__

Page 8: Mobile Comm Ch1

Mobile and PCS represent evolution and enhancements in many directions like

Increased capacity and coverage Global roaming and service delivery Interoperability between different radio environments Support of high bit rate data, internet and multimedia services Wireless-wireline integration for mobile broadband services Global coverage using satellite constellations

Rapid worldwide growth has demonstrated that wireless communication is a robust, viable voice and data transport technology

Page 9: Mobile Comm Ch1

Since the initial commercial introduction of Advanced

Mobile Phone System (AMPS), mobile radio communication has seen explosive growth fueled by

Digital and RF circuit fabrication improvements New large scale circuit integration Miniaturization technologies which makes portable radio

equipment smaller, cheaper and more reliable Digital switching techniques facilitating large scale deployment of

affordable, easy-to-use radio communication networks Frequency reuse capabilities Advances in digital signal processing techniques and integrated

circuit technology

Page 10: Mobile Comm Ch1

Systems have evolved to address a range of applications and markets which includes Digital cellular mobile Cordless telephony Satellite mobile systems Paging systems Walkie-talkies WLAN Bluetooth UWB systems

Page 11: Mobile Comm Ch1

Classified as Simplex

Paging systems Half-duplex

Walkie-talkies Duplex

Uses FDD/TDD Cordless telephony Cellular telephony

Page 12: Mobile Comm Ch1

Evolution

Standard Type Year MA Freq band Mod Ch BW

AMPS Cellular 1983 FDMA 824-894 MHz FM 30 kHz

NAMPS Cellular 1992 FDMA 824-894 MHz FM 10 kHz

USDC Cellular 1991 TDMA 824-894 MHz /4-DQPSK 30 kHz

IS-95 Cellular/ PCS

1993 CDMA (DSSS)

824-894 MHz QPSK/ BPSK

1.25 MHz

POCSAG Paging 1970’s Simplex Several FSK 12.5 kHz

PACS Cordless/ PCS

1994 TDMA/ FDMA

1.85-1.99GHz /4-DQPSK 300 kHz

Major Mobile Radio Standards in North America

Page 13: Mobile Comm Ch1

Standard Type Year MA Freq band Mod Ch BW

NTT Cellular 1979 FDMA 400/800 MHz FM 25 kHz

JTACS Cellular 1988 FDMA 860-925 MHz FM 25 kHz

PDC Cellular 1993 TDMA 810-1501 MHz

/4-DQPSK 25 kHz

NTACS Cellular 1993 FDMA 843-925 MHz FM 12.5 kHz

PHS Cordless 1993 TDMA 1895-1907 MHz

/4-DQPSK 300 MHz

NTT Paging 1979 FDMA 280 MHz FSK 12.5 kHz

Major Mobile Radio Standards in Japan

Page 14: Mobile Comm Ch1

Standard Type Year MA Freq band

Mod Ch BW

ETACS Cellular 1985 FDMA 900 MHz FM 25 kHz

GSM Cellular/ PCS

1990 TDMA 890-960 MHz

GMSK 200 kHz

CT2 Cordless 1989 FDMA 864-868 MHz

GFSK 100 kHz

DECT Cordless 1993 TDMA 1.88-1.9GHz

GFSK 1.728 MHz

Major Mobile Radio Standards in Europe

Page 15: Mobile Comm Ch1

GMPCS These are developed to complement cellular and

personal communication networks whose radio coverage is confined to populated areas

GMPCS systems like Iridium Globalstar Teledesic

operate as overlay networks for existing cellular and PCS networks

Page 16: Mobile Comm Ch1

Mobile generations First generation

Analog cellular mobile system FDMA/FM/FDD

Second generationprovides atleast 3 times increase in spectrum efficiency Digital cellular mobile system

TDMA/FDD CDMA/FDD

Low power wireless and PCS Rely on sophisticated DSP in handset and BS

Page 17: Mobile Comm Ch1

Popular second generation standards Three TDMA standards

GSM (Europe, Asia, Australia) IS-136 or NADC (North America) PDC (Japan)

One CDMA standard IS-95 or cdmaOne

These systems were developed to meet business and regulatory requirements in specific countries and/or regions leading to incompatible systems that are unable to provide global mobility

Page 18: Mobile Comm Ch1

2G networks only support single user data rates (10 kbps) which is too slow for rapid email and internet browsing applications

Evolution toward high data rate packet mode capabilities was a key requirement

Hence new data centric standards have been developed that can be overlaid upon existing 2G technologies

These represent 2.5G technology and allow existing 2G equipment to be modified and supplemented with new base station add-ons and subscriber unit software upgrades

Page 19: Mobile Comm Ch1

Upgradation to 2.5G 3 upgrade paths for GSM

High speed circuit switched data (HSCSD)

General packet radio service (GPRS)

Enhanced data rate for GSM evolution (EDGE)

Two of them also support IS-136 GPRS EDGE

1 upgrade path available for IS-95 IS-95B

Page 20: Mobile Comm Ch1

3-G Technology Aim

Consolidation of different wireless environments like cellular mobile, cordless telephony, satellite mobile services under a single standard

Ensuring global mobility in terms of global seamless roaming and delivery of services

Action ITU formulated a plan (IMT-2000) to implement a global

frequency band in 2000 MHz range 3G evolution for CDMA leads to cdma2000 Eventual 3G evolution for GSM, IS-136 and PDC leads to

W-CDMA or UMTS (under ETSI) which is based on network fundamentals of GSM as well as merged vision of GSM and IS-136 through EDGE

Page 21: Mobile Comm Ch1

Paging systems Message sent to a paging

subscriber via a paging system access number (toll free no.) with a telephone keypad or a modem

Issued message is called a page

Paging system then transmits page throughout service area using BS which broadcasts page on a radio carrier

Page 22: Mobile Comm Ch1

Classification based on their complexity and coverage area Simple paging system : 2-5km Wide area paging system

Consists of a network of telephone lines, BS transmitters and large radio towers that simultaneously broadcast (simulcasting)

Paging receivers are simple and inexpensive Application : to provide reliable communication

to subscribers wherever they are. Hence Requires large transmitter powers (kW) and low data

rates for max coverage from each BS

Page 23: Mobile Comm Ch1

Cordless Telephone Systems Uses radio to connect a

portable handset to a dedicated BS which is then connected to a dedicated telephone line with a specific telephone number on PSTN

Provides users with limited range and mobility

Page 24: Mobile Comm Ch1

Cellular Telephone Systems Provides wireless connection to PSTN for any

user located within the radio range of system Accomodates large number of users over a large

geographical area within a limited frequency spectrum

High capacity achieved by limiting coverage of each BS transmitter to a small geographical area called cell so that frequency reuse can be done

Sophisticated switching technique called handoff enables call to proceed uninterrupted when user moves from one cell to another

Page 25: Mobile Comm Ch1

Smaller the cell size More efficient spectrum

utilization (higher frequency reuse)

More system capacity Operational unit

comprises of MSC/ MTSO Base station Mobile station

Page 26: Mobile Comm Ch1

MTSO Acts as central switching office for calls to and from

PSTN Coordinates activities of all BS and connects entire

cellular system to PSTN Major functions

Call switching, routing and overall control Interface with PSTN Coordination and system management Subscriber registration and billing Control of subscriber location and hand-off Provision of services (Call redirection, Call barring)

Page 27: Mobile Comm Ch1

Base Station Transmits to and receives from all mobile phones within the area

of cell Interface between MTSO and mobile unit,ie connects

simultaneous mobile calls via telephone lines or microwave links to MSC

Consists of Control unit Radio channels Several transmitting and receiving antennas on tower

Mobile unit Consists of control unit, transceiver and antenna system May be mounted on a vehicle or used as a portable hand-held unit

Page 28: Mobile Comm Ch1

Communication between BS and mobile is defined by a standard Common Air interface (CAI) that specifies 4 different channels

Forward voice channel (FVC) Channels used for voice transmission from BS to MS

Reverse voice channel (RVC) Channels used for voice transmission from MS to BS

Forward control channel (FCC) and reverse control channel (RCC) Channels responsible for initiating mobile calls Involved in setting up a call and moving it to an unused voice channel Handles supervisory and data messages to facilitate automatic

channel changes and handoff instructions