Motivation & history moc

Elective III - Code: 414463 A Nitin S Ujgare 1

Motivation & History of Mobile Communication

Mobile ComputingProf. Nitin S UjgareDepartment of Information TechnologyNDMVPs KBTCOE , Nasik.


Outline

Motivation Introduction

What is Wireless Wireless Network

History of Wireless of Communication


Recommended Textbooks

Theodore Rappaport, Wireless Communications: Principles and Practice, Second Edition, Prentice Hall, December 2001.

Yi-Bing Lin, Imrich Chlamtac, Wireless and Mobile Network Architectures, Wiley Publication, 2nd edition, 2002.


Grading

There will be one midterm and one final exam

There may be projects. I did not determine them yet. Simulation or implementation projects No idea how hard they will be! No idea which language(s) they will be

implemented on! Attendance is important!



What is Wireless and Mobile Communication?


Wireless Communication

Transmitting voice and data using electromagnetic waves in open space

Electromagnetic waves Travel at speed of light (c = 3x108 m/s) Has a frequency (f) and wavelength ()

c = f x Higher frequency means higher energy photons The higher the energy photon the more penetrating is

the radiation


Electromagnetic Spectrum104 102 100 10-2 10-4 10-6 10-8 10-10 10-12 10-14 10-16

104 106 108 1010 1012 1014 1016 1018 1020 1022 1024

IR UV X-Rays Cosmic Rays

RadioSpectrum

1MHz ==100m100MHz ==1m 10GHz ==1cm

< 30 KHz VLF30-300KHz LF 300KHz – 3MHz MF3 MHz – 30MHz HF 30MHz – 300MHz VHF300 MHz – 3GHz UHF3-30GHz SHF> 30 GHz EHF

Microwave

Visible light


Wavelength of Some Technologies

GSM Phones: frequency ~= 900 Mhz wavelength ~= 33cm

PCS Phones frequency ~= 1.8 Ghz wavelength ~= 17.5 cm

Bluetooth: frequency ~= 2.4Gz wavelength ~= 12.5cm


Frequency Carries/Channels

The information from sender to receiver is carrier over a well defined frequency band. This is called a channel

Each channel has a fixed frequency bandwidth (in KHz) and Capacity (bit-rate)

Different frequency bands (channels) can be used to transmit information in parallel and independently.


Example

Assume a spectrum of 90KHz is allocated over a base frequency b for communication between stations A and B

Assume each channel occupies 30KHz. There are 3 channels Each channel is simplex (Transmission occurs in one way) For full duplex communication:

Use two different channels (front and reverse channels) Use time division in a channel

Channel 1 (b - b+30)

Channel 2 (b+30 - b+60)

Channel 3 (b+60 - b+90)

Station A Station B


Simplex Communication

Normally, on a channel, a station can transmit only in one way.

This is called simplex transmision To enable two-way communication (called

full-duplex communication) We can use Frequency Division Multiplexing We can use Time Division Multiplexing


Duplex Communication - FDD

FDD: Frequency Division Duplex

Base StationB

Mobile Terminal

M

Forward ChannelReverse Channel

Forward Channel and Reverse Channel use different frequency bands


Duplex Communication - TDD

TDD: Time Division Duplex

Base StationB

Mobile Terminal

M

A singe frequency channel is used. The channel is divided into time slots. Mobile station and base station transmits on the time slots alternately.

M B M B M B


Example - Frequency Spectrum Allocation in U.S. Cellular Radio Service

991 992 … 1023 1 2 … 799 991 992 … 1023 1 2 … 799

824-849 MHz 869-894 MHz

Reverse Channel Forward Channel

Channel Number Center Frequency (MHz)Reverse Channel 1 <=N <= 799 991 <= N <= 1023

Forward Channel 1 <=N <= 799 991 <= N <= 1023

0.030N + 825.00.030(N-1023) + 825.0

0.030N + 870.00.030(N-1023) + 870.0

(Channels 800-990 are unused)Channel bandwidth is 45 MHz


What is Mobility

Initially Internet and Telephone Networks is designed assuming the user terminals are static

No change of location during a call/connection A user terminals accesses the network always from a

fixed location Mobility and portability

Portability means changing point of attachment to the network offline

Mobility means changing point of attachment to the network online


Degrees of Mobility

Walking Users Low speed Small roaming area Usually uses high-bandwith/low-latency access

Vehicles High speeds Large roaming area Usually uses low-bandwidth/high-latency access Uses sophisticated terminal equipment (cell phones)


The Need for Wireless/Mobile Networking Demand for Ubiquitous Computing

Anywhere, anytime computing and communication You don’t have to go to the lab to check your email

Pushing the computers more into background Focus on the task and life, not on the computer Use computers seamlessly to help you and to make your

life more easier. Computers should be location aware

Adapt to the current location, discover services


More Examples

You walk into a Conference room or a shopping Mall with your PDA and your PDA is smart enough to collect and filter the public profiles of other people that are passing nearby

Of course other people should also have smart PDAs.

The cows in a village are equipped with GPS and GPRS devices and they are monitored from a central location on a digital map.

No need for a person to guide and feed them

You can find countless examples


How to realize Ubiquitous Computing

Small and different size computing and communication devices Tabs, pads, boards PDAs, Handhelds, Laptops, Cell-phones

A communication network to support this Anywhere, anytime access Seamless, wireless and mobile access Need for Personal Communication Services (PCS)

Ubiquitous Applications New software


Some Example Applications of Ubiquitous Computing

You walk into your office and your computer automatically authenticates you through your active badge and logs you into the Unix system

You go to a foreign building and your PDA automatically discovers the closest public printer where you can print your schedule and give to your friend

22

Introduction to Wireless networks Access computing/communication services, on the move

Wireless WANs– Cellular Networks: GSM, GPRS, CDMA– Satellite Networks: Iridium

Wireless LANs– WiFi Networks: 802.11– Personal Area Networks: Bluetooth

Wireless MANs– WiMaX Networks: 802.16– Mesh Networks: Multi-hop WiFi– Adhoc Networks: useful when infrastructure not available

Elective III - Code: 414463 A

Nitin S Ujgare


Nitin S Ujgare 23

Limitations of the mobile environment Limitations of the Wireless Network

limited communication bandwidth frequent disconnections heterogeneity of fragmented networks

Limitations Imposed by Mobility route breakages lack of mobility awareness by system/applications

Limitations of the Mobile Device short battery lifetime limited capacities

Mobile communication

Wireless vs. mobile Examples

stationary computer laptop in a hotel (portable) wireless LAN in historic buildings Personal Digital Assistant (PDA)

Integration of wireless into existing fixed networks:– Local area networks: IEEE 802.11, ETSI (HIPERLAN)– Wide area networks: Cellular 3G, IEEE 802.16– Internet: Mobile IP extension


Nitin S Ujgare 24


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384 Kbps

56 Kbps

54 Mbps

72 Mbps

5-11 Mbps

1-2 Mbps 802.11

Wireless Technology Landscape

Bluetooth

802.11b

802.11{a,b}Turbo .11a

Indoor

10 – 30m

IS-95, GSM, CDMA

WCDMA, CDMA2000

Outdoor

50 – 200m

Mid rangeoutdoor

200m – 4Km

Long rangeoutdoor

5Km – 20Km

Long distance com.

20m – 50Km

µwave p-to-p links

.11 p-to-p link

2G

3G


Reference model

Application

Transport

Network

Data Link

Physical

Medium

Data Link

Physical

Application

Transport

Network

Data Link

Physical

Data Link

Physical

Network Network

Radio


Perspectives Network designers: Concerned with cost-effective

design Need to ensure that network resources are efficiently utilized

and fairly allocated to different users.

Network users: Concerned with application services Need guarantees that each message sent will be delivered

without error within a certain amount of time.

Network providers: Concerned with system administration Need mechanisms for security, management, fault-tolerance

and accounting.


Wireless frequency allocation Radio frequencies range from 9KHz to 400GHZ (ITU)

Microwave frequency range 1 GHz to 40 GHz Directional beams possible Suitable for point-to-point transmission Used for satellite communications

Radio frequency range 30 MHz to 1 GHz Suitable for omnidirectional applications

Infrared frequency range Roughly, 3x1011 to 2x1014 Hz Useful in local point-to-point multipoint applications within confined

areas


Frequencies for mobile communication VHF-/UHF-ranges for mobile radio

simple, small antenna for cars deterministic propagation characteristics, reliable connections

SHF and higher for directed radio links, satellite communication small antenna, focusing large bandwidth available

Wireless LANs use frequencies in UHF to SHF spectrum some systems planned up to EHF limitations due to absorption by water and oxygen molecules

(resonance frequencies) weather dependent fading, signal loss caused by heavy

rainfall etc.


Wireless transmission

Wireless communication systems consist of: Transmitters Antennas: radiates electromagnetic energy into air Receivers

In some cases, transmitters and receivers are on same device, called transceivers.

Transmitter Receiver

AntennaAntenna


Transmitters Amplifier

Oscillator

Mixer Filter Amplifier

Antenna

Transmitter

Suppose you want to generate a signal that is sent at 900 MHz and the original source generates a signal at 300 MHz.

•Amplifier - strengthens the initial signal•Oscillator - creates a carrier wave of 600 MHz•Mixer - combines signal with oscillator and produces 900 MHz (also does modulation, etc)•Filter - selects correct frequency •Amplifier - Strengthens the signal before sending it

Source


Satellite Based Mobile Systems

Categorized as Two-way (or one-way) limited quality voice or data

transmission Very wide range and coverage

Large regions Sometimes global coverage Very useful in sparsely populated areas: rural areas, sea,

mountains, etc. Target: Vehicles and/or other stationary/mobile

uses Expensive base station (satellites) systems


History of Wireless and Mobile Communication


History

1831: Faraday had first started experimenting with electromagnetic waves. Electromagnetic wave:

one of the waves that are propagated by simultaneous periodic variations of electric and magnetic field intensity and that include radio waves infrared visible light ultraviolet, X rays Gamma rays


History – Mathematics and EM

1864: Maxwell who had been working on a mathematical model for electromagnetic waves finally published his paper on the subject. One of the consequences of his theories was that E.M.

waves would travel at near the speed of light. This had also been experimentally determined by others

at the time.


History – Existence of EM Waves

At the same time that Lodge was carrying out his experiments, Heinrich Hertz in Germany was also doing some of his own concerning Maxwell’s equations.

Hertz's investigations into Maxwell’s equations involved generation, detection, and measurement of waves in free space, rather than along wires.

1887: Hertz proves existence of EM waves; first spark transmitter generates a spark in a receiver several meters away

The units of frequency waves is named after him, 1 cycle/second equals a Hertz.


History – Frequency Tuning

In 1898: Tesla gave one of the first wireless demonstrations with a what we would call a remote control boat. He realized that things of this nature would need to only

respond to their own frequency, and remain inactive otherwise.

This was Tesla’s fundamental radio tuning invention, which he had first described several years earlier.


History – Transoceanic Communication

1901: Marconi successfully transmits radio signal across Atlantic Ocean from Cornwall to Newfoundland

1902: First bidirectional communication across Atlantic

1909: Marconi awarded Nobel prize for physics


History – Voice over Radio

1914: First voice over radio transmission 1930s: Mobile transmitters developed; radio

equipment occupied most of police car trunk 1935: Edwin Armstrong demonstrated frequency

modulation (FM) for the first time. Majority of police systems converted to FM


History – Mobile Telephony

1946: First public mobile telephone service was introduced. First interconnection of mobile users to public switched telephone network (PSTN)

1950-1960: AT&T Bell Labs developed theory and techniques for cellular telephony


History

1993: IS-95 code-division multiple-access (CDMA) spread- spectrum digital cellular system deployed in US

1993: CDPD (Cellular Digital Packet Data) over AMPS was realized

1994: GSM system deployed in US


History – Bluetooth, PCS

1994: Ericsson starts investigating a low-power, low-cost radio technology to remove cables around cell phones (born of Bluetooth idea)


History – 3G Trials and Progress

1998: The first call using a Nokia W-CDMA terminal in DoCoMo's trial network was completed at Nokia's R&D unit near Tokyo in Japan.

Jun 1998: CDMA2000 submitted to ITU for IMT-2000

Dec 1998: The first meetings of the 3GPP Technical Specification Groups in France.

1999: IEEE 802.11b approved (11 Mbps) 1999: The first open Bluetooth specification 1.0 is

released.


History – 3G Progress

2001 Ericsson and Vodafone UK claim to have made the world's first WCDMA voice call over commercial network.

Jun 2001: NTT DoCoMo launched a trial 3G service

June 2001: CDMA2000 1xEV-DO recognized as part of the 3G IMT-2000 standard

Elective III - Code: 414463 A Nitin S Ujgare 1.45

Mobile Devices

performanceperformance

Pager• receive only• tiny displays• simple text messages

Mobile phones• voice, data• simple text displays

PDA• simple graphical displays• character recognition• simplified WWW

Palmtop• tiny keyboard• simple versions of standard applications

Laptop• fully functional• standard applications

Sensors,embeddedcontrollers

References

Presentation by Shridhar Iyer on Wireless Communication, KR School of Information Technology, IIT Bombay.

Mobile and Wireless Networking İbrahim Korpeoğlu Computer Engineering Department Bilkent University, Ankara.

Yi-Bing Lin, Imrich Chlamtac, Wireless and Mobile Network Architectures, Wiley Publication, 2 nd edition, 2002

Wireless communication by Ranjan bose, NPTEL, HRD, IIT Delhi.


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