wireless communication-lect 1

8/7/2019 Wireless Communication-Lect 1

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Wireless Communication

Mobile and Ubiquitous Computing

Course Instructor: Dr. Zubair Shaikh

A Presentation on:

P resenter: Nom an Isla m


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Introduction

The communication does not require physical

cablesCan be classified into: Fixed Wireless Network Wireless Network with Fixed Access Points Ad hoc network


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A Cellular Network


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G enerations of Mobile Phones

1G AMPS , ETACS, JTACS, NMT

2G GSM, IS-95/CDMA One, GPRS, ED GE3G UMTS, CDMA 20004G WiMAX, UMB


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4G Vision


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4G of Mobile Communication

Fully Packet switched IP network

Convergence ServicesBroadband ServicesFlexibility and Personalized ServicesWorldwide roamingMobile Multimedia, Anytime Any where, G lobal MobilitySupport, Integrated Wireless Solution and CustomizedPersonal Services MA G ICSoftware Defined Radios

Ad hoc Networking


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Mobile A d hoc Networks

As defined by IETF:M A NET is an autonomous system of mobile routers(and associated hosts) connected by wireless links--the union of which form an arbitrary graph. The routersare free to move randomly and organize themselvesarbitrarily; thus, the network's wireless topology maychange rapidly and unpredictably. Such a network mayoperate in a standalone fashion, or may be connectedto the larger Internet


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US Future Combat System Ubiquitous Computing

Disaster Recovery Automotive networks

A d hoc networks are expected to become part of future 4G -architecture

Mobile Workers

Sensor Networks

A pplications of M A NET


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A coustic Modems for UbiquitousComputing

Sound waves are characterized by:

Comparatively Low data rate Sound waves can be localized within rooms No LOS Can be exposed to Humans

Digital Voices project explores device communicationusing soundIt analyzed common modulation techniques and thesounds they produce


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A pplications of A ccoustic Modems

Can easily be deployed in the existing voiceinfrastructureBenefits from human awareness of the communicationRequires short-range broadcasts enclosed within wallsand windowsSteganography Agencies conducting secret operations might be interested insuch an application, given that these sounds can be broadcast

by traditional media and can be picked up anywhere in theworld with a laptop or PDA.

Entertainment


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D igital Voices project

Straightforward application of standard modulationtechniques used in non-audible modems isinappropriate for audible modemsExperiments show that constructing aerial acousticmodems in software and using the existing hardwareinfrastructure for sound is feasible

In fact, modems produce sounds that are relativelypleasing to humans over short time periodsIn most of cases, it was impossible to discriminatesynthesized sound with a natural sound


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B luetooth Radio System

A low-cost, low-power radio-based cable replacement

Enabled electronic devices to communicate wirelesslyvia short-range ad hoc radio connectionsThe technology enables the design of low-power,small-sized, low-cost radios that can be embedded inexisting (portable) devices. Eventually, these

embedded radios will lead toward ubiquitousconnectivity and truly connect everything to everythingBluetooth system is the first commercial ad hoc radiosystem envisioned to be used on a large scale andwidely available to the public


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Issues

Radio Spectrum ISM Band (2.45 GHz)Interference Immunity Microwave Ovens and lighting waves also use same band Interference suppression can be done by DSSMultiple Access Schemes FH-CDMA Set of 79 hop carriers are usedModulation scheme Gaussian shaped Frequency Shift Keying


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Issues contd

Medium Access Control An FH Bluetooth channel is associated with a piconet In a piconet, there is one master node and rest are slaves Master controls the access controlPower Management (different modes: park, idle, sniff mode etc.)

Security Authentication using challenge response mechanismInter-piconet communication scatternet


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B luetooth A uthenticationMechanism


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Ir DA

Characterized by: Marginal cost to add infrared to a product , under $5 Data rates of up to 11 5 kb/s Range from contact (0 m) through at least 1 m Angular coverage defined by a 1530 degree half-angle cone

A suite of protocols for infrared (IR) exchange of data

between two devices, up to1

or 2 meters apart (20 to30 cm for low-power devices)


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Ir DA

It is present in virtually all new PDAs, emerging

in mobile phones, pagers, digital cameras, andimage capture devicesProvides a communications platform andapplication services fit for the era of informationappliances and which excel in the area of easeof useCan be used for point-to-multipointcommunication


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References

[1] Wireless Communications, Principles and Practices , TheodoreS. Rappaport, 2 nd Edition

[2] http://www.ietf.org[3] The Bluetooth Radio System , Jaap C. Haartsen, Ericsson Radio

Systems B.V., IEEE Personal Communications February 2000[4] Acoustic Modems for Ubiquitous Computing , Cristina Videira

Lopes University of California, Irvine Pedro M.Q. Aguiar, TechnicalUniversity of Lisbon, IEEE CS and IEEE ComSoc, 1536-1268/03/$ 17.00 2003 IEEE

[5] IrDA: Past, Present and Future , Stuart Williams, HPLaboratories, IEEE Personal Communications, February 2000


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Steganography

Conceal the message and hope that others

cant find it (Steganography)Invisible InksMicrodotsDNA based SteganographyWatermarking

wireless communication-lect 1

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