CSc 82020 Wireless Networking and Mobile Computing

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CSc 82020 Wireless Networking and Mobile
Computing

• Prof. Shamik Sengupta
• Office 4210 N
• ssengupta_at_jjay.cuny.edu
• http//jjcweb.jjay.cuny.edu/ssengupta/
• Fall 2010

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What is the course about?

• Wireless networking and mobile computing
• In-depth coverage of the wireless technologies
• Understanding the tradeoffs and limitations of
  different wireless networking architectures and
  protocols
• Improving your skills of analyzing/solving
  wireless network design problems
• Theoretical knowledge development as well as
  hands on experience and prototype development
• Goals
• Learning applications, concepts, practice
• Enjoy

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Timing and Contact Information

• Class meeting time Tuesday (630pm 830pm)
• Office hours and location
• John Jay College Campus (Columbus Circle), North
  Hall Building, 4210N
• Tuesday, 4pm 5 pm
• To be decided _at_ GC
• Tuesday, 5pm 6 pm
• Email ssengupta_at_jjay.cuny.edu
• Office Phone [phone]
• Class WWW site http//jjcweb.jjay.cuny.edu/ssengu
  pta/
• Blackboard online

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Course Material Information

• No single textbook
• Class notes and slides
• References to current materials from journals,
  magazines and other websites
• Few Reference Texts
• Wireless Networks by P. Nicopolitidis, M. S.
  Obaidat, G. I. Papadimitriou, A. S. Pomportsis.
  Publisher Wiley. ISBN-10 0470845295. ISBN-13
  978-0470845295.
• Wireless Communications Principles and Practice
  by Theodore S. Rappaport. Publisher Prentice
  Hall 2nd edition. ISBN-10 0130422320. ISBN-13
  978-0130422323.
• Wireless Communications Networking by Vijay
  Garg. Publisher Morgan Kaufmann 1st edition.
  ISBN-10 0123735807. ISBN-13 978-0123735805.
• Wireless Communications Networks, 2nd edition
  by William Stallings. ISBN-10 0131918354.
  ISBN-13 9780131918351.

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Course Material Information (contd.)

• Other References
• ACM digital library - http//portal.acm.org/dl.cfm
  
• IEEE Xplore - http//ieeexplore.ieee.org/
• Reading list in the class website
• Will be updated continuously

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Course Syllabus Overview

• Wireless Introduction
• Wireless Communication
• The Cellular concept
• Wi-Fi (IEEE 802.11)
• Wimax (IEEE 802.16)
• Wireless personal area network (WPAN)
• Ad hoc, sensor, mesh networking
• Single channel and multi-channel networks
• Dynamic Spectrum Access (DSA) and Cognitive Radio
  (CR)
• Economics of wireless spectrum
• Mobile IP, Mobility management
• Wireless security and vulnerabilities

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Grading Information

• Workload and grading

Course work approx
Project Presentation 40
Homework assignments 30
Midterm exam 30

• No final exam
• Extra-credit assignments as decided by Instructor
• Late policy
• Submission will not be accepted after due date
• Permission needed for exceptional circumstances
• Attendance needed

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Project Presentation

• Project (Approx. 15 weeks time)
• The term project is a original research project
  related to any topic in wireless
• A 1-page initial proposal is due by 9/21/2010
• Individual Project or 2-person team project
• Collaborated project is expected to show synergy
• The project paper is due at the end of the
  semester
• Presentation (approx. 20 min.)
• Decide your topic as soon as possible and discuss
  with me. Start as early as possible.

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Questions??
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Lecture 1Wireless Introduction
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Why Wireless?

• Advantages
• Mobility (on the go)
• Flexibility (any place, any time, temporary,
  permanent)
• No problems with wiring (e.g. historical
  buildings, fire protection, esthetics), also cost
  reducing
• Robust against disasters like earthquake, fire
  in emergency situations
• It has really been a wireless revolution
  decadewith more to come
• Wireless is no longer a luxury but a necessity

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Wireless Technology is everywhere

• Driven by technology and vision
• Wireless technologies
• Device miniaturization
• Mobile computing platforms
• Need for ubiquitous connectivity
• The field is moving fast

Image courtesy Google
13
The Wireless Revolution

• Cellular is the fastest growing sector of
  communication industry (exponential growth since
  1982, with over 2.5 billion users worldwide
  today)
• Wireless mobile services grew from 11 million
  subscribers worldwide in 1990 to over 2 billion
  in 2005
• In the same period, the Internet grew from being
  a curious academic tool to about 1 billion users

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WLAN Market WiFi

• WLAN growing exponentially
• Today, NY city is totally covered by Wi-Fi
  hotspots

Source AirTight Networks
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Today, Variety of Wireless-Capable Devices
But how did it all get started?
Image courtesy Google
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An overview of Wireless Networks
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Wireless History

• 1895 Marconi demonstrated the first radio based
  wireless transmission
• 1901 First radio reception across the Atlantic
  Ocean
• 1924 First Mobile Radio Telephone

Image courtesy Google
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Early Cellular Systems

• 1940s-50s cellular concept discovered
• 1946 First Mobile Telephone System (MTS)
  introduced in 25 cities in USA
• Half-duplex
• Everything was manual in MTS
• Maximum 3 calls supported!!!
• Huge Mobile transceivers
• 1960 Improved MTS (IMTS)
• Automatic call switching and full duplex
• Supported 23 channels
• MTS IMTS used high power BS and used the
  spectrum inefficiently

Image courtesy Google
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Early Cellular Systems (contd.)

• Post-1960 High power BS replaced by low-power
  low coverage stations
• 1st Generation (1G) Analog Systems
• Designed in late 1960s but due to regulatory
  delays deployed in early 1980s
• 1983 The first analog cellular system deployed
  in Chicago Advanced Mobile Phone System (AMPS),
  saturated by 1984
• 2nd generation (2G) Digital Systems early 90s
• Represent voice signal digitally
• Higher capacity
• Higher speed
• Reduced cost and power efficiency of digital
  hardware
• Encryption

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Early Cellular Systems (contd.)

• A number of 2G systems became very popular
• Global System for Mobile Communications (GSM)
  became famous in Europe and partly in USA
• Operating around 900 MHz and also in 1800 MHz
• Primarily for voice
• GSM defines number of frequency channels, divided
  into uplink and downlink, in turn divided into
  timeslots
• We will study GSM in detail later in this class
• High Speed Circuit Switched Data (HSCSD) and
  General Packet Radio Service (GPRS)
• Extension of GSM Primarily for data applications
• GPRS is packet switched while GSM and HSCSD are
  circuit switched network
• What is circuit switching and packet
  switching?

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Circuit Switching

• End-end resources reserved for call
• dedicated bandwidth resources no sharing
• circuit-like (guaranteed) performance
• call setup required

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Packet Switching
C
A
1.5 Mb/s
B
queue of packets waiting for output link

• each end-end data stream divided into packets
• user A, B packets share network resources
• each packet uses full link bandwidth
• resources used as needed

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Wireless Data Systems

• Characteristics of data systems are different
  from voice systems
• Data systems are characterized by bursty
  transmissions
• Unless there is a packet to transmit, terminals
  remain idle
• Appropriate for packet switching and sharing the
  resources among multiple users
• ALOHANET developed at University of Hawaii,
  first wireless data systems, 1971
• Wireless data systems revolutionized by Wireless
  LAN
• Commenced in the late 1980s
• Driven by FCCs decision to authorize
  license-free bands
• Provide high speed data within a relatively small
  region
• IEEE standard 802.11
• Will study IEEE 802.11 system in detail
• A wide variety of wireless data systems now exist
  can be categorized based on coverage area

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IEEE Wireless Standards
RAN
IEEE 802.22
WAN
IEEE 802.20 IEEE 802.16e
MAN
IEEE 802.16d WiMAX
LAN
IEEE 802.11 Wi-Fi
PAN
IEEE 802.15 Bluetooth
Image courtesy Google
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Wireless LANs WiFi/802.11

• Based on the IEEE 802.11a/b/g/n family of
  standards
• Designed to provide in-building or campus
  broadband coverage.
• IEEE 802.11b peak physical layer data rate of 11
  Mbps
• IEEE 802.11a/g peak physical layer data rate of
  54 Mbps and indoor coverage over a distance of
  100 feet.
• Much higher peak data rates than 3G systems,
  primarily since it operates over a larger
  bandwidth (20 MHz).
• Its MAC scheme CSMA (Carrier Sense Multiple
  Access) is inefficient for large numbers of users
• The interference constraints of operating in the
  license-exempt band is likely to significantly
  reduce the actual capacity of outdoor Wi-Fi
  systems.
• Wi-Fi systems are not designed to support
  high-speed mobility

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WPAN (Wireless Personal Area Network)

• Cable replacement RF technology (low cost)
• Short range 10m (1mW), 100m (100 mW)
• Lower power than WiFi
• Widely supported by telecommunications, PC, and
  consumer electronics companies.
• Hands free phone (ear set) for cars, internet
  chat/VoIP
• Intra-car networking announced by some car
  manufacturers in Europe
• IEEE 802.15 includes seven task groups
• Numbered from 1 7 with each of them having own
  responsibility

Image courtesy Google
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WPAN (Wireless Personal Area Network)

• IEEE 802.15.1
• WPAN/Bluetooth standard includes MAC and PHY
  spec.
• IEEE 802.15.2
• Addresses the issue of coexistence of WPAN with
  other wireless devices such as WLAN
• IEEE 802.15.3
• MAC and PHY standard for high rate WPANs
• IEEE 802.15.4
• MAC and PHY standard for low rate but high
  endurance (power-aware)
• IEEE 802.15.5
• Mesh networking standards for WPAN devices
• IEEE 802.15.6
• Body area network standard (low power, low
  frequency), can be helpful in health monitoring
• IEEE 802.15.7
• Very recently started..still working
• PHY and MAC standard for visible light
  communications

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WiMAX worldwide interoperability of microwave
access
802.16-2004
WiFi
WiFi
WiFi
Urban DSL/T1 Replacement
WiFi
WiFi
802.16-2004
WiFi
802.16-2004
WiFi
Rural
Rural
Rural Broadband
Rural
Image courtesy Google
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WiMAX Fixed and Mobile

• WiMAX Fixed / Nomadic
• 802.16d or 802.16-2004
• Usage Backhaul, Wireless DSL
• Devices outdoor and indoor installed CPE
• Frequencies 2.5GHz, 3.5GHz and 5.8GHz (Licensed
  and LE)
• Description wireless connections to homes,
  businesses, and other WiMAX or cellular network
  towers

• WiMAX Mobile
• 802.16e
• Usage Long-distance mobile wireless broadband
• Devices PC Cards, Notebooks and future handsets
• Frequencies 2.5GHz
• Description Wireless connections to laptops,
  PDAs and handsets when outside of Wi-Fi hotspot
  coverage

Image courtesy Google
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Wide Area Satellite Systems

• Cover very large areas
• Different orbit heights
• Low Earth Orbit (LEO) 1000 miles
• Mid Earth Orbit (MEO) 6000 miles
• Geosynchronous Orbit (GEO) 22,300 miles
• Optimized for one-way transmission
• location positioning, GPS systems, Satellite
  Radio
• Most two-way systems struggling or bankrupt

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Ad hoc Networks

• All the wireless networks mentioned so far are
  known as infrastructure network
• Require initial setup
• Radios mostly follow master/slave concept
• Base stations act as master while user devices
  are controlled by BS
• Infrastructure networks are not appropriate in
• emergency situations like natural disasters or
• military conflicts or
• in areas where access is difficult
• Ad hoc networks are particularly suitable in such
  scenarios
• Decentralized
• Peer-to-peer
• Does not depend on a central entity
• Minimal configuration and quick deployment

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Ad-Hoc/Mesh Networks

• Wireless Ad hoc networks
• Mobile ad hoc networks
• Wireless mesh networks
• Wireless sensor networks

Wireless mesh network
Mobile ad hoc network
Image courtesy Google
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• Wireless Sensor Networks

• Particularly useful for sensing and Event
  detection
• Battlefield surveillance
• Security surveillance
• Sensor Nodes
• Low power, Small size

Image courtesy Google
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Wireless Sensor Network Classification

• Infrastructured
• In buildings
• Secured places

• Infrastructure-less
• No human intervention
• Not replaceable
• One time deployment
• Finite energy available with sensor nodes

Image courtesy Google
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Wireless Technical Challenges Basic Concepts
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Challenge 1 Unreliable and Unpredictable
Wireless Coverage

• Wireless channel feels very different from a
  wired channel.
• Wireless links are not reliable they may vary
  over time and space
• Noise adds on to the signal
• Signal strength falls off rapidly with distance
• Signal strength may weaken due to obstacles
• Medium air shared among many users
• Results
• Capacity is shared with others
• Variable capacity
• Unreliable channel errors, outages
• Variable delays

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Challenge 2 Open Wireless Medium

• Wireless interference

S1
R1
S2
R1
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Challenge 2 Open Wireless Medium

• Wireless interference
• Hidden terminals

S1
R1
S2
R1
S1
R1
S2
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Challenge 2 Open Wireless Medium

• Wireless interference
• Hidden terminals
• Exposed terminal

S1
R1
S2
R1
S1
R1
S2
R1
S1
S2
R2
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Challenge 2 Open Wireless Medium

• Wireless security
• eavesdropping
• jamming
• denial of service
• and many more

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Challenge 3 Mobility

• Mobility causes poor-quality wireless links
• Mobility causes intermittent connection
• under intermittent connected networks,
  traditional routing, TCP, applications all break
• Mobility changes context, e.g., location

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Challenge 4 Portability Energy-Constrained Nodes

• Limited battery power
• Limited processing, display and storage
• Each node can only send a finite number of bits.
• Transmit energy minimized by maximizing bit time
• Introduces a delay versus energy tradeoff for
  each bit
• Short-range networks must consider transmit and
  processing energy
• Sophisticated techniques not necessarily
  energy-efficient
• Sleep modes save energy but complicate networking
• Changes everything about the network design
• Delay vs. throughput vs. node/network lifetime
  tradeoffs.
• Optimization of node cooperation.

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Challenge 5 Crowded Spectrum FCC Chart
http//www.ntia.doc.gov/osmhome/allochrt.pdf
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• The field is challenging
• With new wireless technologies and with more
  sophistication, there are additional challenges
• Operational
• Security
• Efficiency and more
• This course is all about
• learning current and new wireless technologies
• Understanding the challenges
• Design Implement new mechanisms to counteract
  against the challenges and make wireless
  networking more efficient