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CSc 82020 Wireless Networking and Mobile Computing

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Title: CSc 82020 Wireless Networking and Mobile Computing


1
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

2
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

3
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 212-237-8826
  • Class WWW site http//jjcweb.jjay.cuny.edu/ssengu
    pta/
  • Blackboard online

4
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.

5
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

6
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

7
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

8
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.

9
Questions??
10
Lecture 1Wireless Introduction
11
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

12
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

14
WLAN Market WiFi
  • WLAN growing exponentially
  • Today, NY city is totally covered by Wi-Fi
    hotspots

Source AirTight Networks
15
Today, Variety of Wireless-Capable Devices
But how did it all get started?
Image courtesy Google
16
An overview of Wireless Networks
17
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
18
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
19
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

20
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?

21
Circuit Switching
  • End-end resources reserved for call
  • dedicated bandwidth resources no sharing
  • circuit-like (guaranteed) performance
  • call setup required

22
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

23
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

24
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
25
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

26
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
27
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

28
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
29
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
30
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

31
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

32
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
33
  • Wireless Sensor Networks
  • Particularly useful for sensing and Event
    detection
  • Battlefield surveillance
  • Security surveillance
  • Sensor Nodes
  • Low power, Small size

Image courtesy Google
34
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
35
Wireless Technical Challenges Basic Concepts
36
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

37
Challenge 2 Open Wireless Medium
  • Wireless interference

S1
R1
S2
R1
38
Challenge 2 Open Wireless Medium
  • Wireless interference
  • Hidden terminals

S1
R1
S2
R1
S1
R1
S2
39
Challenge 2 Open Wireless Medium
  • Wireless interference
  • Hidden terminals
  • Exposed terminal

S1
R1
S2
R1
S1
R1
S2
R1
S1
S2
R2
40
Challenge 2 Open Wireless Medium
  • Wireless security
  • eavesdropping
  • jamming
  • denial of service
  • and many more

41
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

42
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.

43
Challenge 5 Crowded Spectrum FCC Chart
http//www.ntia.doc.gov/osmhome/allochrt.pdf
44
  • 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
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