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Prof. Shamik Sengupta Office 4210 N [email protected] http://jjcweb.jjay.cuny.edu/ssengupta/ Fall 2010. CSc 82020 Wireless Networking and Mobile Computing. What is the course about?. Wireless networking and mobile computing In-depth coverage of the wireless technologies - PowerPoint PPT Presentation
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CSc 82020 CSc 82020 Wireless Networking and Mobile ComputingWireless Networking and Mobile Computing
Prof. Shamik Sengupta
Office 4210 N
http://jjcweb.jjay.cuny.edu/ssengupta/
Fall 2010
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…
Timing and Contact Information
Class meeting time: Tuesday (6:30pm – 8:30pm)
Office hours and location:– John Jay College Campus (Columbus Circle), North Hall Building, 4210N
– Tuesday, 4pm – 5 pm
– To be decided @ GC– Tuesday, 5pm – 6 pm
Email: [email protected] Office Phone: 212-237-8826 Class WWW site: http://jjcweb.jjay.cuny.edu/ssengupta/ Blackboard online
Course Material Information
No single textbook Class notes and slides References to current materials from journals, magazines and other
websites Few Reference Texts:
1. Wireless Networks by P. Nicopolitidis, M. S. Obaidat, G. I. Papadimitriou, A. S. Pomportsis. Publisher: Wiley. ISBN-10: 0470845295. ISBN-13: 978-0470845295.
2. Wireless Communications: Principles and Practice by Theodore S. Rappaport. Publisher: Prentice Hall; 2nd edition. ISBN-10: 0130422320. ISBN-13: 978-0130422323.
3. Wireless Communications & Networking by Vijay Garg. Publisher: Morgan Kaufmann; 1st edition. ISBN-10: 0123735807. ISBN-13: 978-0123735805.
4. Wireless Communications & Networks, 2nd edition by William Stallings. ISBN-10: 0131918354. ISBN-13: 9780131918351.
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
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
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
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.
Questions…??Questions…??
Lecture 1Lecture 1Wireless IntroductionWireless Introduction
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 decade…with more to come Wireless is no longer a luxury but a necessity
Wireless Technology is everywhere
Driven by technology and visionWireless technologiesDevice miniaturizationMobile computing platforms
Need for ubiquitous connectivityThe field is moving fast
Image courtesy: Google
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
Estimated Global Subscribers mid 2006
1023
2200
250
0
500
1000
1500
2000
2500
Internet Cell Phones Broadband
[su
bs
x000
,000
]
WLAN Market: WiFi
0
1
2
3
4
5
$-b
il
2001 2002 2003 2004 2005
Forecast Sales of Wi-Fi Equipment(Source: InfoTech Trends)
Source: Pyramid Research
Worldwide WLAN Infrastructure Shipments (Source: Gartner)
0
1
2
3
4
5
6
7
Mil
lio
ns o
f U
nit
s
Source: AirTight Networks
WLAN growing exponentiallyToday, NY city is totally covered by Wi-Fi hotspots
Today, Variety of Wireless-Capable Devices
But how did it all get started?
Image courtesy: Google
An overview of Wireless NetworksAn overview of Wireless Networks
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
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
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
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? ***
Circuit Switching
End-end resources reserved for “call”
– dedicated bandwidth resources: no sharing
– circuit-like (guaranteed) performance
– call setup required
Packet Switching
A
B
C
1.5 Mb/s
D E
queue of packetswaiting 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
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 FCC’s 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
IEEE Wireless Standards
IEEE 802.15 Bluetooth
WAN
MAN
LAN
PAN
IEEE 802.11
Wi-Fi
IEEE 802.16d WiMAX
IEEE 802.20
IEEE 802.16e
RANIEEE 802.22
Image courtesy: Google
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
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
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
WiMAX: worldwide interoperability of microwave access
802.16-2004
802.16-2004
Rural
Rural
Rural
Urban
DSL/T1 Replacemen
t802.16-2004802.16-2004
WiFiWiFi
WiFiWiFi
Rural
Broadband
802.16-2004802.16-2004
WiFiWiFi
WiFiWiFi
WiFiWiFi
WiFiWiFi
WiFiWiFi
802.16e
802.16e
Image courtesy: Google
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
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
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
Ad-Hoc/Mesh Networks
Wireless Ad hoc networks1. Mobile ad hoc networks
2. Wireless mesh networks
3. Wireless sensor networks
Image courtesy: Google
Mobile ad hoc network
Wireless mesh network
Wireless Sensor Networks
• Particularly useful for sensing and Event detection• Battlefield surveillance• Security surveillance
• Sensor Nodes• Low power, Small size
Image courtesy: Google
Wireless Sensor Network Classification
Infrastructure-less•No human intervention• Not replaceable• One time deployment• Finite energy available with sensor nodes
Infrastructured•In buildings• Secured places
Image courtesy: Google
Wireless Technical Challenges & Basic Concepts
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
Challenge 2: “Open” Wireless Medium
Wireless interference
S1
S2
R1
R1
Wireless interference
Hidden terminals
Challenge 2: “Open” Wireless Medium
S1
S2
R1
R1
S1 R1 S2
Challenge 2: “Open” Wireless Medium
Wireless interference
Hidden terminals
Exposed terminal
S1
S2
R1
R1
S1 R1 S2
R1 S1 S2 R2
Challenge 2: Open Wireless Medium
Wireless security– eavesdropping
– jamming
– denial of service
– and many more…
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
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.
Challenge 5: Crowded Spectrum: FCC Chart
http://www.ntia.doc.gov/osmhome/allochrt.pdf
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