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Mobile Computing and Wireless Communications
CSE 40814/60814 Fall 2008
Course Overview Instructor: Christian Poellabauer
354 Fitzpatrick Hall [email protected] 574-631-9131 Office hours: Tuesday 1-2pm, Wednesday 9-10am, and
by appointment Teaching Assistant: Jun Yi
214 Cushing Hall [email protected] Office hours: Tuesday and Wednesday 4-5pm and by
appointment
Course Overview Course web site:
www.cse.nd.edu/~cpoellab/cse40814/
Course material: no textbook, slides and other material will be provided suggested reading available on web site announcements and assignments on web site and in
class
Course grading: homework assignments (30%) projects (40%) exams (30%)
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Projects Teams of 1-2 students (2 student teams will be
expected to deliver “more” than individual students) Projects build on each other! Short deadlines (1-2 weeks)!
Equipment Rules You have access to the DARTS Lab (356B Fitzpatrick) Generally, devices are to remain in the room
Exceptions: you can carry the smartphone with you you can take out equipment with permission by the instructor
(contact me if you need to do so)
Never keep the door open, never give the door code to anybody else, never take stuff out, keep the room clean and organized, share equipment, etc.
The room has about 200k worth of equipment, again: treat it nicely and don’t make it too easy for thieves
Projects Set-up WiFi (ad-hoc, managed modes), BT, Zigbee Socket communication via a base station Voice (video) communications between two devices Communications using base stations and ad-hoc Multi-hop communications Multi-receiver communications Location-awareness and tracking Routing (e.g., using GPS) Context-aware applications, network protocols,
resource management, …
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Mobile Computing versus Wireless Communication
Applications Location-awareness Mobility Support Security Resource Management Network Protocols Broadcast Technologies Standards Wireless Medium
Wireless Communication
Mobile Computing
Overview Introduction Wireless Transmission MAC Layer Telecommunications Systems Satellite Communication Broadcast Systems WLAN Mobile Network Layer Mobile Transport Layer Mobility Support Location Management Wireless Sensor Networks Resource Management Wireless Network Security Outlook and Summary
Questions?
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Future Computing
Computers are integrated small, cheap, portable, replaceable - no more separate devices
Technology is in the background computer are aware of their environment and adapt (“location awareness”) computer recognize the location of the user and react appropriately (e.g.,
call forwarding, fax forwarding, “context awareness”)
Advances in technology more computing power in smaller devices flat, lightweight displays with low power consumption new user interfaces due to small dimensions new device features (GPS, accelerometer, camera, …) multiple wireless interfaces: wireless LANs, wireless WANs, Bluetooth,
Zigbee, cellular networks, etc.
Mobile Communications Two aspects of mobility:
user mobility: users communicate (wirelessly) “anytime, anywhere, with anyone”
device portability: devices can be connected anytime, anywhere to the network
Wireless vs. mobile Examples stationary computer notebook in a hotel wireless LANs in historic buildings Personal Digital Assistant (PDA)
The demand for mobile communication creates the need for integration of wireless networks into existing fixed networks: local area networks: standardization of IEEE 802.11 Internet: Mobile IP extension of the internet protocol IP wide area networks: e.g., internetworking of GSM and ISDN, VoIP over
WLAN and POTS
Applications Vehicles
transmission of news, road condition, weather, music (e.g., via DAB/DVB-T in Europe)
personal communication using GSM/UMTS position via GPS local ad-hoc network with vehicles close-by to prevent accidents,
guidance system, redundancy vehicle data (e.g., from busses, high-speed trains) can be
transmitted in advance for maintenance
Emergencies early transmission of patient data to the hospital, current status,
first diagnosis replacement of a fixed infrastructure in case of earthquakes,
hurricanes, fire etc. crisis, war, ...
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On the Road...
ad h
oc UMTS, WLAN,
DAB, DVB, GSM, cdma2000, TETRA, ...
Personal Travel Assistant, PDA, Laptop, GSM, UMTS, WLAN, Bluetooth, ...
A Business Man’s Morning
UMTS 2 Mbit/s
UMTS, GSM 384 kbit/s
LAN 100 Mbit/s, WLAN 54 Mbit/s
UMTS, GSM 115 kbit/s
GSM 115 kbit/s, WLAN 11 Mbit/s
GSM/GPRS 53 kbit/s Bluetooth 500 kbit/s
GSM/EDGE 384 kbit/s, DSL/WLAN 3 Mbit/s
DSL/WLAN 3 Mbit/s
Replacement of Fixed Networks Remote sensors, e.g., weather, earth activities Flexibility for trade shows LANs in historic buildings
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Entertainment, Education Ad-hoc networks for multi user games Intelligent travel guide with up-to-date
location dependent information Mobile Multimedia (videos, TV, …)
Location-dependent Services Location aware services
what services, e.g., printer, fax, phone, server, etc. exist in the local environment
Follow-on services automatic call-forwarding, transmission of the actual workspace
to the current location Information services
“push”: e.g., current special offers in the supermarket “pull”: e.g., where can I find the closest Starbucks?
Support services caches, intermediate results, state information, etc. “follow” the
mobile device through the fixed network
Privacy who should gain knowledge about the location?
Mobile Devices
Pager • receive only • tiny displays • simple text messages
Mobile phones • voice, data • simple graphical displays
PDA • graphical displays • character recognition • simplified WWW
Smartphone • tiny keyboard • simple versions of standard applications
Laptop/Notebook • fully functional • standard applications
Sensors, embedded controllers
www.scatterweb.net
No clear separation between device types possible (e.g., smart phones, embedded PCs, …)
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Device Portability: Challenges Power consumption
limited computing power, low quality displays, small disks due to limited battery capacity
CPU: power consumption ~ V2f V: supply voltage, can be reduced to a certain limit f: clock frequency, can be reduced temporally
Loss of data higher probability, has to be included in advance into the design (e.g.,
defects, theft) Limited user interfaces
compromise between size of fingers and portability integration of character/voice recognition, abstract symbols
Limited memory limited usage of mass memories with moving parts flash-memory as alternative
Wireless vs. Fixed Networks Higher loss-rates due to interference
emissions of, e.g., engines, lightning Restrictive regulations of frequencies
frequencies have to be coordinated, useful frequencies are almost all occupied
Low transmission rates tens of kbit/s to some Mbit/s
Higher delays, higher jitter connection setup time with GSM in the second range, several hundred
milliseconds for other wireless systems Lower security, simpler active attacking
radio interface accessible for everyone, base station can be simulated, thus attracting calls from mobile phones
Always shared medium secure access mechanisms important
Data Rates
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History of Wireless Networks Many people in history used light for communication
heliographs, flags (“semaphore”), ... 150 BC smoke signals for communication;
(Polybius, Greece) 1794, optical telegraph, Claude Chappe
Electromagnetic waves: 1831 Faraday demonstrates
electromagnetic induction J. Maxwell (1831-79): theory of electromagnetic fields, wave
equations (1864) H. Hertz (1857-94): demonstrates
with an experiment the wave character of electrical transmission through space (1888, in Karlsruhe, Germany)
History of Wireless Networks 1896 Guglielmo Marconi
first demonstration of wireless telegraphy
long wave transmission, high transmission power necessary (> 200kW)
1907 Commercial transatlantic connections huge base stations
(30 100m high antennas) 1915 Wireless voice transmission New York - San Francisco 1920 Discovery of short waves by Marconi
reflection at the ionosphere smaller sender and receiver, possible due to the invention of the vacuum
tube (1906, Lee DeForest and Robert von Lieben)
History of Wireless Networks 1928 Numerous TV broadcast trials (across Atlantic, color TV, news) 1933 Frequency modulation (E. H. Armstrong) 1982 Start of GSM-specification
goal: pan-European digital mobile phone system with roaming 1983 Start of the American AMPS (Advanced Mobile Phone System,
analog) 1992 Start of GSM
automatic location, hand-over, cellular services: data with 9.6kbit/s, FAX, voice, ...
1996 HiperLAN (High Performance Radio Local Area Network) 1997 Wireless LAN - IEEE802.11
IEEE standard, 2.4 - 2.5GHz and infrared, 2Mbit/s already many (proprietary) products available in the beginning
1998 Specification of GSM successors UMTS (Universal Mobile Telecommunications System): IMT-2000 Iridium
66 satellites (+6 spare), 1.6GHz to the mobile phone
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History of Wireless Networks 1999 Standardization of additional wireless LANs
IEEE standard 802.11b, 2.4-2.5GHz, 11Mbit/s Bluetooth for piconets, 2.4GHz, <1Mbit/s Decision about IMT-2000
several “members” of a “family”: UMTS, cdma2000, DECT, … Start of WAP (Wireless Application Protocol) and i-mode
first step towards a unified Internet/mobile communication system access to many services via the mobile phone
2000 GSM with higher data rates HSCSD offers up to 57,6kbit/s first GPRS trials with up to 50 kbit/s (packet oriented!) UMTS auctions
hype followed by disillusionment (100 billion Euros paid in Europe for licenses) Iridium goes bankrupt
2001 Start of 3G systems Cdma2000 in Korea, UMTS tests in Europe, Foma (almost UMTS) in Japan
History of Wireless Networks 2002
WLAN hot-spots start to spread 2005
WiMax starts as DSL alternative first ZigBee products
2006 WLAN draft for 250 Mbit/s (802.11n) using MIMO WPA2 mandatory for Wi-Fi WLAN devices
2007 over 3.3 billion subscribers for mobile phones
2008 “real” Internet widely available on mobile phones (standard browsers, decent data rates)
Overview of Developments
cellular phones satellites wireless LAN
cordless phones
1992: GSM
1994: DCS 1800
2001: IMT-2000
1987: CT1+
1982: Inmarsat
-A
1992: Inmarsat-B Inmarsat-M
1998: Iridium
1989: CT 2
1991: DECT 199x:
proprietary
1997: IEEE 802.11
1999: 802.11b, Bluetooth
1988: Inmarsat
-C
analog
digital
1991: D-AMPS
1991: CDMA
1981: NMT 450
1986: NMT 900
1980: CT0
1984: CT1
1983: AMPS
1993: PDC
4G – fourth generation: when and how?
2000: GPRS
2000: IEEE 802.11a
200?: Fourth Generation (Internet based)
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Worldwide subscribers cellular
Note that the curve starts to flatten in 2000 – 2007: over 3.3 billion subscribers
Cellular Subscribers Region (June 2002)
Reference Model Used in Class
Application
Transport
Network
Data Link
Physical
Medium
Data Link
Physical
Application
Transport
Network
Data Link
Physical
Data Link
Physical
Network Network
Radio
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Influence of Mobile Communication to Layer Model
Application layer
Transport layer
Network layer
Data link layer
Physical layer
service location new/adaptive applications multimedia congestion/flow control quality of service addressing, routing device location hand-over authentication media access/control multiplexing encryption modulation interference attenuation frequency
Roadmap (Key Topics)
Wireless Transmission
Medium Access Control
Telecommunication Systems
Satellite Systems
Broadcast Systems
Wireless LAN
Mobile Network Layer
Mobile Transport Layer
Support for Mobility
Key Points to Take Away We want World Domination! (Or a bit more modest:
“mobile and wireless will dominate the future Internet & computing world”)
We are still in the beginning: except many more standards & technologies some competing, some collaborative efforts many many challenges (good for researchers!) you will and won’t see thousands of systems deployed and
used on daily basis
Computer Networks: every CS(E) person should know basics of networking and the Internet
Mobile/Wireless: more details about the cutting edge of networking (as consumer/developer/researcher/…)