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8/26/08
Mobile Computing and
Wireless Communications
CSE 40814/60814
Fall 2008
Course Overview
  Instructor: Christian Poellabauer
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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
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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
Mobile Computing
Wireless Communication
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Applications
Location-awareness
Mobility Support
Security
Resource Management
Network Protocols
Broadcast
Technologies
Standards
Wireless Medium
Overview
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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
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small, cheap, portable, replaceable - no more separate devices
  Technology is in the background
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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
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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:
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user mobility: users communicate (wirelessly) “anytime, anywhere, with
anyone”
device portability: devices can be connected anytime, anywhere to the
network
  Wireless vs. mobile
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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:
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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...
UMTS, WLAN,
DAB, DVB, GSM,
cdma2000, TETRA, ...
ad
c
ho
Personal Travel Assistant,
PDA, Laptop, GSM, UMTS,
WLAN, Bluetooth, ...
A Business Man’s Morning
DSL/WLAN
3 Mbit/s
GSM/GPRS 53 kbit/s
Bluetooth 500 kbit/s
UMTS, GSM
115 kbit/s
LAN
100 Mbit/s,
WLAN
54 Mbit/s
UMTS
2 Mbit/s
GSM/EDGE 384 kbit/s,
DSL/WLAN 3 Mbit/s
GSM 115 kbit/s,
WLAN 11 Mbit/s
UMTS, GSM
384 kbit/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
PDA
•  graphical displays
•  character recognition
•  simplified WWW
Laptop/Notebook
•  fully functional
•  standard applications
Sensors,
embedded
controllers
Smartphone
•  tiny keyboard
Mobile phones
•  simple versions
•  voice, data
of standard applications
•  simple graphical displays
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
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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
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higher probability, has to be included in advance into the design (e.g.,
defects, theft)
  Limited user interfaces
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compromise between size of fingers and portability
integration of character/voice recognition, abstract symbols
  Limited memory
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limited usage of mass memories with moving parts
flash-memory as alternative
Wireless vs. Fixed Networks
  Higher loss-rates due to interference
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emissions of, e.g., engines, lightning
  Restrictive regulations of frequencies
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frequencies have to be coordinated, useful frequencies are almost all
occupied
  Low transmission rates
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tens of kbit/s to some Mbit/s
  Higher delays, higher jitter
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connection setup time with GSM in the second range, several hundred
milliseconds for other wireless systems
  Lower security, simpler active attacking
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radio interface accessible for everyone, base station can be simulated,
thus attracting calls from mobile phones
  Always shared medium
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secure access mechanisms important
Data Rates
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History of Wireless Networks
  Many people in history used light for communication
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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
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first demonstration of wireless
telegraphy
long wave transmission, high
transmission power necessary (> 200kW)
  1907 Commercial transatlantic connections
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huge base stations
(30 100m high antennas)
  1915 Wireless voice transmission New York - San Francisco
  1920 Discovery of short waves by Marconi
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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
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goal: pan-European digital mobile phone system with roaming
  1983 Start of the American AMPS (Advanced Mobile Phone System,
analog)
  1992 Start of GSM
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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
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IEEE standard, 2.4 - 2.5GHz and infrared, 2Mbit/s
already many (proprietary) products available in the beginning
  1998 Specification of GSM successors
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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
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IEEE standard 802.11b, 2.4-2.5GHz, 11Mbit/s
Bluetooth for piconets, 2.4GHz, <1Mbit/s
Decision about IMT-2000
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Start of WAP (Wireless Application Protocol) and i-mode
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several “members” of a “family”: UMTS, cdma2000, DECT, …
first step towards a unified Internet/mobile communication system
access to many services via the mobile phone
2000 GSM with higher data rates
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HSCSD offers up to 57,6kbit/s
first GPRS trials with up to 50 kbit/s (packet oriented!)
UMTS auctions
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Iridium goes bankrupt
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hype followed by disillusionment (100 billion Euros paid in Europe for licenses)
2001 Start of 3G systems
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Cdma2000 in Korea, UMTS tests in Europe, Foma (almost UMTS) in Japan
History of Wireless Networks
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2002
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WLAN draft for 250 Mbit/s (802.11n) using MIMO
WPA2 mandatory for Wi-Fi WLAN devices
2007
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WiMax starts as DSL alternative
first ZigBee products
2006
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WLAN hot-spots start to spread
2005
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over 3.3 billion subscribers for mobile phones
2008
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“real” Internet widely available on mobile phones (standard browsers, decent data rates)
Overview of Developments
cellular phones
1981:
NMT 450
satellites
1986:
NMT 900
1992:
GSM
1994:
DCS 1800
analog
1984:
CT1
1987:
CT1+
1988:
Inmarsat
-C
1991:
CDMA
1991:
D-AMPS
1993:
PDC
2000:
GPRS
1989:
CT 2
1992:
Inmarsat-B
Inmarsat-M
1991:
DECT
1998:
Iridium
digital
199x:
proprietary
1997:
IEEE 802.11
1999:
802.11b, Bluetooth
2000:
IEEE 802.11a
2001:
IMT-2000
4G – fourth generation: when and how?
wireless
LAN
1980:
CT0
1982:
Inmarsat
-A
1983:
AMPS
cordless
phones
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
Application
Transport
Transport
Network
Network
Data Link
Data Link
Data Link
Data Link
Physical
Physical
Physical
Physical
Radio
Network
Network
Medium
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Influence of Mobile Communication
to Layer Model
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
Application layer
Transport layer
Network layer
Data link layer
Physical layer
Roadmap (Key Topics)
Support for Mobility
Mobile Transport Layer
Mobile Network Layer
Telecommunication
Systems
Satellite
Systems
Broadcast
Systems
Wireless
LAN
Medium Access Control
Wireless Transmission
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:
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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/…)
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