Past, Present, and
Future of Mobile Computing
Yu Cai
Department of Computer Science
University of Colorado at Colorado Springs
6/2/2005
Yu Cai/MTU Talk
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Presentation outline
Introduction
Past
on mobile computing
of mobile computing
Present
of mobile computing
* Wireless LAN
* GSM/GPRS/CDMA
*Bluetooth
* Mobile IP
* Mobile Ad Hoc Network (MANET)
* PDA/SmartPhone/Laptop * Sensor/Zigbee Mesh
* RFID
* Security
Future
6/2/2005
of mobile computing
Yu Cai/MTU Talk
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What is mobile computing?

Mobile computing is to describe technologies that
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enable people to access network services anyplace, anytime,
and anywhere,
with portable and wireless computing and communication
devices. --- (where is this referenced? Provide citation!)
Aspects of mobility

User mobility

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different geographical locations
different networks
different communication devices
different applications
Device portability


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Between
Between
Between
Between
Between different geographical locations
Between different networks
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Mobile Computing vs.
Ubiquitous Computing/Pervasive Computing


Mobile Computing is a generic term describing the application of
small, portable, and wireless computing and communication
devices. This includes devices like laptops with wireless LAN
technology, mobile phones, wearable computers and Personal
Digital Assistants (PDAs) with Bluetooth or IRDA interfaces, and
USB flash drives.
Ubiquitous computing (ubicomp, or sometimes ubiqcomp)
integrates computation into the environment, rather than having
computers which are distinct objects. Another term for ubiquitous
computing is pervasive computing. Promoters of this idea hope
that embedding computation into the environment would enable
people to move around and interact with computers more naturally
than they currently do.
-- http://en.wikipedia.org/wiki/
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Applications of mobile computing

Vehicles
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transmission of news, road condition, weather, music via DAB
personal communication using GSM
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
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Medical
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Sales
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Nurses/Doctors in Medical offices are now using Wireless Tablet PCs/WLAN to
collect and share patient information.
Sales representatives are using Tablet PCs with Smart phones for presentation,
transmitting/access information among office, hotel, and customer location.
Emergencies
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Early transmission of patient data to the hospital, current status, first diagnosis
Provide mobile infrastructure in dealing with Natural Disaster (earthquake,
hurricane, fire), terrorist attacks, war, ...
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Natural evolution of computing
More
Flexible
Resource
Usage
Mobile Computing
LANs + WorkStations
Networking
Timesharing
Batch
Single User
OS
Freedom from Collocation
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Challenges in mobile computing
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Mobility means changes
Hardware
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Low bandwidth, high bandwidth variability
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Locality adaptation
Higher loss-rates, higher delays, more jitter

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Different devices, interfaces and protocols
Location awareness
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Devices more vulnerable, endpoint authentication harder
Heterogeneous network
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Kbit/s to Mbit/s, bandwidth fluctuation
Security risk
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Lighter, smaller, energy management, user interface
Connection setup time, hand-off
Restrictive regulations of frequencies
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Frequencies have to be coordinated
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History of wireless communication
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1896 Guglielmo Marconi,
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1907 Commercial Trans-Atlantic Wireless Service
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Huge ground stations: 30 x 100m antenna masts
1920 Discovery of short waves by Marconi
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First demonstration of wireless telegraphy
Based on long wave, requiring very large transmitters
Cheaper, smaller, better quality transmitters by vacuum tube
1982
1983
1992
1997
1998
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6/2/2005
Start of GSM in Europe (1G analog)
Start of AMPS in America (1G analog)
Start of GSM (2G digital)
Wireless LAN - IEEE802.11
Iridium satellite system
66 satellites
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History of wireless communication


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1999 Standardization of additional wireless LANs
 IEEE standard 802.11b
 Bluetooth
 WAP (Wireless Application Protocol): access to many
services via the mobile phone
2000 GSM with higher data rates (2.5G digital)
 HSCSD offers up to 57,6kbit/s
 First GPRS trials with up to 50 kbit/s
2001 Start of 3G systems
 IMT - 2000, several “members” of a “family”,
CDMA2000 in Korea, UMTS tests in Europe
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Overview of mobile devices
Pager
• receive only
• tiny displays
• simple text
messages
Sensors,
embedded
controllers
Smart phone
• voice, data
• simple graphical displays
Wearable device
• human wearable
• non standard I/O
Laptop
• fully functional
• standard applications
PDA
• graphical displays
• character recognition
performance
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Overview of development
cellular phones
1981:
NMT 450
1G
2G
1984:
CT1
1987:
CT1+
1988:
Inmarsat-C
1991:
CDMA
1991:
D-AMPS
1992:
Inmarsat-B
Inmarsat-M
1993:
PDC
1994:
DCS 1800
1989:
CT 2
1991:
DECT
1998:
Iridium
2000:
GPRS
2.5G
199x:
proprietary
1997:
IEEE 802.11
1999:
802.11b, Bluetooth
2000:
IEEE 802.11a
2003:
IEEE 802.11g
20??
Fourth Generation?
analogue
digital
6/2/2005
wireless
LAN
2007?:
IEEE 802.11N
2001:
IMT-2000
3G
4G?
1980:
CT0
1982:
Inmarsat-A
1983:
AMPS
1986:
NMT 900
1992:
GSM
cordless
phones
satellites
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Overview of wireless services
Data Rates
10 Mbps
Wireless
LAN
IR
1 Mbps
Cellular: GSM,
GPRS, CDMA,
50 Kbps
Satellite
10 Kbps
Wide
Local
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Coverage
Area
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Wireless LAN


IEEE 802.11 standard: a family of specifications for
wireless LAN technology. The IEEE accepted the
specification in 1997.
802.11 specifies an over-the-air interface between a
AP: Access Point
wireless client and a base
station or between
two
AP
wireless clients.

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Wired
AP2 Mbps in
802.11: up to
the Network
2.4 GHz band. AP
802.11b: up to 11 Mbps in the 2.4 GHz band.
802.11a/g: up to 54 Mbps in the 5/2.4 GHz band.
802.11n: up to 220+ Mbps in the 2.4/5 GHz band (two proposals
not approved yet). Vendors already selling 802.11pre-n devices.
802.11 promises true vendor interoperability. Every
vendor must have a viable 802.11 product strategy.
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Wireless LAN Security

WEP: Wired Equivalent Privacy.
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A basic wireless LAN security mechanism.
Easy to set up, commonly used.
Don’t rely on WEP for wireless security. There are a number of
flaws in the WEP.
Many wireless home networks don’t even use WEP,
which makes bad situation worse.
MAC address based access control mechanism doesn’t
work.
Use other security mechanisms such as VPN, PEAP and
TTLS.

6/2/2005
Research project on PEAP / TTLS in our research group in
University of Colorado.
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Wireless Ad Hoc Network

Wireless Ad Hoc Network (peer to peer)
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Mobile Ad Hoc Networks (MANET)
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A collection of autonomous nodes that communicate with each
other by forming a multi-hop radio network in a decentralized
manner.
No infrastructure, no default router available
“every” node needs to be a router
Host movement frequent
Topology change frequent
Wireless Ad Hoc Sensor Networks
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A number of sensors spread across a geographical area.
Limited resources on sensors
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Mobile IP
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Mobile IP is designed to allow mobile device users to
move from one network to another while maintaining
their permanent IP address.
Motivation:
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Changing the IP address is not desired when host moves.
However, traditional scheme requires to change IP address
when host moves between networks.
Mobile IP provides an efficient, scalable mechanism for
node mobility within the Internet. Mobile IP allows
moving devices to maintain transport and higher-layer
connections while moving.
Applications:

6/2/2005
Mobile IP is most often found in wireless WAN environments
where users need to carry their mobile devices across multiple
LANs with different IP addresses.
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Mobile IP: Basic Idea
Mobile Node (MN)
Home Agent (HA)
2
home network
3
Internet
receiver
foreign
network
COA: ?
Foreign Agent (FA)
1
sender
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1. Sender sends to the IP address of MN,
HA intercepts packet (proxy ARP)
2. HA tunnels packet to COA, here FA,
by encapsulation
3. FA forwards the packet to the MN
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Mobile IP: Basic Idea
HA
1
home network
MN
sender
Internet
FA
1. Sender sends to the IP address
of the receiver as usual,
FA works as default router
CN
6/2/2005
foreign
network
receiver
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Bluetooth
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Bluetooth is used to connect and exchange information
between devices like PDAs, mobile phones, laptops, PCs,
printers and digital cameras wirelessly.
Named after a Denmark king Harold Bluetooth, who is
known for his unification of previously warring tribes.
Low-cost, short range (up to 10m), low power
consumption, license-free 2.45 GHz band.
Using the same frequency range, Bluetooth differs from
Wi-Fi in that

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Different multiplexing schemes.
Wi-Fi with higher throughput, greater distances, more expensive
hardware, and higher power consumption.
Applications:

Wireless mouse, wireless headset
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RFID: Radio Frequency Identification

RFID is a method of remotely storing and retrieving data
using devices called RFID tags.
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Categories:
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An RFID tag is a small object, such as an adhesive sticker, that
can be attached to or incorporated into a product.
RFID tags contain antennas to enable them to receive and
respond to radio-frequency queries from an RFID transceiver.
No line-of sight required (compared to laser scanners)
Withstand difficult environmental conditions (cold, frost etc.)
Active RFID: battery powered, distances up to 100 m
Passive RFID: operating power comes from the reader over the
air, distances up to 6 m
Applications:

6/2/2005
Automated toll collection: RFIDs mounted in windshields allow
commuters to drive through toll plazas without stopping
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GSM

One of the most popular standards for mobile phones in
the world.
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Formerly: Groupe Spéciale Mobile (founded 1982)
Now: Global System for Mobile Communication
European standard, moving to North America
More than one billion people use GSM phones as of
2005, making GSM the dominant mobile phone system
worldwide with about 70% of the world's market.
GSM is a cellular network, which means that mobile
phones connect to it by searching for cells in the
immediate vicinity.
One of the key features of GSM is the Subscriber
Identity Module (SIM), commonly known as a SIM card.
The SIM is a detachable smartcard containing the user's
subscription information and phonebook.
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GSM Overview
OMC, EIR,
AUC
HLR
GMSC
fixed network
NSS
with OSS
VLR
MSC
VLR
MSC
BSC
BSC
RSS
MS
MS
BTS
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Yu Cai/MTU Talk
RSS (Radio Subsystem)
NSS (Network and switching subsystem)
OSS (Operation Subsystem)
MS (Mobile Station)
BTS (Base Transceiver Station)
BSC (Base Station Controller)
MSC (Mobile Services Switching Center)
GMSC (Gateway MSC)
HLR (Home Location Register)
VLR (Visitor Location Register)
EIR (Equipment Identity Register)
AUC (Authentication Center )
OMC (Operation and Maintenance
22Center )
GPRS
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GPRS: General Packet Radio Service
It is a mobile data service available to users of GSM
mobile phones. It is often described as "2.5G“.
GPRS is packet-switched which means that multiple
users share the same transmission channel, only
transmitting when they have data to send.
GPRS provides moderate speed data transfer, by
allocating unused cell bandwidth to transmit data.
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Poor bit rate in busy cells
Usually, GPRS data is billed per kilobytes of information
transceived
In 3G mobile systems like UMTS (Universal Mobile
Telecommunication System), voice and data services will
be mixed in a normal communication.
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PDA
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Personal digital assistants (PDAs or palmtops)
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The currently major PDA operating systems are:
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handheld devices that were originally designed as personal
organizers, but became much more versatile over the years.
A basic PDA usually includes a clock, date book, address book,
task list, memo pad and a simple calculator.
One major advantage of using PDAs is their ability to
synchronize data with desktop, notebook and desknote
computers.
Palm OS by PalmSource, Inc
Windows Mobile (Windows CE) by Microsoft
BlackBerry by Research In Motion
Symbian by a group of companies
According to a Gartner market study, the overall market
for PDAs shrunk by 5% in the first quarter (Q1) of 2004,
compared to Q1 2003. Yu Cai/MTU Talk
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6/2/2005
Satellite Systems
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Like cellular systems, except that the base stations (i.e.,
satellites) move as will as mobile devices
Satellite coverage attractive for areas of world not well
served by existing terrestrial infrastructure: ocean areas,
developing countries
IRIDIUM
 Motorola
 Voice, Data (2.4 kbps), Fax, Location Services
 66 satellites in 6 polar orbits (780 km)
 Failed project
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Future mobile and wireless networks
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Shift industrial paradigm from piecewise solutions to
end-to-end information systems
Improved radio technology and antennas
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Core network convergence
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IP-based, quality of service, mobile IP
Ad-hoc technologies
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smart antennas, beam forming, multiple-input multiple-output
(MIMO) 802.11N
dynamic spectrum allocation
spontaneous communication, power saving, redundancy
Simple and open service platform
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6/2/2005
intelligence at the edge, not in the network (as with IN)
more service providers, not network operators only
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Integrated mobile computing
Integration of heterogeneous fixed and
mobile networks with varying
transmission characteristics
regional
vertical
handover
metropolitan area
campus-based
in-car,
in-house,
personal area
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Yu Cai/MTU Talk
horizontal
handover
27
IP-based next generation network ?
SS7 signalling
server farm,
gateways, proxies
PSTN, CS
core
broadcast
gateways
MSC
IP-based
core
SGSN
GSM
BSC
firewall, GGSN,
gateway
router
Internet
access
points private
private
WLAN
WPAN
RNC
UMTS
public
WLAN
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Literature
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Jochen Schiller – Mobile Communications
Ivan Stojmeniovic – Handbook of Wireless Networks and Mobile Computing
Andrew Tanenbaum – Computer Networks
James D. Solomon – Mobile IP, the Internet unplugged
Charles E. Perkins – Ad-hoc networking
Papers, papers, papers, …
Mobile Computing Courses
 MIT: http://nms.lcs.mit.edu/6.829-f01/
 Stanford: http://www.stanford.edu/class/cs444n/
 UC Berkley: http://www.cs.berkeley.edu/~adj/cs294-1.f00/
 UT Austin: http://www.cs.utexas.edu/users/ygz/395T/
 http://kunz-pc.sce.carleton.ca/sce536/
 http://www.cs.unc.edu/~dewan/290/s02/lectures/lectures.htm
 http://www.cs.arizona.edu/classes/cs630/fall01/630-1/contents.htm
 http://www.cs.ucsb.edu/~cs290i_mc/index.html
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Thank you!
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