Redes Inalámbricas – Tema 1 General concepts

Redes Inalámbricas – Tema 1
General concepts
An overall view of:
Technologies
MANETs networks
Applications
Devices
References
Acknowledgments
A
k
l d
t
Mark Weiser
Vint Cerf
Jim Kurose, Keith Ross, “Computer Networking: A Top Down Approach Featuring the Internet, 2nd
edition. Addison
Addison-Wesley,
Wesley, July 2002
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Redes Inalámbricas – Tema 1
General concepts
Technologies
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Various types of wireless technologies
Network telephony. Various generations:
GSM
UMTS
GPRS, HSCSD;
HSDPA
Satellites:
Satellites Geostationary Earth Orbit
(GEO)
Example: Inmarsat
Satellites Low-Earth Orbit (LEO)
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Example : Iridium (66 satellites) (2.4
Kbps data)
Infrared: IrDA
(
)
Ultra-Wide Band (UWB)
RFID
Zigbee
…
WiFi
WiMax
Bl t th
Bluetooth
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Wireless Data Networks
Wireless networks are the best option for mobile devices:
Easy instalation
no problem with cables
Systems easily expandable according to the needs
Shared acces to Internet
There is no need to "plug" and "unplug"
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Personal Area
Local Area
Wireless LAN
PAN
Bluetooth
IEEE 802.11,
HiperLAN/2
Wide Area
Cellular Systems
GSM,
GPRS, EDGE
UMTS
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Uses of WLANs
“CORPORATE CAMPUS”
“HOME OFFICE”
• COMMON AREAS,
• MEETING ROOMS,
• LABORATORIES,
• TEMPORARY OFFICE
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“HOT SPOTS”
• AIRPORTS
• HOTELS
• CONVENTION CENTER
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Uses of WPAN
Mobile/Smart HH
STB/Media Center
PC
BT Model
UWB Model
Photo/Printer
Mass Storage
Substitute cables
Personal ad hoc connectivity
y
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HDTV
KB, Mouse
DVC
Voice, Stereo Audio
DSC
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Mobility
There are several types of mobility
y
mobilityy ((of the devices))
Physical
off line connectivity: portable
on line connectivity : mobile
Logical mobility:
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Of the processes
Of the applications
pp
“ubiquitous
q
computing”
p
g
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Mobility and the applications
Bandwidth variability
Applications should adapt. E.g., a videoconferencing application could vary the
image size or its quality when varying the bandwidth.
bandwidth
Disconnection
Allow asynchronous operations, pre-fetching, caching, weak consistency, ...
Security and privacy
The wireless channels are prone to "wiretapping''(snooping)
Who
o sshould
ou d be g
given
e access to tthe
e location
ocat o information?
o at o How
o much
uc accu
accurate
ate
should be this information?
Energy management:
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stop discs
discs, turn off the screen
screen, standby mode of the CPU
CPU, put to sleep the network
card, …
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General view
“Mobile ad hoc networking: imperatives and challenges”, Imrich Chlamtac, Marco Conti, Jennifer J.-N. Liu, Ad Hoc Networks, Elsevier, 1 (2003).
Redes Inalámbricas – Tema 1
General concepts
Devices
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Sensors
Mica Hardware Platform: The Mica sensor node (left) with the Mica
Weather Board developed for environmental monitoring applications
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Commercial Motes
Processor:
Memory:
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Radio:
Antenna:
OS
OS:
Battery:
4MHz, 8bit CPU
Prog RAM Memory (128 KB), Data RAM (4KB)
On-Board
On
Board Flash (512 KB)
916 Mhz, 52K bps (150-300m max range)
On-board, optional external
Ti OS from
TinyOS
f
Berkeley
B k l
2xAA, coin cell (sleep often, sleep deep)
http://www.xbow.com
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Mobile devices: PDA and phones
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Mobile devices: PDA and phones
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Mobile devices: notebooks/laptops
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Mobile devices : tablet PC
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More devices (Information/Internet Appliances)
Web-enabled toaster+weather forecaster
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IP picture frame
http://www.ceiva.com/
World’s smallest web server
http://www.webservusb.com/
p
Screenfridge
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More devices (Information/Internet Appliances)
Redes Inalámbricas – Tema 1
General concepts
MANETs networks
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Mobile Ad-hoc Networks (MANETs)
Networks formed by mobile wireless nodes.
g infrastructure
Do not use anyy existing
There are hybrid solutions known as "mesh networks“
In a MANET mobility has a crucial importance.
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routes vary over time
i
partitioning
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Why ad hoc networks?
The ad hoc networks can be deployed in a flexible manner in
environments that have no fixed infrastructure
Having a fixed wired infrastructure or access points is not always
possible or feasible
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It is not economically viable or interesting
It is not practical in temporary environments
It may have been destroyed, for example, due to natural disasters
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A “clear” example: vehicular networks
About “smart cars” and “smart roads”.
On-board systems “talk” with the “road”.
They car offer:
Cooperative driver assistance:
Emergency notification
E
tifi ti
Overtaking assistance
Obstacle warning
Decentralized floating car data:
Traffic jam monitor
Dynamic navigation
Route weather forecast
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User communications and
information services:
Hot-spot Internet access
Inter-vehicle chat
Distributed games
g
Redes Inalámbricas – Tema 1
General concepts
Applications: UBIQUITOUS COMPUTING
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Ubiquitous Computing
Mark Weiser
– The father of “Ubiquitous Computing” (1988)
Definitions
Ubiquitous
q
computing
p
g is the method of enhancing
g computer
p
use byy making
g manyy
computers available throughout the physical environment, but making them
effectively invisible to the user
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– Mark Weiser
Mark Weiser (1952-1999) was the chief technology officer at Xerox’s Palo Alto Research Center
(Parc). He is often referred to as the father of ubiquitous computing. He coined the term in 1988 to
describe a future in which invisible computers, embedded in everyday objects, replace PCs. Other
research interests included garbage collection, operating systems, and user interface design. He
received his MA and PhD in computer and communication science at the University of Michigan, Ann
Arbor. After completing his PhD, he joined the computer science department at the University of
Maryland College Park
Maryland,
Park, where he taught for 12 years
years. He wrote or cowrote over 75 technical
publications on such subjects as the psychology of programming, program slicing, operating systems,
programming environments, garbage collection, and technological ethics. He was a member of the
ACM, IEEE Computer Society, and American Association for the Advancement of Science. Weiser
passed away in 1999. Visit www.parc.xerox.com/csl/members/weiser or contact
communications@parc.xerox.com for more information about him.
M. Weiser, The Computer for the 21st Century Scientific American, 1991
Mark Weiser (1952(1952-1999)
http://www--sul.stanford.edu/weiser/
http://www
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Ubiquitous Computing
What Ubiquitous Computing is!
Information technology everywhere
Is a paradigm shift where technology becomes virtually
invisible in our lives
“Calm Technology”
It needs
1. Smart Objects embedded processors
2. Wireless Technology to interconnect them
What Ubiquitous Computing is not!
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Ubiquitous Computing: And old vision
Mobility itself doesn’t lead to UbiComp
Multimedia itself doesn’t lead to UbiComp either
Virtual reality neither
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Virtual reality vs ubiquitous computing
Virtual Reality
World in the computer
Ubiquitous Computing
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Computers in the world
(paradigm inversion)
drawing computers out of their
electronic shells
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The new paradigm
Environment-centric instead of computer-centric or Context-centric
instead of desktop-centric
Generic Features
1 Transparent
1.
T
t interfaces
i t f
Invisible interfaces that Provide
interaction between user and application
• Ubiquitous Computing
—
Human - environment
—
Flexible and adaptable services
• Context-Aware Applications.
Applications
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Smart Home. A realistic
scenario?
Transparent
Interfaces
Awareness of
Context(s)
Capture Experience
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The new paradigm
Generic Features
2. Awareness of context
Public
Di l
Display
Space
es
Sources
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Sin
nks
Context
information about the environment with which the
application is associated.
LOCATION and TIME are simple examples of context !
Computing context vs User context vs physical context ?
Auto
Di
Diary
CAApp
Context
B
Browser
Why is context needed?
Context
C t t
Context
Data
Data Layer
Layer
Sensor
Environment
Preferences
Manual
Input
p
Generic Context Model
Transparent
Interfaces
Awareness of
Context(s)
Capture Experience
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The new paradigm
Generic Features
3. Capture experience
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To capture our day-to-day experience and make it available for future use.
To acquires knowledge from places visited to server future visitors
Research challenges
g
Multiple streams of information
Their time synchronization
Their correlation and integration
Smart carpets (Infineon)
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Smart Devices
MediaCup (Teco, MediaCup)
Sensing, processing, and communication capabilities
Periodically broadcasting state of cup
Applications:
Visualizing
g state of cup
p
Infering and indicating meetings through aggregation of cups
…
MIT Media
M di Lab
L b – Shoes
Sh
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Broadcast ID every 3 to 5 steps
Applications
pp
…
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Applications
Infostations
Used in many modern museums
Infostation near an exhibit provides
detailed information
Visitors approach infostation
Offer of information
User preferences
Language
Level of detail
…
Oceanis, Wilhelmshaven
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More examples at MIT
http://ttt.media.mit.edu/
Redes Inalámbricas – Tema 1
General concepts
Applications: RURAL COMMUNICATIONS
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Global survey on rural communications
Rural communications on the global agenda
Connecting villages with Information and Communication Technologies (ICT) and
establishing
t bli hi community
it access points
i t
Benefits
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E business and e
E-business
e-commerce
commerce could play an important role in enabling local artisans
to reach national and international markets
Over 40% of the world’s population lives in rural and remote areas of developing
countries and have difficult or no access to even basic telecommunications services.
services
Development of telecommunications in rural and remote areas, therefore forms an
important mission of the ITU Development sector.
Yasuhiko
Y
hik K
Kawasumi,
mi “R
Rurall communications
mm ni ti n on
n th
the global
l b l agenda,
nd ” Global
Gl b l Survey
S
on
n Rural
R
l
Communications for the ITU-D on Communications for rural and remote areas.
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Rural populations and their ICT needs
Needs of rural people in connection with e-services
E-health, e-education and e-administration top the list as primary needs
E-business and e-banking also scored highly
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ITU-D global survey, Doc 111/SG2
For many rural areas, electricity
supply is simply non-existent or
insufficient
T l
Telemedicine
di i
T
Training
i i iin Bh
Bhutan
t
by
b Tokai
T k i University:
U i
it Tokai University Institute of Medicall
Sciences donated the medical equipments with ICT functions and provided the training on the use of
equipments. Tokai University Second Opinion center provides the assistance service over the internet
when requested by the Bhutanese ends.
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Optimal Technologies to connect Rural Communities
Question 1: What are the requirements for communications system in
rural areas
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Implementation should be possible at a low cost in areas where population density
is low
The system
y
can be easilyy installed,, even in remote and inaccessible locations
System operation and maintenance may be carried out even where qualified
technical personnel are scarce
Implementation should be possible even when basic infrastructure such as mains
electricity, running water, paved road networks, etc., are absent
Long life cycles
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Optimal Technologies to connect Rural Communities
Question 2: What are the choices of technologies for communications
in rural areas
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Mobile communications system (2G,GSM)
Satellite communications system (VSAT)
Terrestrial wireless communications system
Wi-Fi, Wi-Max, 802.16
Copper wire including power line
Th final
The
fi l reportt off ITU Focus
F
G
Group 7 on “N
“New
technologies for rural applications” (2001)
recommended (WiFi) based on the IEEE 802.11 b/g
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Optimal Technologies to connect Rural Communities
Question 3: What is the advantage of wireless technologies for
communications in rural areas
Provide significant life time cost benefits in rural areas in cases where cable
deployment is uneconomic.
p
y installation in harsh terrain and extremelyy remote areas,,
Provide easyy and speedy
smaller investment increments and avoidance of copper cable theft.
Provide lower maintenance cost and greater network flexibilities
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Question 4: How to finance the rural projects
Giving priority to the rural communications projects funding system.
Subsidy by the Universal Service Funds.
Partnership with funding institutions and private sectors
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Optimal Technologies to connect Rural Communities
Question 5: What are the barriers for communications in the
environment of rural areas
Scarcity and absence of reliable electricity supply, water, access roads and regular
transport
p
Scarcityy of technical personnel
Difficult topographical conditions (lakes, rivers, hills, mountains, or deserts, etc.)
Severe climatic conditions that make critical demands on the equipment.
Low level of economic activity mainly based on agriculture,
agriculture fishing,
fishing handicrafts,
handicrafts
etc.
Low per capita income
Underdeveloped
d d
l
d sociall infrastructure
f
(health,
(h l h education)
d
)
Low population density
Low literacyy rate
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El Programa Telecentros
¿Qué es?
El programa Telecentros se ha dirigido a los municipios de zonas rurales y a
núcleos
ú l
urbanos
b
desfavorecidos,
d f
id
a través
t é de
d las
l Diputaciones,
Di t i
Cabildos
C bild y Consejos
C
j
insulares o, en su caso, Comunidades Autónomas uniprovinciales. La actuación
tuvo como principal objetivo facilitar el acceso a las nuevas tecnologías tanto a las
poblaciones rurales
ales como a los colecti
colectivos
os menos integ
integrados,
ados a fin de lograr
log a su
s
participación efectiva en la Sociedad de la Información.
La actuación tiene como principal objetivo facilitar el acceso a las nuevas
t
tecnologías
l í tanto
t t a llas poblaciones
bl i
rurales
l como a los
l colectivos
l ti
menos
integrados, a fin de lograr su participación efectiva en la Sociedad de la
Información.
Actuaciones:
i
Conexiones a Internet de banda ancha en zonas rurales
y urbanas desfavorecidas.
Equipamiento de los Centros de Acceso Público a Internet.
Servicios de instalación, mantenimiento y atención al usuario.
Servicios de control y gestión del Centro
Centro.
Portales de servicios a poblaciones rurales.
Servicios de dinamización y formación
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EU y las redes rurales
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Mesh Networks
Features
Multi-hop Networks
Automatic organization and maintenance
Support for mobility (clients)
Integration of technology access
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MIT Roofnet
MIT Roofnet: http://pdos.csail.mit.edu/roofnet/doku.php
Wireless access to the MIT Computer Science Lab
1,25 squared miles
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MIT Roofnet: Distribution
of nodes and quality of the
links
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guifi.net
Public WiFi network deployed basically in Cataluña
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Other proposals
Kingsbridge Link
http://www.kblink.co.uk/
Based on Linksys WRT54g
panOULU
http://www.panoulu.net/
Finland
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Meraki
http://meraki.com/
http://meraki
com/
San Francisco
Fon
http://www fon com/es/
http://www.fon.com/es/
Redes Inalámbricas – Tema 1
General concepts
Applications: VANETs
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Motivation
Safety and transport efficiency
In Europe around 40,000 people die and more than 1.5 millions are injured every
year on the
th roads
d
Traffic jams generate a tremendous waste of time and of fuel
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Most of these problems can be solved by providing appropriate
information to the driver or to the vehicle
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Passive Approach is not Enough
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On foggy days
What’s in
front of
that bus ?
On rainy days
What’s
behind
h n th
the
bend ?
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Vehicle Communication (VC)
VC promises safer roads,
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… more efficient driving,
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Vehicle Communication (VC)
… more fun,
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… and easier maintenance.
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Technologies for traffic safety systems
Sensors
Radars send narrow microwave beams (lidars – lazer beams) that are reflected
f
from
objects
bj t and
d then
th received
i d back
b k by
b the
th radars
d
Based on this information, the relative position and velocity of other objects can
be determined
Limitations: local perception (require line-of-sight), utilization-related problems
(rain and snow, dust and mud), cost and integration within vehicles
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Computer vision
Stereo cameras monitor the environment around a vehicle, and image processing
is used for determining dangerous situations, such as a possible collision or a
vehicle that dangerously approaches the lateral side of a road
Limitations: first 2 in sensors, also low speed of image processing and large
number of false alarms
Solution to these limitations – Vehicular communication…
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Smart Vehicle (OBUs)
Event data recorder (EDR)
Forward radar
Positioning system
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Communication
facility
Rear radar
Di l
Display
C
Computing
ti platform
l tf
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Lot of Involved Technologies
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Vehicular Ad Hoc Network (VANET)
Ad-Hoc Network:
A network with minimal or no infrastructure
Self-organizing
Each node can act as the source of data, the destination for data and a network
router
Vehicular Ad Hoc network (VANET)
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Uses equipped vehicles as the network nodes
N d move at will
Nodes
ill relative
l i to each
h other
h but
b within
i hi the
h constraints
i
off the
h road
d
infrastructure
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VANETs vs MANETs
Vehicular ad-hoc network (VANET) are a special case of Mobile ad-hoc
networks (MANET)
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VANET constrained by
Predefined roads (e.g. one-way and multi-lane)
Vehicle velocities restricted by speed limits
Level of congestion in roads (e.g. urban or suburban)
Traffic control mechanisms (e.g. traffic light)
VANET advantage by
Rechargeable
g
source of energy
g
Equipped with devices with potentially longer transmission ranges. (e.g. adopt
WAVE and WiMAX)
etc.
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VANETs vs MANETs
Rapid Topology Changes
High relative speed of vehicles => short link life
Frequent Fragmentation
Chunks of the net are unable to reach nodes in nearby regions
Small Effective Network Diameter
A path may cease to exist almost as quickly as it was discovered (reactive routing)
Limited Redundancy
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The redundancy in MANETs is critical to providing additional bandwidth
In VANETs the redundancy is limited both in time and in function
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Lot of Involved Parties
Redes Inalámbricas – Tema 1
General concepts
References
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Official organizations
ITU (before CCITT) in Europe:
organized in: Study Groups
Working Parties
Expert Teams
ISO is a member of ITU-T and includes ANSI, AENOR, UNI, DIN, ...
organized
i d in:
i TC
SC
WG
TC-97: Computers and Information processing
phases: CD (committee
p
(
draft))
DSI ((draft international standard))
(international standard)
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Oth
Other:
IEEE ACM,
IEEE,
ACM NIST,
NIST ...
IS
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Standards en Internet
de-facto standards
“Rough consensus and running code”, D. Clark
Defined in documents called RFCs (Request For Comments) available on line:
http://www.rfc-editor.org/
IAB
1983
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1989
IRTF
~1991
(Internet Architecture Board)
IETF
Internet Society
Phases: Proposed standards
Draft Standard Internet Standard
Before getting to RFC we use Internet-Drafts which are working documents of
the Internet Engineering Task Force (IETF), its areas, and its working groups.
https://datatracker.ietf.org/drafts/
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Where to find up-to-date research references
Journals and Magazines:
IEEE Network Magazine
IEEE C
Communications
i ti
Magazine
M
i
IEEE Wireless Communications Magazine
IEEE Pervasive Computing
IEEE/ACM T
Transactions
ti
on N
Networking
t
ki (TON)
IEEE Transactions on Mobile Computing
IEEE Journal on Selected Areas of Communications (JSAC)
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Conferences:
MOBICOM, MOBIHOC, PIMRC, MWCN...
ICC, ISCC, ICCN
GLOBECOM
INFOCOM
SIGCOMM
WWW
A good starting point ☺ http://www.grc.upv.es/
Web pages of research groups
Google…