Mar 23, 2022 UCSC CMPE257 1 CMPE 257: Wireless Networking Disruption Tolerant Networking
Dec 31, 2015
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Outline
Motivation Open problems Examples of state of the art
and future work
Key Message: There is much to be done!
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Motivation Provide access to information, people, and
services even when physical connectivity is sporadic or disrupted frequently.
Opportunistic use of available resources Example applications:
Interplanetary internetworking Networks in battlefield and disaster relief Environmental and wild-life monitoring Developing regions Vehicular networks Peer-to-peer systems and opportunistic
messaging
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•End-to-end information flow across the solar system
•Layered architecture for evolvability and interoperability
•IP-like protocol suite tailored to operate over long round trip light times
•Integrated communications and navigation services
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Extremely LongPropagation Delays
Planet RTTmin RTTmax
Mercury 1.1 30.2
Venus 5.6 35.8
Mars 9 55
Jupiter 81.6 133.3
Saturn 165.3 228.4
Uranus 356.9 435.6
Neptune 594.9 646.7
Pluto 593.3 1044.4
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Challenges with Interplanetary Internet
Extremely long and variable propagation delays
Asymmetrical forward and reverse link capacities
Extremely high link error rates Intermittent link connectivity, e.g., Blackouts Power, mass, size, and cost constraints for
communication hardware and protocol design
However, links have predictable on-off schedules!
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History of Delay Tolerant Networking (DTN)
(Source: “Delay Tolerant Networking,” S. Burleigh et al, 24 April 2003)
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(Source: “Delay Tolerant Networking,” S. Burleigh et al, 24 April 2003)
History of Delay Tolerant Networking (DTN)
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Environmental Monitoring
(source: EPFL)
(source: Intel)
Link on-off schedules are random because of subject under observation or equipment constraints.
Some nodes can move randomly or with controlled/known routes
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Battlefield and Disaster Relief
End-to-end connectivity need not ever exist and links (contacts) may not be suitable for
schedules
z
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Healthcare Monitoring Networks
Personal area networks
Subjects may have on-off connectivity with environment
Self configuring
Source: Wellness environments
VANETs: Car to Car Communication
Vehicle type: Cadillac XLRCurb weight: 3,547 lbsSpeed: 65 mphAcceleration: - 5m/sec^2Coefficient of friction: .65Driver Attention: YesEtc.
Vehicle type: Cadillac XLRCurb weight: 3,547 lbsSpeed: 45 mphAcceleration: - 20m/sec^2Coefficient of friction: .65Driver Attention: NoEtc.
Vehicle type: Cadillac XLRCurb weight: 3,547 lbsSpeed: 75 mphAcceleration: + 20m/sec^2Coefficient of friction: .65Driver Attention: YesEtc.
Vehicle type: Cadillac XLRCurb weight: 3,547 lbsSpeed: 75 mphAcceleration: + 10m/sec^2Coefficient of friction: .65Driver Attention: YesEtc.
Alert Status: None
Alert Status: Passing Vehicle on left
Alert Status: Inattentive Driver on Right
Alert Status: None
Alert Status: Slowing vehicle aheadAlert Status: Passing vehicle on left
(Source: M. Gerla, UCLA)
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Dedicated Short Range Communications (DSRC)/802.11p
Car-Car communications in 5.9Ghz frequency band Range of 1 Km Node speeds up to 85mph Data rates of 6 to 27 Mbps (depending on range) Derived from 802.11a three types of channels: Vehicle-Vehicle service, a
Vehicle-Gateway service and a control broadcast channel . Ad hoc mode and infrastructure mode 802.11p: IEEE Task Group that intends to standardize
DSRC for Car-Car communications Same problems as 802.11a/b/g in MANETs
Hot Spot
Hot Spot
PowerBlackout
ST O P
PowerBlackout
ST O P
Vehicular Grid as Emergency Net
(Source: M. Gerla, UCLA)
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Commercial Market?“Opportunistic” MANETs
Connectivity is a problem because of market penetration and node density
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Example Application:A Self-Organizing Wireless Messaging Network
(SOWER)
h
Each user owns:
m
home device
mobile device
Home devices form a wireless backbone for message transmission
Home devices are: power plugged – always on static devices same radio as mobiles
Source: SOWER: “Self- Organizing Wireless Network for Messaging,” Mark Felegyhazi, Srdjan Capkun and Jean-Pierre Hubaux , Tech Rept. IC/2004/62
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Penetration RequirementsScenario
2260
small(Berkeley)
historic(Rome)
modern(Berlin)
ultra-modern(Manhattan)
Population density(persons/km2)
Required device density
(devices/km2)
Required market penetration
(simulation for 100mW)
Required market penetration
(calculated for 1W, α=5)
8177 12500 25850
380 700 3000 5000
0.168 0.086 0.24 0.193
0.04 0.02 0.06 0.05
Source: SOWER: “Self- Organizing Wireless Network for Messaging,” Mark Felegyhazi, Srdjan Capkun and Jean-Pierre Hubaux , Tech Rept. IC/2004/62More information: http://lcawww.epfl.ch/felegyhazi/