Apr 19, 2023 UCSC CMPE257 1

CMPE 257: Wireless Networking

Disruption Tolerant Networking

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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

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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)

14UCSC CMPE257Apr 19, 2023

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

Vehicular Grid as Opportunistic Ad Hoc Net

(Source: M. Gerla, UCLA)

Hot Spot

Hot Spot

PowerBlackout

ST O P

PowerBlackout

ST O P

Vehicular Grid as Emergency Net

(Source: M. Gerla, UCLA)

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/