Delay and Disruption Delay and Disruption Tolerant NetworksTolerant Networks

Mostafa AmmarMostafa AmmarCollege of Computing

Georgia Institute of TechnologyAtlanta, GA

In Collaboration: Ellen Zegura (GT), Brian Levine and Mark Corner (UMass)Funding: NSF, DARPA, Cisco

The “Traditional” Ad-Hoc Wireless Paradigm

The Network is “Connected” There exists a (possibly multi-hop) path

from any source to any destination The path exists for a long-enough period of

time to allow meaningful communication If the path is disrupted it can be repaired

in short order “Looks like the Internet” above the

network layer

The Rise of Sparse Disconnected Networks

Sparse Wireless Networks

Disconnected By Necessity By Design (e.g. for power considerations)

Disruption-Tolerant Networks (DTNs)Mobile

With enough mobility to allow for some connectivity over time

Data paths may not exist at any one point in time but do exist over time

New Communication Paradigms

Mobility used for connectivityNew Forwarding Paradigm Store Carry for a while forwardSpecial nodes: Transport entities that

are not sources or destinations

Data Applications

Nicely suitable for Delay tolerant applications

Our work also considers the feasibility of flow-based applications

Delay and Disruption Delay and Disruption Tolerant NetworksTolerant Networks

A large burst of recent activitiesSome commonality but also lots of

different approachesA coherent picture is beginning to

emerge

Epidemic Routing

Epidemic Routing

Epidemic Routing

Epidemic Routing

message isdelivered…

Vehicle-to-Vehicle Networks

SourceDestination

Vehicle-to-Vehicle Networks

SourceDestination

Vehicle-to-Vehicle Networks

SourceDestination

DakNet

Our Work

The Message Ferrying ParadigmThrowboxes to enhance capacityPower Management in DTNsVehicle-to-Vehicle NetworksPrototyping and Testbed Efforts

Message Ferrying (MF)Exploit non-randomness in device

movement to deliver data A set of nodes called ferries responsible

for carrying data for all nodes in the network

Store-carry-forward paradigm to accommodate disconnections

Ferries act as a moving communication infrastructure for the network

Message Ferrying

s

Message Ferrying

s

Message Ferrying

s

MF Variations

Ferry mobility Task-oriented, e.g., bus movement Messaging-oriented, e.g., robot movement

Regular node mobility Stationary Mobile: task-oriented or messaging-oriented

Number of ferries and level of coordination Level of regular node coordinationFerry designation

Switching roles as ferry or regular node

Questions Our Research Answers

How to route the ferryHow to manage multiple ferriesHow to insure fault tolerance

Throwboxes

Basic idea: add new devices to enhance data transfer capacity between nodes

Deploy throwboxes to relay data between mobile nodes

Throwboxes are: small, inexpensive, possibly dispensable,

battery-powered wireless devices Some processing and storage capability Easy to deploy and replenish

Example: DTN w/out Throwboxes

Example: DTN w/ Throwboxes

Our Work Considers

Placement of ThrowboxesThrowbox prototypes (UMass)

V2V Networks

Vehicle RelayingV3: Vehicle-to-Vehicle Video

Streaming

Prototyping Efforts

DTNrg Spec-Compliant implementation

Cisco Mobile RoutersDieselNet (UMass)

Concluding Remarks

Mobility-Assisted Data DeliveryFINALLY! A realistic mobile wireless

network paradigmEverything looks familiar but this is a truly

different environmentTechniques developed have wide

applicabilityFertile Ground for both networking

problems and novel application paradigms

Concluding Remarks

Mobility-Assisted Data DeliveryFINALLY! A realistic mobile wireless

network paradigmEverything looks familiar but this is a truly

different environmentTechniques developed have wide

applicabilityFertile Ground for both networking

problems and novel application paradigms