ALeRT Project Georgia Tech and UMass Amherst DARPA DTN Meeting 2 August 2005 Washington, DC.

ALeRT Project

Georgia Tech and UMass AmherstDARPA DTN Meeting

2 August 2005Washington, DC

DARPA DTN August Meeting

Overview: DTN Design

1. Reliable delivery – enhancement of basic routing for increased reliability

2. Network design – design and evaluation of novel devices (ferries and throwboxes) to enhance DTN performance

DARPA DTN August Meeting

Project Goal: Reliability

• Design and evaluate intelligent bundle discard policies

• Design an efficient drive-by transfer (DBT) protocol and efficient link layer system design

• Demonstrate high performance drive-by transfer

DARPA DTN August Meeting

Bundle Discard Policies

Testbed30 bus vehicular DTN network

Each bus: Linux “brick” computer; USB 802.11b adapter; 802.11b AP; GPS receiver, 40GB hard drive

Buses route messages as they pass by each other and via available hot spots

Traces collected everyday

Bundle Discard Sort packets for transmission opportunities

based on likelihood of eventual delivery; delete in reverse order

Network-wide ACKs clear buffers

Priority given to new packets over old

Evaluations based on traces of real bus movement, 802.11/TCP transfers

Performs better than a Dijkstra-based protocol with a meeting oracle

DARPA DTN August Meeting

Link Layer System Design

SolutionTwo Bluetooth radios on one

device provides a duplex channel.

SR = single radio; DR = dual radio

ProblemDTN nodes must find each other,

connect, and send data.

Most widely-deployed wireless technology – Bluetooth - thwarts neighbor discovery, since radios cannot be found while searching for others.

EvaluationSR = single radio; DR = dual radioCurrently evaluating performance

of 802.15.4 and 802.11

Comparing energy efficiency and achievable transfer rates of both.

DR allows much faster node speeds higher achievable rates

DARPA DTN August Meeting

Project Goal: Network Design

• Design and evaluate message ferries in a DTN environment to improve performance metrics

• Design and evaluate schemes for improving the reliability of DTNs that use message ferrying capability

• Investigate the potential for power savings through the use of message ferries in DTNs

• Develop strategies for deploying throw-boxes to enhance DTN performance

DARPA DTN August Meeting

Network Design: Message Ferries

ObjectiveImprove DTN performance by intelligent network design. Develop new components --- ferries and throw-boxes. Design the network via control over initial component placement, component mobility, and power consumption.

ImpactOrder of magnitude improvement using MF forwarding (MFv) versus epidemic routing (ER), when movement is area-based. MURA = ferries with multiple routes; more ferries directly increases capacity and decreases delay

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MURA, m=2MURA, m=4MURA, m=8

MURA, m=16

DARPA DTN August Meeting

Component Design: Throwboxes

SolutionHeterogenous embedded systems:

Stargate: 300-1000mW, TelosB: 10s of mW

Combined in a single DTN throwboxShare battery power and solar chargingIntelligently switch between modules/radios

for bundle transfers and exchange of routing data

PrototypeStargate Xscale processor plus low-power

Atmel processorWiFi (802.11) and Zigbee(802.15)Cheap (<$1k), built with COTS, can be

made rugged for battlefieldImproves lifetime/availability by more than

order of magnitude over Stargate

Solar Cells

Stargate w/Wifi

TelosB w/802.15.4

Batteries

Durable Case

Problem

DTN nodes need “throw and forget” capability

inexpensive, long-lived

DARPA DTN August Meeting

Programmatics: Spending

• 37% expended at end of July 2005• 5 months into 14 month contract

• Spending is on track

DARPA DTN August Meeting

Programmatics: Schedule

Activity Months 1-6 Months 7-12

Months 13-14

Reliable delivery

• discard policies

• drive-by transfer

• demonstration

Network design

• message ferries

• MF reliability

• MF power control

• throw-boxes

DARPA DTN August Meeting

Go/No-Go Metrics

• DTN Testbed– Integrated bundle discard, message ferry

routing, Throwboxes

• Throwbox Platform– Completion of first prototype – Order of magnitude increase in lifetime over

Stargate alone

• Network Design– Order of magnitude increase in performance

over unplanned and uncontrolled networks

DARPA DTN August Meeting

Questions?