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

2. 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

3. 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

4. DARPA DTN August Meeting Bundle Discard Policies Testbed 30 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

5. DARPA DTN August Meeting Link Layer System Design Solution Two Bluetooth radios on one device provides a duplex channel. SR = single radio; DR = dual radio Problem DTN 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. Evaluation SR = single radio; DR = dual radio Currently 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

6. 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

7. DARPA DTN August Meeting Network Design: Message Ferries Objective Improve 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. Impact Order 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

8. DARPA DTN August Meeting Component Design: Throwboxes Solution Heterogenous embedded systems: Stargate: 300-1000mW, TelosB: 10s of mW Combined in a single DTN throwbox Share battery power and solar charging Intelligently switch between modules/radios for bundle transfers and exchange of routing data Prototype Stargate Xscale processor plus low-power Atmel processor WiFi (802.11) and Zigbee(802.15) Cheap (<$1k), built with COTS, can be made rugged for battlefield Improves 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

9. DARPA DTN August Meeting Programmatics: Spending 37% expended at end of July 2005 5 months into 14 month contract Spending is on track

10. DARPA DTN August Meeting Programmatics: Schedule Activity Months 1-6Months 7-12Months 13-14 Reliable delivery discard policies drive-by transfer demonstration Network design message ferries MF reliability MF power control throw-boxes

11. 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

12. DARPA DTN August Meeting Questions?