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An Experimental Mobile Ad Hoc Networking Testbed

Kick-off meeting for an experimental project on mobile network connections via hotspot, 3G coverage, and ad hoc relaying. Objectives include exchanging emergency/traffic information, implementing peer-to-peer networking, and evaluating ad hoc protocols for telematics applications.

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An Experimental Mobile Ad Hoc Networking Testbed

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  1. An Experimental Mobile Ad Hoc Networking Testbed Project Kick-off Meeting March 1, 2004

  2. Mobile Network Connections Connect via Hotspot Internet Hot spot coverage Car range Connect via 3G Ad hoc relaying 3G coverage

  3. Peer-to-Peer Networking • Exchange of emergency/traffic information • Exchange of diagnostic information • Active safety applications • Allow one vehicle to function as a network portal for nearby vehicles • Vehicle as sensor

  4. IETF Draft Protocols • On Demand Protocols • Pro: minimize network overhead since routes are refreshed only when needed • Con: excess latency when invoking seldom-used routes • IETF Drafts: • Dynamic Source Routing (DSR) • Ad Hoc On Demand Distance Vector Routing (AODV) • Proactive Protocols • Pro: minimize latency since routes are fresh • Con: excess network overhead to update routes even if not used • IETF Drafts: • Optimized Link State Routing Protocol (OLSRP) • Topology Dissemination Based on Reversed-Path Forwarding (TBRPF)

  5. Specific Requirements for Telematics Applications • Epidemic Flood-Fill protocols with hop limits • Perhaps more appropriate than protocols used with specific destinations in mind • May not want to propagate to near-by but distinct roads/highways (e.g., highway crossings without interconnects, etc.) • Proprietary Solutions • MeshNetworks? • Implementations of IETF protocols are almost all in UNIX (BSD, Linux, etc.)

  6. Proposed Ad Hoc Testbed 1XRTT GPS DGPS reference station beacons MN V Internet Site Office Network can operate wherever DGPS beacons and 1XRTT are available

  7. Network Components • Mobile Node • 5.8 GHz 802.11a (Represents DSRC) • 1XRTT Cellular/PCS 3G data • Ad Hoc Protocol (DSR?) • Differential GPS • Site Office • Bird’s eye view of test track (tests not limited to track, however) • Visualizer & Analysis tools

  8. Vizualizer Example

  9. Video

  10. Example Measured & Modeled Signal Strength Time (s) (Data from Prior Ad Hoc Network supported by Caterpillar)

  11. Example Dropped Packet Performance (Data from Prior Ad Hoc Network supported by Caterpillar)

  12. Research Objectives: Physical & Link Layers • Collect extensive peer-to-peer channel RSSI data and extract path loss exponents for classes of environments (e.g., Urban, suburban, rural, etc.). • Investigate the expected range, reliability, throughput of 802.11a/DSRC in this mobile environment • Implement the capability of real-time power control for sparse/dense traffic, and evaluate performance • Management of channels, e.g., control & data • Collaborate with HRL to integrate findings with their simulations

  13. Improved Channel Measurement Options:Sliding Correlator Method • N=code sequence length • Rc=transmit chip rate • Rc-d = receive chip rate • Time resolution ~1/Rc • E.g., Rc=12.5 Mbps, gives resolution ~ 80 ns • Gives measurement of RMS delay spread Devasirvatham ‘86

  14. Sliding Correlator Implementation Possibilities BPSK + CW pilot • Without pilot locking: phase drift is 90 deg/s • Should also permit analysis of Doppler

  15. Multi-carrier Probing MCM

  16. Research Objectives: Network & Higher Layers • Evaluate the performance of leading ad hoc protocols for the automotive/ITS application environment • Develop suite of protocols for active safety/telematics applications • Define latency requirements • Explore multi-hop relaying, and attempt to determine the limiting factors to the range (i.e., number of hops) • Identify and implement “hooks” throughout the stack that will facilitate delivery of the required QoS • Collaborate with HRL to integrate findings with their simulations

  17. GM Contributions • Application concepts • Antenna and mounting issues • System and vehicle integration architecture • Standards activities • Vehicles

  18. Phase I Tasks Q1-04 Q2-04 Q3-04 Q4-04 Q1-05 Q2-05 Q3-05 Q4-05 1. Construction a. Site selection b.Protocol select c. Vehicle acq. d. MN integ. e. MN install f. SO integ. g. SO install h. Visualizer i. System integ. 2. Layer 1,2 Res. a. Chan. Model b. Ch. Mod. Opt c. 802.11a perf. d. Power control 3. Layer 3-6 Res. a.Platform select b. Protocol Eval c. Protocol Suite d. Latency Req. e. Hop limits f. Hooks in stack 4. MANET stds 5. HRL collab. Timeline

  19. Summary • Ad hoc network using 5-6 vehicles to be constructed • Network capable of operation anywhere DGPS beacons are available (also 1XRTT for site office connectivity) • Develop 5-6 GHz peer-peer propagation model • Develop suite of protocols optimized for telematics/active safety applications • Collect real data on network operation to use in validating simulations • Timeline: construct in ~ 9 mo; operate for 15+ mo

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