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DARPA Spectrum Challenge - The Basics 2 1.Adversarial communications (competitive tournament) Each team gets two radios (a Tx and an Rx) Two teams (four radios) will be competing at once Team that successfully transmits and receives give data file the fastest wins 2.Non-adversarial Spectrum Sharing (cooperative tournament) Four teams operate at once Multiple rounds are played in round robin format Teams score for round is the groups score Team with highest sum score after 10 rounds wins Each tournament will be competed twice: Prelim competition and Final competition Timeline Orbit Testbed 31 Jan: Register Team Feb: Complete Qualification Hurdles Mar: Contestants announced Sep: Preliminary Tournament Mar 2014: Final Tournament

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Competitive Setup SDDS DARPA Packet Server 3

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Cooperative Setup SD SD DARPA Packet Server SD 4

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Cognitive Spectrum Operations Testbed (CSOT) Ad-hoc DSC team formed from individuals at GTRI with an interest in SDRs Team background Leader: Bob Baxley Comms theory Ethan Trewhitt Machine learning, SW Andy Henshaw Tactical data links, SW Sean Nowlan Comms, Security, GNURadio Jeff Hodges Comms, SDR (Ettus/DRT/X-Midas) Brett Walkenhorst Comms theory Ryan Westafer Propagation physics Chris Valenta RFID, GNURadio/Ettus SDRs DSC & GTRI research Cognitive radio/sensing/EW SDR development Communication theory Team Information

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Development Logistics gr-GTRI GNURadio Module 1,842 Unique Files 6,405 Commits Most-Changed Files 1: grc/tx_ofdm_diff.grc 2: grc/Makefile 3: grc/rx_wreck.grc 4: gr-GTRI/python/GTRI_wirehair_enc.py 5: gr-GTRI/grc/CMakeLists.txt 6: grc/tx.grc 7: grc/gtri_tx.py 8: grc/rx_wreck_sense.grc 9: gr-GTRI/lib/tx_wreckC_impl.cc 10: grc/tx_inner.grc veriton-1 10.50.17.150 veriton-3 10.50.17.235 veriton-2 10.50.17.241 veriton-4 10.50.17.249 aspire-4 10.50.17.107 aspire-3 10.50.17.106 aspire-2 10.50.17.??? aspire-1 10.50.17.??? GTRI Router Lab Router USRP N210 SBX USRP N200 SBX USRP N210 SBX USRP N200 SBX USRP B210 GTRI SDRL Testbed Grid Workflow: dsc-code_tx/rx tmux gtri_tx/rx.py Start match: omf exec ssh grid ssh nodex-y tmux attach console output Kill match: tmux kill-session

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Common Waveform Elements Ns NNNN One Burst = One or more Packets (1452 raw bytes/packet) Preamble Symbol Sense Window 255 RS symbols K symbols One Raw Packet K= {121,132,162,182,20 8,242} File Server Packet 1440 Bytes WH 8 bytes CR C One Coded Packet {6,7,8,9,11,12} RS blocks/packet Start with the uncoded vector of packets: = = Rx a subset of the Tx rows 4: Wirehair erasure code If A is invertible, solve for x; if not, collect more symbols and try again: Transmit that vector and then create linear combination of x and transmit those too: (Do this forever) 1: Signal Structure 2: Synchronization Correlation over time One Burst Ns+s 3: Sensing Tx receives transmissions and correlates to find the sense window. This is 600 zero samples immediately after the preamble

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Tournament Radios: GTRI Wreck Waveform COOP (mostly-open loop): Ramblin 64-carrier OFDM;54 occupied carriers Data is differentially encoded across OFDM symbols; Each stream is an independent packet 54 parallel decoders at Rx Average 22 FFTs during sense window to estimate occupancy Carriers are dynamically nulled based on threshold; retransmit nulled Symbol-wise scaling to maximize SNDR 20s max speed; game rate is 33s Fast time: GR blocks at sample rate ( custom and canned blocks ) Slow time (20Hz): asynchronous function probes for adaptation ( all custom) COMP (closed loop): Wreck

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Competitive Mode: Second Place! Our waveform adapted well, becoming more aggressive when possible, falling back to robust when jammed Effectively jammed many competitors by using entire band Cooperative Mode: Effectively transmitted without colliding with other teams Retransmitted dropped packets Only team to complete our file in all matches Eliminated in first round due primarily to quirks in opposing teams approaches Competition Results

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Backup: Logo Screenshot