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Seaweb Acoustic Wide-Area Networks for Undersea Sensor Grids Joe Rice, Chris Fletcher, Bob Creber SPAWAR Systems Center, San Diego rice @ spawar.navy.mil (831) 656-2982 Dave Johnson, ONR 321 Littoral ASW FNC (DADS) Don Davison, ONR 321 Discovery (Telesonar) Larry Green, ONR 321 Discovery (Sealan) Jim Eckman, ONR 321 NOPP (FRONT) Doug Harry, ONR 36 (SBIRs) LCDR John King, NWDC (Sublink) Seaweb Communication & Navigation Seaweb CONCEPT OF OPERATIONS Extend networkcentric C4ISR into the undersea battlespace Use telesonar digital communications to form deployable autonomous distributed sensor networks with: Rice, “Telesonar signaling and seaweb • wide-area coverage underwater wireless networks,” Proc. NATO New Information Processing Techniques for • architectural flexibility Military Systems,” October 2000 • environmentally adaptive wireless links • self-configuring ad hoc topologies • fixed sensor nodes and repeater nodes • fixed and mobile peripheral nodes, e.g. bi-static projectors and UUVs • fixed and mobile gateway nodes linked to command centers submerged, afloat, aloft and ashore Space & Naval Warfare Systems Center, San Diego 2 Background: 2nd-generation telesonar modem was developed through a SPAWAR-sponsored SBIR phase-2 contract to Datasonics Seaweb ATM-885 3rd-generation telesonar modem was developed through an ONR-sponsored SBIR phase-3 contract to Datasonics (now Benthos) Recent Navy enhancements: Space & Naval Warfare Systems Center, San Diego TMS320C5410 DSP chip Improved low-power wake-up Moderate-power addressing Modularized type-A algorithms Utility packets Probe signals Seaweb protocols Partial-band modes Adaptive power control 3 Seaweb FBE India June 2001 Space & Naval Warfare Systems Center, San Diego 2 Racom gateway buoys 2 DADS sensors 10 telesonar repeaters USS Jefferson City equipped with sublink as a BSY-1 TEMPALT Ashore ASW command center GCCS-M links to fleet Flawless ops for entire 4-day test period 4 Telesonar undersea digital communications Seaweb PROBLEM: Littoral undersea environments impair signal propagation A RTS CTS DATA B ARQ DATA 9 bytes 9 bytes up to 2 kbytes 9 bytes up to 2 kbytes APPROACH: Low-data-rate, spread-spectrum, channel-tolerant, secure RTS utility packet initiates the telesonar link and uniquely addresses the intended receiver node Received processes RTS as a channel probe, permitting estimation of prevailing scattering function and identification of viable signaling options CTS utility packet fully specifies the format for ensuing DATA transmission DATA packet has optimal coding, modulation, bit-rate, and power PAYOFF: Channel-adaptive modulation enables undersea networks with Rice, et al, “Adaptive modulation for undersea security, reliability, efficiency, and low cost Space & Naval Warfare Systems Center, San Diego acoustic telemetry,” Sea Technology, May5 1999 Telesonar message example Space & Naval Warfare Systems Center, San Diego Seaweb 6 The seaweb server interfaces the undersea network and the client systems Seaweb Other Command Centers TCP / IP seaweb 1 seaweb N seaweb super server passive Seaweb servers “netTCP / IP centric” C4ISR Sensor Station 1 Sensor Station N Command Center Seaweb networks connect to manned command centers via radio, acoustic, wire, and fiber gateway links Space & Naval Warfare Systems Center, San Diego Fletcher, et al, “Undersea acoustic network operations through a database-oriented server/client interface,” Proc. IEEE Oceans, November 2001 7 Seaweb FBE-I seaweb service DADS - shore links (61 ASW contact reports) DADS - sub links (listen-all) Shore - sub links (cellular-like) Shore - DADS links Sub - shore link (122 messages) Sub - DADS link Shore - repeater links Sub - repeater links Approx 793 MAC-layer transmissions (up to 3700 m) 135 ARQ-prompted retries Space & Naval Warfare Systems Center, San Diego 8 Seaweb FBE-I Seaweb service Space & Naval Warfare Systems Center, San Diego DADS - shore links (61 ASW contact reports) Sub - shore links (122 messages) Approx 793 transmissions 135 ARQ-prompted retries 121 one retransmission 5 two retransmissions 9 three retransmissions 2253 total RTS 1753 total CTS Creber, et al, “Performance of undersea acoustic networking using RTS/CTS handshaking and ARQ transmissions,” Proc. IEEE Oceans, November 2001 9 Seaweb FBE-I Seaweb service DADS - shore links (61 ASW contact reports) Sub - shore links (122 messages) Approx 793 transmissions 135 ARQ-prompted retries Number of Message Hops 83.0% 600 400 15.3% 200 0.6% 0 0 1 2 1.1% 3 Number of ARQs per Message Hop Space & Naval Warfare Systems Center, San Diego 121 one retransmission 5 two retransmissions 9 three retransmissions 2253 total RTS 1753 total CTS Creber, et al, “Performance of undersea acoustic networking using RTS/CTS handshaking and ARQ transmissions,” Proc. IEEE Oceans, November 2001 10 Throughput Seaweb DADS Report Position Report Comex/FINEX Comb Pos Report Opnote Chat Ovly ATI.ATR DADS Report Total Position Report FBE-I June 20-23 Bandwidth Analysis for 20- Message # Analysis for 20-23 June 14000 Comb Pos Report Opnote Opnote 20 Comex/FINEX 6/2 1/2 001 6/2 2/2 001 6/2 3/2 001 DADS Report Space & Naval Warfare Systems Center, San Diego ATI.ATR 6000 Total Total ATI.ATR Ovly Chat Opnote Comb Pos Report Mess Comex/FINEX Position Report DADS Report 4000 2000 Message 0 Types 6/23/2001 Ovly 8000 6/22/2001 Total 40 Ovly 6/21/2001 6/23/2001 Chat 10000 Bytes of Data 6/2 0/2 001 Comex/FINEX Types 12000 60 0 16000 6/20/2001 of ages 80 6/22/2001 100 # of messages 6/21/2001 6/20/2001 120 # of bytes Total ATI.ATR Ovly Chat Opnote Comb Pos Report Message Comex/FINEX Position Report DADS Report 11 Seaweb Packet latency Latency (minutes) Submarine to ASWCC, FBE-I June 22 10 Nominal latency about 1 minute 9 Small deviations caused by network route variations 8 Large latencies caused by network interference or poor channel forcing the automatic use of handshake retries and/or ARQs 7 6 5 4 Dropped packets caused by inappropriate cellular addressing by submarine 3 2 1 0 Packet number Space & Naval Warfare Systems Center, San Diego Rice, et al, “Networked undersea acoustic communications involving a submerged submarine, deployable autonomous distributed sensors, and a radio gateway buoy linked to an ashore command center,” Proc. UDT Hawaii, October 2001 12 FRONT ocean observatory Seaweb FRONT-3, March-June, 2001 Space & Naval Warfare Systems Center, San Diego 13 Seaweb 2001 included the Hydra off-board sensor against USS Dolphin Seaweb 9-week experiment culminating in the annual Seaweb 2001 firmware CDPD modems used extensively for gateway comms Network header introduced for machine-to-machine networked communications ARQ formalized as a separate dialog RCPT and ACK utility packets implemented Space & Naval Warfare Systems Center, San Diego 14 Iceweb 2002, April 2002 Seaweb US participation in international ICESHELF 2002 experiment Ice-mounted seaweb network First test of acoustic networking in the Arctic Ocean First integration of Canadian UCARA sensor as a seaweb node Prepares for RDS-4 experiment with interoperable US and Canadian ASW sensor nodes Space & Naval Warfare Systems Center, San Diego 15 Portable undersea comm/nav ranges Seaweb teaming with NUWC Keyport Ping/Echo utility packet dialogs Broadcast ping produces staggered echoes from all receivers Mobile node can track own position, and range can track mobile node FBE-I demonstrated the fundamentals of this seaweb application Space & Naval Warfare Systems Center, San Diego 16 Mobile Gateway Seaweb Slocum UUV Glider Webb Research Corporation SBIR Phase II awarded to produce mobile gateway communication models: Replace acoustic tracking system with telesonar modem Move acoustic transducer to nose area Incorporate mobile gateway missions into operating profile Reserve buoyancy increase to allow better antenna height New antenna designs for LOS and L-Band SATCOM radios New nose cone, with new modem and altimeter transducers Slocum Low-power Mobile Ocean Profiler sponsored by ONR 322OM – – – – – Space & Naval Warfare Systems Center, San Diego Buoyancy driven CTD sensor GPS receiver and data radio Antennas located on tail fin Designed especially for shallow water—can operate in less than 10 feet of water 17 APL/UW Seaglider and Webb Research SLOCUM glider serve as mobile autonomous gateway/master nodes Space & Naval Warfare Systems Center, San Diego Seaweb 18 Seaweb Summary Seaweb is a wide-area network for sensor grids Fixed: DADS, Hydra, Kelp, UCARA, FRONT, Wetnet Mobile: SLOCUM, ARIES, EMATT Moored: Racom, Freewave, CDPD, Satcom options Sealan is a local-area network for sensor clusters Centralized networks with asymmetric links DARWIN, oceanographic moorings, sensor uploads to servicing UUVs, dive teams, MCM swarms Central nodes are Seaweb-compatible Sublink permits submarine access USS Dolphin, Sublinks ’98, ’99, 2000 USS Jefferson City, Sublink 2001, FBE-I Space & Naval Warfare Systems Center, San Diego 19 Seaweb Back-up slides Space & Naval Warfare Systems Center, San Diego 20 Seaweb 2-node MAC-layer state diagram Node A idle idle Node B Wake up Xmt RTS Rcv RTS Time out Xmt CTS Rcv CTS RTS Xmt DATA Time out or ARQ Rcv DATA Xmt ACK/ARQ Rcv ACK/ARQ idle Space & Naval Warfare Systems Center, San Diego ARQ ACK idle 21 FBE-I acoustic propagation Ray-trace diagram for a bottom source and typical sound speed profile for the region. Ray launch angles extend from 0 to 20 at 0.5 increments. Bottom reflected paths are omitted for clarity. Baxley, et al, “Shallow-water acoustic communications channel modeling using three-dimensional Gaussian beams,” Proc. MTS Ocean Community Conf., November 1998 Space & Naval Warfare Systems Center, San Diego Seaweb Sound speed profiles obtained from CTD measurements before and after the experiment. Simulated impulse responses for a bottom-deployed source and receiver for five source ranges from 1 to 5 km at 1-km increments. 22 Seaweb Sealan operates with situationally adaptive multi-access modes Polled TDMA Token TDMA Other multi-access modes: Scheduled TDMA Asynchronous TDMA CDMA/FDMA Clandestine modes Hybrid modes Handshaking modes Full-duplex modes Space & Naval Warfare Systems Center, San Diego 23 The telesonar network organizes and maintains itself under the control of autonomous master nodes or seaweb servers at command centers Preparation 10 days Installation 1 day Activation 1 hr Analyze mission requirements Measure or predict environment Model transmission channels Predict connectivity range limits Specify spacing, aperture, and node mix Pre-program master node only Obey spacing constraints Test master node link to gateway Awaken network nodes Discover neighbors Initiation 2 hrs Obtain reciprocal channel response Perform 2-way ranging Sound own depth Initialize spectral shaping Registration 1 hr Report link data & node configuration Assimilate data at master node Optimization 1 hr Compute optimal/alternate routes Assign protocols Operation 90 days Monitor energy, links, and gateways Optimize life, covertness, and latency Space & Naval Warfare Systems Center, San Diego Seaweb 24 Seaweb 2002-2003 experiments Seaweb FRONT-4, US Eastern seaboard Signalex, San Diego Bay HF Signalex, San Diego Bay Iceweb 2002, Arctic Ocean Wetnet 2002, San Diego Bay Seaweb 2002, Buzzards Bay DADS-D, San Diego Bay RDS-4, Halifax, Canada DADS-D, San Diego Loma Shelf Asymmetric links, Monterey Bay Jan-June 2002 April 2002 April 2002 April 2002 May 2002 July-Aug 2002 September 2002 Sept-Oct 2002 November 2002 July-Dec 2002 FBE-K Singapore Summer 2003 Fall 2003 Space & Naval Warfare Systems Center, San Diego 25