Seaweb SPAWAR Systems Center, San Diego 1 Joseph A. Rice SPAWAR Systems Center, San Diego Naval...
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Transcript of Seaweb SPAWAR Systems Center, San Diego 1 Joseph A. Rice SPAWAR Systems Center, San Diego Naval...
SPAWAR Systems Center, San Diego 1
Seaweb
Joseph A. Rice
SPAWAR Systems Center, San DiegoNaval Postgraduate School, Monterey
+1 831 402 [email protected]
Seaweb is a US Navy experimental technology.
DARPA ATO Disruption Tolerant Networking ProgramAugust 2, 2005
Seaweb acoustic com/nav networks
SPAWAR Systems Center, San Diego 2
SeawebUS Navy Seaweb InitiativeEnabling Undersea FORCEnet for cross-system, cross-platform, cross-mission, cross-nation interoperability
Through-water digital com/nav networksScaleable wide-area wireless gridComposeable architectural flexibilityFixed and mobile autonomous nodesGateways to command centersPersistent and pervasiveLow source level, wide band, high freq
Integrated undersea applicationsLittoral ASW sensor telemetryMETOC sensor telemetrySensor-to-sensor cueingSubmarinesSubmersiblesUUVsCollaborative operationsCommand & controlDeployable rangesHarbor defense
J. Rice, “Enabling Undersea FORCEnet with Seaweb Acoustic Networks,” Biennial Review 2003, SSC San Diego TD 3155, pp. 174-180, December 2003
SPAWAR Systems Center, San Diego 3
Seaweb
Experimental DADS sensor node
Demonstrated capabilities:
FBE-India June 2001
J. 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
SSN with BSY-1 sonar Seaweb TEMPALT
Ashore ASW command center
Seaweb server at SSN and ASWCC
Acoustic chat and GCCS-M links to fleet
SSN/MPA cooperative ASW against XSSK
Flawless ops for 4 continuous test days
Racom buoy
SPAWAR Systems Center, San Diego 4
SeawebSeaweb message example:
Multi-Access Collision Avoidance (MACA) Internet Protocol (IP)
RT
SCTS
DA
TA
RTS
RT
S
RTS
CTS
CT
S
CTS
DATA
DA
TA
DATA
G. Hartfield, Performance of an Undersea Acoustic Network during Fleet Battle Experiment India, MS Thesis, Naval Postgraduate School, Monterey, CA, June, 2003
SPAWAR Systems Center, San Diego 5
SeawebUS Navy SPAWAR SBIR topic N93-170 advanced and commercialized DSP-based acoustic comms
SBIR contractor: Benthos, Inc. (formerly Datasonics, Inc.)
3rd generation telesonar modem, Benthos ATM-885• Introduced in 2000• TMS320C5410 DSP• 5-kHz bandwidth• 2400 bit/s, uncoded• 15 kbit/s with optional daughter board • Various forward-error-correction options
4th generation telesonar in development, SBIR N03-224
Standard firmware for non-networked applications• UUV command & control• Oceanographic telemetry• Tsunami warning systems• Oil industry
US Navy firmware for Seaweb applications
ATM-885 telesonar modem
K. Scussel, “Acoustic Modems for Underwater Communications,” Wiley Encyclopedia of Telecommunications, Vol. 1, pp. 15-22, Wiley-Interscience, 2003
SPAWAR Systems Center, San Diego 6
SeawebPlanned approach:
Adaptive modulation
Reconstruct transmitted waveform
Estimate channel scattering function
Map channel characteristics against available repertoires
and signal techniques
Final decision
RTS
Data
CTS
Node BNode ADemodulate
RTStransmission
SpecifyData-packet
commsparameters
Determine h(τ, t ) / Doppler / SNR
S. Dessalermos, Undersea Acoustic Propagation Channel Estimation, MS Thesis, Naval Postgraduate School, Monterey, CA, June 2005
SPAWAR Systems Center, San Diego 7
SeawebDemonstrated capability:
MACA (multi-access collision-avoidance) protocol enables undersea networks with security, reliability, efficiency, and low cost
J. Rice, et al, “Adaptive Modulation for Undersea Acoustic Telemetry,” Sea Technology, May 1999
A BRTSRTS 9 bytes
CTSCTS 9 bytes
DATADATA up to 2 kbytes
SRQSRQ 9 bytes
DATADATA up to 2 kbytes
Seaweb channel-tolerant utility packets resolve the compound constraints of:Variable QoS, link outagesChannel multipath, Doppler, dynamic SNR Limited spectral bandwidth Asymmetric, half-duplex channelSlow propagation, long latenciesMulti-access interferenceBattery-limited operations
SPAWAR Systems Center, San Diego 8
SeawebSeaweb 2005 NSW ExperimentFebruary 2005, Panama City, FL
SRQ link-layer mechanismNSMA (Neighbor Sense Multiple Access, a cross-layer variation on CSMA)Ranging and node localizationNew repeater mooring designIridium-equipped Racom buoySDV Periscope ControllerCompressed image telemetry NPS, SSCSD, CSS, Benthos
DADS ASW BarrierSea Eagle ACTD NSW Expeditionary Ops2010 Mine RECO
SPAWAR Systems Center, San Diego 9
SeawebDemonstrated capability:Selective Automatic Repeat Request (SRQ) is a link-layer mechanism for reliable transport of large datafiles even when the physical layer suffers high BERs
Node A Node BRTS
CTS
HDR
SRQ
HDR
SRQ
HDR
3. Node A transmits a 4000-byte Data packet
using 16 256-byte subpackets, each with an independent CRC.
4. Node B receives 12 subpackets successfully; 4 subpackets contained uncorrectable bit errors.
5. Node B issues an SRQ utility packet, including a 16-bit mask specifying the 4 subpackets to be retransmitted.
6. Node A retransmits the 4 subpackets
specified by the SRQ mask.
7. Node B receives 3 of the 4 packets successfully (future implementation of cross-layer time-diversity processing will recover 4 of 4). B issues an SRQ for the remaining subpacket.
8. Node A retransmits the 1 subpacket
specified by the SRQ.
2. Node B is prepared to receive a large Data packet as a result of Seaweb RTS/CTS handshaking.
1. Node A initiates a link-layer dialog with
Node B.
9. Node B successfully receives and processes Data packet.
J. Kalscheuer, A Selective Automatic Repeat Request Protocol for Undersea Acoustic Links, MS Thesis, Naval Postgraduate School, June 2004
SPAWAR Systems Center, San Diego 10
SeawebDemonstrated capabilities:
Seaweb 2004 UV racom buoy
Deck Staging 6-8 min deployment time
SPAWAR Systems Center, San Diego 11
SeawebSeaweb 2004 Undersea Vehicle Experimentcellular grid deployment
Average speed 6.5 knotsAverage 1 repeater every 20 min
SPAWAR Systems Center, San Diego 12
Seaweb
SPAWAR Systems Center, San Diego 13
SeawebSeaweb 2004 grid post mortemImpacted by trawling along the 300-m isobath3 nodes removed, 6 nodes displaced or damaged
COMEX FINEX
SPAWAR Systems Center, San Diego 14
Seaweb
104 11161 56 56
264
0
50
100
150
200
250
300
UnderseaVehicle
transmissions
Ship receptions Shiptransmissions
UnderseaVehicle
receptions
UnderseaVehiclereturnedreceipts
Ship receivedreceipts
Seaweb 2004 ExperimentUndersea Vehicle initiates the Seaweb sessions
Initiating message
Response message
Return receipt
Seaweb network-layer success
Undersea Vehicle
Ship
Undersea Vehicle
Seaweb network-layer statistics show excellent performance with dropped messages attributable to UV limited aspect, UV fix-expansion uncertainty, and interference from other UV active sonar
Ship
SPAWAR Systems Center, San Diego 15
SeawebThe Seaweb Initiative is performing Seaweb navigation experiments this year as risk mitigation for CNAV
Seaweb 2005 UUV ExperimentsMonterey Bay, May 9-11, July 20-22St. Andrews Bay, December 5-9
constellation of 6 Seaweb repeater nodes
fixed on seabed
SLOCUMUUV
Shipboardcommand center
Racom buoy gateway node
Iridium satellite constellation
ARIES UUV
GPS satelliteconstellation
NPS
SPAWAR Systems Center, San Diego 16
SeawebDARPA CNAV architectures include situation adaptive, energy conserving, and transitional topologies
• Mobile formations• Swarms• Mobile node as
gateway• Zebranet flooding
• Assimilation following ad hoc deployment
• Fixed grids• Self-healing• Seamule
SPAWAR Systems Center, San Diego 17
SeawebWhat can DTN do for Seaweb?
Network layer is fragile – needs dynamic routing for healing during/after disruption
No reliable packet transport
need mechanism for recovering lost packets at the network layer
No support for data mules
Infrastructure support needs work
currently no packet counter (move to 8b)
rough time synchronization: ~0.1s resolution, 16b timer, ~12 hour rollover
Seaweb expertise is UW acoustics & systems, not in networking
Simulation support lacking (OPNET radio modeler has been adapted for the telesonar channel)
Development funding & assistance from network experts
SPAWAR Systems Center, San Diego 18
SeawebWhat does Seaweb do for D-DTN?(why get involved?)
General:
Closely related to tactical radio MANET problem
Naval warfare applications/transition
Specific:
Reality check for DTN in harsh environments
“brutal constraints” comparable to MANPACK constraints
DTN isn’t a bolt-on – need a stripped-down bundle protocol
issues with time stamps, header efficiency, time sync
DTN must be integrated into system with routing etc
DTN gets a hard problem with a likely transition on success
Can DTN be made to work in such constrained environments?
Testbed
system to sea roughly 4 times a year
SPAWAR Systems Center, San Diego 19
Seaweb
Seaweb advanced conceptsSaturating the undersea battlespace
Backward compatible with Seaweb
Seastar tier
Sensor grids and UUV swarms against SSK, UUV, and sea-mine threats
Networked weaponry
Fully mobile networks (e.g., CNAV)
Seastar local-area
network
SubmarineSubmarineLow-rate
C2
Autonomous Autonomous nodenode
High-ratedata telemetry
Asymmetric links
Seamules
Seaweb wide-area network
¼ A-size modem
Conclusion:
Seaweb is an enabling technology for Undersea FORCEnet and Sea Shield
Seaweb spiral developmentFulfilling the Seaweb blueprint
Directional transmit & receive
Four bands
Full physical-layer repertoire, from low-rate/clandestine to high-rate/overt signaling
Adaptive modulation & power control
Automatic cellular handoff for mobile nodes
Ad hoc network initialization
Integration with manned platforms