Seaweb SPAWAR Systems Center, San Diego 1 Joseph A. Rice SPAWAR Systems Center, San Diego Naval Postgraduate School, Monterey +1 831 402 5666 [email protected]

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


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


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


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


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


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


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


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


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


SeawebDemonstrated capabilities:

Seaweb 2004 UV racom buoy

Deck Staging 6-8 min deployment time


SeawebSeaweb 2004 Undersea Vehicle Experimentcellular grid deployment

Average speed 6.5 knotsAverage 1 repeater every 20 min


Seaweb


SeawebSeaweb 2004 grid post mortemImpacted by trawling along the 300-m isobath3 nodes removed, 6 nodes displaced or damaged

COMEX FINEX


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


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


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


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


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


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

Documents

Seaweb SPAWAR Systems Center, San Diego 1 Joseph A. Rice SPAWAR Systems Center, San Diego Naval Postgraduate School, Monterey +1 831 402 5666 [email protected]