US Navy Seaweb program Undersea acoustic sensing, signaling, communications

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US Navy Seaweb program Undersea acoustic
sensing, signaling, communications networks

• Networked through-water digital com/nav
• Scalable wide-area wireless grid
• Composable architectural flexibility
• Fixed and mobile autonomous nodes
• Gateways to command centers
• Persistent and pervasive
• Low source level, wide band, high freq
• TRANSEC attributes
• Integrating sensors, UUVs, SSNs

• Sponsors ONR, PEO LMW, SOCOM PEO IIS, CTTSO, PEO
  C4I Space, PEO IWS, OSD, DARPA, SBIR
• Collaborations
• TTCP Unet (Undersea networking)
• DARPA DTN (Disruption-Tolerant Networking)
• ONR DADS (Deployable Autonomous Distributed Sys)
• ONR ASAP (Adaptive Sampling Prediction)
• OSD Coalition Warfare
• Seaweb is in routine use by several client
  programs
• POC Joe.Rice_at_navy.mil, [phone]

J. Rice, Enabling Undersea FORCEnet with Seaweb
Acoustic Networks, Biennial Review 2003, SSC San
Diego TD 3155, pp. 174-180, Dec 2003
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US Navy Seaweb programApplied research,
Discovery Invention, 6.2 fundingArt of the
possible for Maritime sensor networks Undersea
Distributed Networked Systems (UDNS)
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SPAWAR SBIR topic N93-170 advanced and
commercialized DSP-based acoustic comms SBIR
contractor Teledyne Benthos (formerly
Datasonics, Inc.)
Pre-SBIR ATM-845 ATM-865
SBIR Phase-2 ATM-875
SBIR Phase-3 ATM-885

• 2000-2007
• TMS320C5410
• 3rd generation telesonar
• Spiral development

• 1993-97
• all analog
• 10 b/s FSK

• 1997-99
• TMS320C50
• 2nd generation telesonar
• Spiral development

SBIR Phase-1 ATM-850 (not shown)

• 1997-2003 achievement
• Stable COTS hardware
• COTS Navy firmware
• 8X less expensive
• 40X more efficient

• 1995-97
• Multi-band MFSK
• 1st generation telesonar
• Technology transfer from MIT/WHOI

2007 4th gen telesonar with TRANSEC features
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TBEDNavys first experimental digital sensor
network1995-96

• TBED Telemetry Buoy Environmental Data
• NSWC Coastal Systems Station, Panama City, FL
• Objective telemeter environmental data from
  distributed seafloor sensor nodes to one or more
  gateway nodes
• Sea test in 1996
• Gulf of Mexico, 60 km offshore Panama City, 45-m
  water
• 8-km node-to-node ranges achieved
• 4 Datasonics ATM-850 telesonar modems
• 150-bit/s, 1024-bit messages
• Flooding protocol designed for up to 10 nodes
• Advantages Simple, COTS modem firmware, Plug
  play, Routing tables not required, Centralized
  control not required
• Disadvantages Redundant communications, Not
  bandwidth efficient for fixed network, High
  latency
• Analogous to terrestrial Zebranet
• Well suited for delay-tolerant AUV mobile networks

J. Rice, et al, Evolution of Seaweb Underwater
Acoustic Networking Proc IEEE Oceans 2000
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Seaweb 98 engineering experimentBuzzards Bay,
MA, September 1999An undersea wireless sensor
network employing ten telesonar modems and an RF
gateway buoy
4143
10-m water depths 10 ATM-875 telesonar
modems 3-FDMA 3 sensor nodes FreeWave
gateway Bi-directional routing tables Scaleable
architecture
ATM-875
Isobath contours at 5-meter intervals
4135
7046
7036
M. D. Green, J. A. Rice and S. Merriam,
Underwater acoustic modem configured for use in
a local area network, Proc. IEEE Oceans 98
Conf., Vol. 2, pp. 634-638, Nice France,
September 1998
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Seaweb 99 engineering experimentBuzzards Bay,
MA, August 1999SSC San Diego, Delphi, Benthos,
SAIC
FreeWave 900-MHz LOS gateway Cellular Digital
Packet Data (CDPD) gateways Seaweb server 15
ATM-875 nodes Seaweb 99 firmware FDMA-6
network Node addressing Ranging Handshake
protocol Adaptive power control Remote-controlled
routing Commercial sensors
J. Rice, et al, Evolution of Seaweb Underwater
Acoustic Networking Proc IEEE Oceans 2000
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Seaweb 2000 engineering experiment Buzzards Bay,
Aug-Sept 2000
ATM-885 modems FreeWave LOS gateway Cellular
Digital Packet Data (CDPD) gateways Asynchronous
TDMA Rerouting RTS/CTS handshake ARQ
Isobath contours at 5-meter intervals
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Demonstrated capabilitiesFRONT ocean
observatoryNational Oceanographic Partnership
Program
FRONT-3 March-June, 2001
Concept
D. L. Codiga, et al, Networked Acoustic Modems
for Real-Time Data Telemetry from Distributed
Subsurface Instruments in the Coastal Ocean
Application to Array of Bottom-Mounted ADCPs, J.
Atmospheric Oceanic Technology, June 2005
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• US participation in Canadas ICESHELF 2002 April
  experiment in the Arctic Ocean
• 80-150 m water covered by rough ice of 2-8 m
  thickness and large subsurface ridges and keels
• Upward-refracting water
• Ice-mounted Seaweb network, first test of
  acoustic networking in the Arctic
• Prepares for RDS-4 experiment with interoperable
  US and Canadian ASW sensor nodes

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Demonstrated capabilitiesFBE India June 2001
Racom buoy

• (Prior Seaweb tests with USS Dolphin submarine
  Sublinks 98, 99, 2000)
• 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

Experimental DADS sensor node
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
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Seaweb message exampleMulti-Access Collision
Avoidance (MACA) Internet Protocol (IP)

• Fixed routing tables
• Precursor to Seaweb cellular routing

Source node
G. Hartfield, Performance of an Undersea Acoustic
Network during Fleet Battle Experiment India, MS
Thesis, Naval Postgraduate School, Monterey, CA,
June, 2003
Destination node
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Demonstrated capabilitiesSeaweb network with
UUVsUS/Canada collaborationGulf of Mexico, Feb
1-8, 2003
UUV nose section
Iridium satellite radio links
Over-the-horizon command center
Shipboard command center
2 Racom buoy gateway nodes
FreeWave radio links

• Mobile gateway nodes
• Mobile sensor nodes
• 200 km logged by UUVs
• 300 hrs logged by UUVs
• Node-to-multinode comm/nav

6 fixed repeater nodes
3 glider UUV mobile nodes
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Seaweb navigation developmentSeaweb 2005 UUV
ExperimentsMonterey Bay, May 9-11, July
20-22St. Andrews Bay, December 5-9
GPS satellite constellation
Iridium satellite constellation
Racom buoy gateway node
Shipboard command center
ARIES UUV
M. Hahn, Undersea Navigation via a Distributed
Acoustic Communications Network, MS Thesis, Naval
Postgraduate School, June 2005
S. Ouimet, Undersea Navigation of a Glider UUV
using an Acoustic Communications Network, MS
Thesis, Naval Postgraduate School, Sept 2005
Slocum UUV
constellation of 6 Seaweb repeater nodes fixed
on seabed
EMATT UUV
M. Reed, Use of an Acoustic Network as an
Underwater Positioning System, MS Thesis, Naval
Postgraduate School, June 2006
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Demonstrated capabilityAll Seaweb
communications yield the node-to-node range as a
by-product of the link-layer RTS/CTS
handshake.The broadcast ping command returns
ranges to all neighboring nodes.
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Seaweb cellular grid deployment Theater ASW
Experiment TASWEX 04 Submarine comms _at_ speed
depth (CSD)
Average speed 6.5 knots Average 1 repeater every
20 min
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(No Transcript)
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Seaweb 2004 grid post mortem
Impacted by trawling along the 300-m isobath3
nodes removed, 6 nodes displaced or damaged
FINEX
FINEX
H. Kriewaldt, Communications Performance of an
Undersea Acoustic Wide-Area Network, MS Thesis,
Naval Postgraduate School, December 2005
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Seaweb 2005 experimentFebruary 2005, Panama
City, FL

• SRQ link-layer mechanism
• NSMA (Neighbor Sense Multiple Access, a
  cross-layer variation on CSMA)
• Ranging and node localization
• Iridium-equipped Racom buoy
• Compressed image telemetry
• NPS, SSCSD, CSS, Benthos

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Demonstrated capabilitySelective 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 B
RTS
2. Node B is prepared to receive a large Data
packet as a result of RTS/CTS handshaking.
1. Node A initiates a link-layer dialog with
Node B.
CTS
HDR
4. Node B receives 12 subpackets successfully
4 subpackets contained uncorrectable bit errors.
3. Node A transmits a 4000-byte Data packet
using 16 256-byte subpackets, each with an
independent CRC.
5. Node B issues an SRQ utility packet,
including a 16-bit mask specifying the 4
subpackets to be retransmitted.
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.
SRQ
6. Node A retransmits the 4 subpackets specified
by the SRQ mask.
HDR
9. Node B successfully receives and processes
Data packet.
SRQ
HDR
J. Kalscheuer, A Selective Automatic Repeat
Request Protocol for Undersea Acoustic Links, MS
Thesis, Naval Postgraduate School, June 2004
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Seaweb telesonar repeater node

• Seaweb telesonar modem, circa 2000-2007
• Texas Instruments TMS320C5410 DSP
• Teledyne Benthos COTS hardware
• US Navy firmware
• Spectral bandwidth 5 kHz (9-14 kHz)
• SL 174 dB (typ) re 1µPa _at_ 1m
• Modulation Multi-channel 4-FSK
• Forward Error Correction
• Raw bit rate 2400 bit/s
• Data packets 800 b/s
• Utility packets 150 b/s
• DI 0 dB (omni)
• DI 0 dB (omni)

K. Scussel, Acoustic Modems for Underwater
Communications, Wiley Encyclopedia of
Telecommunications, Vol. 1, pp. 15-22,
Wiley-Interscience, 2003
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Small Business Innovative ResearchSBIR N03-224
is producing the 4th-gen telesonar
modemContractor Teledyne Benthos,
Inc.Sponsor PEO C4I Space, PMW 770

• Spectral bandwidth up to 20 kHz, Operating
  frequency up to 70 kHz
• Processing speed increased by 2X, Memory
  increased by 20X
• Xmit efficiency improved by 50, Rcvr efficiency
  improved by 50
• One new digital board can support 4 T/R boards
  (for multi-band, MIMO, spatial diversity, etc)
• SBIR Ph-2 Option will integrate SBIR N99-011
  directional ducer (Image Acoustics, Inc)
• SBIR Ph-3 5-year delivery-order contract being
  negotiated by SSC San Diego

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Current workThe Seaweb network organizes and
maintains itself under the control of autonomous
master nodes or Seaweb servers at command centers
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Current researchAdaptive modulation
Reconstruct transmitted waveform
Demodulate RTS transmission
RTS
Estimate channel scattering function
CTS
Specify Data-packet comms parameters
Determine h(t, t ) / Doppler / SNR
S. Dessalermos, Undersea Acoustic Propagation
Channel Estimation, MS Thesis, Naval Postgraduate
School, Monterey, CA, June 2005
Data
Map channel characteristics against available
repertoires and signal techniques
Decision
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Current researchAsymmetric links
Low-rate C2
Submarine
High-rate data telemetry
Autonomous node
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Unet through-water acoustic signaling range
regimesCategorized at Unet Workshop 5 and
refined at Unet Workshop 6
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Acoustic link budget
Each term in the standard radio link budget is
analogous to specific quantities in the sonar
equation. SNR(f) PSL(f) TL(f)
AN(f) DIxmt(f) DIrcv(f) We develop the
acoustic link budget as a wideband model because,
unlike most radio channels, the acoustic channel
exhibits strong frequency dependency.
PSL pressure spectrum level
AN
DIxmt
DIrcv
TL
SNR
Pxmt
Prcv
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Sonar equation analysis (TLAN) for 500-m range
and 4 noise spectra
TL NSL (dB re 1µPa)
Frequency (kHz)
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Current researchSeastar local-area networks

• Asymmetric links high-BW links from peripheral
  nodes to central node low-BW links from central
  node to peripherals and peer-to-peer
• Point-to point communications at short ranges (50
  to 500 m) employ the 30-100 kHz band

• Data are fused/beamformed at the central node
• Seastar LAN increases the carrying capacity of
  the undersea environment by an order of magnitude
• Central node reports compressed information
  through the wide-area network
• Applications include sensor arrays, sensor
  clusters, autonomous MCM vehicles, and SDV/DDS
  dive teams
• DADS magnetometer array a near-term pilot
  application
• Prototype Seastar at AUVfest 2007, 2 NPS thesis
  students
• ONR 321MS 6.2 funding

Seaweb WAN
Seastar LAN
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Over 40 Seaweb deploymentsSpirally developed USW
com/nav capability
Iceweb, 2002
Q272 Seaweb GoM, 2003
RDS-4, 2002
FRONT-4, 2002
TASWEX04
Seaweb NSW, 2004