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US Navy Seaweb program
Seaweb
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
Sponsors: ONR, PEO LMW, SOCOM PEO IIS, CTTSO,
TRANSEC attributes
PEO C4I & Space, PEO IWS, OSD, DARPA, SBIR
Integrating sensors, UUVs, SSNs
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: [email protected], (831) 402 5666
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 program
Applied research, “Discovery & Invention”, 6.2 funding
Art of the possible for Maritime sensor networks &
Undersea Distributed Networked Systems (UDNS)
Seaweb
Iridium satellite
Ashore & afar
command centers
Racom buoy with
Iridium, FreeWave,
Telesonar
UUVs
SDV
Telesonar
repeater nodes
SSN/SSGN
with Seaweb server
ASW / ISR /
Float
MCM
nodes
Telesonar modem
Acoustic release
Weight
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SPAWAR SBIR topic N93-170 advanced and
commercialized DSP-based acoustic comms
Seaweb
SBIR contractor: Teledyne Benthos (formerly Datasonics, Inc.)
Pre-SBIR
ATM-845 ATM-865
1993-97
all analog
10 b/s FSK
SBIR Phase-2
ATM-875
1997-99
TMS320C50
2nd generation
telesonar
Spiral
development
SBIR Phase-3
ATM-885
2000-2007
TMS320C5410
3rd generation
telesonar
Spiral
development
SBIR Phase-1
ATM-850 (not shown)
1995-97
Multi-band MFSK
1st generation telesonar
Technology transfer
from MIT/WHOI
1997-2003 achievement:
Stable COTS hardware
COTS & Navy firmware
8X less expensive
40X more efficient
2007: 4th gen telesonar with
TRANSEC features
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TBED
Seaweb
Navy’s first experimental digital sensor network
1995-96
“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 experiment
Seaweb
Buzzards Bay, MA, September 1999
An undersea wireless sensor network employing
ten telesonar modems and an RF gateway buoy
41°43´
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
1 km
70°46´
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
Racom-1
41°35´
70°36´
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Seaweb ’99 engineering experiment
Seaweb
Buzzards Bay, MA, August 1999
SSC 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
Seaweb
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 capabilities:
FRONT ocean observatory
Seaweb
National Oceanographic Partnership Program
FRONT-3
March-June, 2001
FRONT-4
Jan-June, 2002
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 BottomMounted ADCPs,” J. Atmospheric & Oceanic Technology, June 2005
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Seaweb
US participation in Canada’s 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
capabilities:
Racom
buoy
Seaweb
FBE India
June 2001
(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 example:
Multi-Access Collision Avoidance (MACA)
Internet Protocol (IP)
Source
node
Seaweb
Fixed routing tables
Precursor to Seaweb
cellular routing
Destination
node
G. Hartfield, Performance of an Undersea Acoustic
Network during Fleet Battle Experiment India, MS Thesis,
Naval Postgraduate School, Monterey, CA, June, 2003
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Demonstrated capabilities:
Seaweb
Seaweb network with UUVs
US/Canada collaboration
Gulf of Mexico, Feb 1-8, 2003
UUV nose
section
Over-the-horizon
command center
Iridium satellite
radio links
Shipboard
command center
2 Racom buoy
gateway nodes
FreeWave radio links
Mobile gateway nodes
Mobile sensor nodes
200 km logged by UUVs
6 fixed
repeater nodes
3 glider UUV
mobile nodes
300 hrs logged by UUVs
Node-to-multinode comm/nav
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Seaweb navigation development
Seaweb
Seaweb 2005 UUV Experiments
Monterey Bay, May 9-11, July 20-22
St. Andrews Bay, December 5-9
Iridium
satellite
constellation
Racom buoy
gateway node
GPS
satellite
constellation
Shipboard
command center
ARIES
UUV
NPS
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
EMATT
UUV
constellation of
6 Seaweb repeater nodes
fixed on seabed
M. Reed, Use of an Acoustic Network
as an Underwater Positioning System,
MS Thesis, Naval Postgraduate
School, June 2006
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Demonstrated capability:
Seaweb
All 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.
(a) Networked command
(b) Broadcast ping
(c) Echoes
(d) Networked telemetry
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Seaweb cellular grid deployment
Theater ASW Experiment – TASWEX 04
Submarine comms @ speed & depth (CSD)
Seaweb
Average speed 6.5 knots
Average 1 repeater every 20 min
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Seaweb
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Seaweb 2004 grid post mortem
Seaweb
Impacted by trawling along the 300-m isobath
3 nodes removed, 6 nodes displaced or damaged
COMEX
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 experiment
Seaweb
February 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 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
1. Node A initiates a
link-layer dialog with
Node B.
Seaweb
Node B
RTS
CTS
2. Node B is prepared to receive a large Data
packet as a result of RTS/CTS handshaking.
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.
6. Node A retransmits
the 4 subpackets
specified by the SRQ
mask.
SRQ
HDR
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.
SRQ
9. Node B successfully receives and
processes Data packet.
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
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 @ 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 Research
SBIR N03-224 is producing the 4th-gen telesonar modem
Seaweb
Contractor: Teledyne Benthos, Inc.
Sponsor: PEO C4I & Space, PMW 770
Transmit/Receive Board
Digital Board
ATM-885
board set
New ATM-900
board set
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 work
The Seaweb network organizes and maintains
itself under the control of autonomous master
nodes or Seaweb servers at command centers
Preparation
5 days
Installation
1 day
Activation
1 hr
Seaweb
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, TRANSEC, and latency
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Current research
Seaweb
Adaptive modulation
Node A
Node B
RTS
Demodulate
RTS
transmission
Reconstruct
transmitted
waveform
Estimate channel scattering function
CTS
Specify
Data-packet
comms
parameters
Determine h(τ, t ) / Doppler / SNR
S. Dessalermos, Undersea Acoustic Propagation
Channel Estimation, MS Thesis, Naval
Postgraduate School, Monterey, CA, June 2005
Data
Decision
Map channel characteristics
against available repertoires
and signal techniques
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Seaweb
Current research
Asymmetric links
Low-rate C2
Submarine
High-rate
data telemetry
Autonomous
node
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Unet through-water acoustic signaling
range regimes
Seaweb
Categorized at Unet Workshop 5 and refined at Unet Workshop 6
Range
regime
Node-to-node
range (m)
Frequencies
(kHz)
Use
Very short
5 – 50
>100
Proximity communications,
e.g., Seamule
Short
50 – 500
30-100
Local-area networks,
e.g., Seastar
Medium
500 – 5k
8-30
Wide-area networks,
e.g. Seaweb
Long
5k – 50k
1-8
Tactical paging
Very long
50k – 500k
<1
Blue-water paging
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Seaweb
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
Pxmt
AN
DIxmt
TL
DIrcv
SNR
Prcv
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Sonar equation analysis (TL+AN) for
500-m range and 4 noise spectra
Seaweb
TL + NSL (dB re 1μPa)
PSL
W=
20kHz
Frequency (kHz)
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Current research
Seastar local-area networks
Seaweb
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
Seaweb
WAN
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
Seastar
LAN
Prototype Seastar at AUVfest 2007, 2 NPS thesis
students
ONR 321MS 6.2 funding
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Over 40 Seaweb deployments
Seaweb
Spirally developed USW com/nav capability
NPS
Iceweb, 2002
Q272 Seaweb
GoM, 2003
G
K
R
G U
GHGK
U
R
Q
FBE-I, 2001
R
R
RDS-4, 2002
FRONT-4, 2002
TASWEX04
Seaweb NSW,
2004
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