1

SeawebUS Navy Seaweb program Undersea acoustic sensing, signaling, communications & networks

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@navy.mil, (831) 402 5666

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

J. Rice, “Enabling Undersea FORCEnet with Seaweb Acoustic Networks,” Biennial Review 2003, SSC San Diego TD 3155, pp. 174-180, Dec 2003

2

SeawebUS Navy Seaweb programApplied research, “Discovery & Invention”, 6.2 fundingArt of the possible for Maritime sensor networks & Undersea Distributed Networked Systems (UDNS)

Iridium satellite

Ashore & afarcommand centers

Racom buoy withIridium, FreeWave,

Telesonar

UUVs

SDV

SSN/SSGNwith Seaweb server

Telesonar repeater nodes

ASW / ISR / MCMnodes

Float

Telesonar modem

Acoustic release

Weight

3

SeawebSPAWAR SBIR topic N93-170 advanced and commercialized DSP-based acoustic comms

SBIR contractor: Teledyne Benthos (formerly Datasonics, Inc.)

SBIR Phase-1ATM-850 (not shown)

1997-2003 achievement:Stable COTS hardwareCOTS & Navy firmware8X less expensive40X more efficient

1993-97

all analog

10 b/s FSK

Pre-SBIRATM-845 ATM-865

1997-99

TMS320C50

2nd generation telesonar

Spiral development

SBIR Phase-2ATM-875

2000-2007

TMS320C5410

3rd generation telesonar

Spiral development

SBIR Phase-3ATM-885

1995-97

Multi-band MFSK

1st generation telesonar

Technology transfer from MIT/WHOI

2007: 4th gen telesonar with TRANSEC features

4

SeawebTBEDNavy’s first experimental digital sensor network1995-96

“TBED” Telemetry Buoy Environmental DataNSWC Coastal Systems Station, Panama City, FLObjective: telemeter environmental data from distributed seafloor sensor nodes to one or more gateway nodes

Sea test in 1996Gulf of Mexico, 60 km offshore Panama City, 45-m water8-km node-to-node ranges achieved4 Datasonics ATM-850 telesonar modems150-bit/s, 1024-bit messages

Flooding protocol designed for up to 10 nodesAdvantages: Simple, COTS modem firmware, Plug & play, Routing tables not required, Centralized control not requiredDisadvantages: Redundant communications, Not bandwidth efficient for fixed network, High latencyAnalogous 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

5

SeawebSeaweb ’98 engineering experimentBuzzards Bay, MA, September 1999An undersea wireless sensor network employing ten telesonar modems and an RF gateway buoy

70°46´

41°43´

41°35´70°36´

Isobath contours at 5-meter intervals

1 km1 km Racom-1Racom-1

ATM-875

10-m water depths

10 ATM-875 telesonar modems

3-FDMA

3 sensor nodes

FreeWave gateway

Bi-directional routing tables

Scaleable architecture

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

6

SeawebSeaweb ’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

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

Seaweb 2000 engineering experimentBuzzards Bay, Aug-Sept 2000

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SeawebDemonstrated capabilities:

FRONT ocean observatoryNational Oceanographic Partnership Program

FRONT-4 Jan-June, 2002

FRONT-3 March-June, 2001

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

Concept

9

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

10

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

(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

Racom buoy

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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

Source node

Destination node

Fixed routing tables

Precursor to Seaweb cellular routing

12

SeawebDemonstrated capabilities:

Seaweb network with UUVsUS/Canada collaborationGulf of Mexico, Feb 1-8, 2003

6 fixed repeater nodes

FreeWave radio links

3 glider UUV mobile nodes

Shipboardcommand center

Over-the-horizoncommand center

2 Racom buoy gateway nodes

Iridium satellite radio links

Mobile gateway nodes

Mobile sensor nodes

200 km logged by UUVs

300 hrs logged by UUVs

Node-to-multinode comm/nav

UUV nosesection

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SeawebSeaweb navigation development

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 satellite

constellation

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

EMATTUUV

M. Reed, Use of an Acoustic Network as an Underwater Positioning System, MS Thesis, Naval Postgraduate School, June 2006

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SeawebDemonstrated capability:

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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SeawebSeaweb cellular grid deploymentTheater ASW Experiment – TASWEX 04Submarine comms @ speed & depth (CSD)

Average speed 6.5 knotsAverage 1 repeater every 20 min

16

Seaweb

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

COMEX FINEXFINEX

H. Kriewaldt, Communications Performance of an Undersea Acoustic Wide-Area Network, MS Thesis, Naval Postgraduate School, December 2005

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SeawebSeaweb 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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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 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

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SeawebSeaweb 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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Seaweb

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

Transmit/Receive Board Digital Board

ATM-885board set

New ATM-900board set

Small Business Innovative Research

SBIR N03-224 is producing the 4th-gen telesonar modem

Contractor: Teledyne Benthos, Inc.Sponsor: PEO C4I & Space, PMW 770

22

SeawebCurrent work

The Seaweb network organizes and maintains itself under the control of autonomous master nodes or Seaweb servers at command centers

Preparation 5 days

Analyze mission requirementsMeasure or predict environmentModel transmission channelsPredict connectivity range limitsSpecify spacing, aperture, and node mixPre-program master node only

Installation 1 day

Activation 1 hr

Obey spacing constraintsTest master node link to gateway

Awaken network nodesDiscover neighbors

Initiation 2 hrs

Registration 1 hr

Obtain reciprocal channel responsePerform 2-way rangingSound own depthInitialize spectral shaping

Report link data & node configurationAssimilate data at master node

Optimization 1 hr

Operation 90 days

Compute optimal/alternate routesAssign protocols

Monitor energy, links, and gatewaysOptimize life, TRANSEC, and latency

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SeawebCurrent research

Adaptive modulation

Reconstruct transmitted waveform

Estimate channel scattering function

Map channel characteristics against available repertoires

and signal techniques

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

24

SeawebCurrent research

Asymmetric links

SubmarineSubmarineLow-rate C2

Autonomous Autonomous nodenode

High-ratedata telemetry

25

SeawebUnet through-water acoustic signaling range regimesCategorized at Unet Workshop 5 and refined at Unet Workshop 6

Range regime

Node-to-node range (m)

Frequencies (kHz)

Use

Very short 5 – 50 >100Proximity communications,

e.g., Seamule

Short 50 – 500 30-100Local-area networks,

e.g., Seastar

Medium 500 – 5k 8-30Wide-area networks,

e.g. Seaweb

Long 5k – 50k 1-8 Tactical paging

Very long 50k – 500k <1 Blue-water paging

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SeawebAcoustic link budget

Pxmt

Prcv

PSLpressurespectrum

level

SNR

AN

TL DIrcvDIxmt

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.

27

SeawebSonar equation analysis (TL+AN) for 500-m range and 4 noise spectra

W= 20kHz

PSL

TL

+ N

SL

(d

B r

e 1μ

Pa)

Frequency (kHz)

28

Seaweb

Seaweb WAN

Current research

Seastar local-area networks

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

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

Seastar LAN

29

SeawebOver 40 Seaweb deploymentsSpirally developed USW com/nav capability

FBE-I, 2001

TASWEX04

Q

GH KU

R

G

GG

K

U

R

R

R

RDS-4, 2002

Iceweb, 2002

Q272 SeawebGoM, 2003

FRONT-4, 2002

Seaweb NSW, 2004

NPS