seaweb acoustic wide-area networks for undersea sensor grids

Seaweb Acoustic Wide-Area Networks

for Undersea Sensor Grids

Joe Rice, Chris Fletcher, Bob CreberSPAWAR Systems Center, San Diego

rice @ spawar.navy.mil (831) 656-2982

Dave Johnson, ONR 321 Littoral ASW FNC (DADS)Don Davison, ONR 321 Discovery (Telesonar)

Larry Green, ONR 321 Discovery (Sealan)Jim Eckman, ONR 321 NOPP (FRONT)

Doug Harry, ONR 36 (SBIRs)LCDR John King, NWDC (Sublink)

Space & Naval Warfare Systems Center, San Diego 2

Seaweb

Seaweb Communication & Navigation

CONCEPT OF OPERATIONS

Use telesonar digital communications to form deployable autonomous distributed sensor networks with:

• wide-area coverage• architectural flexibility• environmentally adaptive wireless links• self-configuring ad hoc topologies• fixed sensor nodes and repeater nodes• fixed and mobile peripheral nodes, e.g. bi-static projectors and UUVs• fixed and mobile gateway nodes linked to command centers

submerged, afloat, aloft and ashore

Extend network-centric C4ISR into

the undersea battlespace

Rice, “Telesonar signaling and seaweb underwater wireless networks,” Proc. NATO New Information Processing Techniques for Military Systems,” October 2000


Seaweb

Background: 2nd-generation telesonar modem was developed through a SPAWAR-sponsored SBIR phase-2 contract to Datasonics

ATM-885 3rd-generation telesonar modem was developed through an ONR-sponsored SBIR phase-3 contract to Datasonics (now Benthos)

Recent Navy enhancements: TMS320C5410 DSP chip Improved low-power wake-up Moderate-power addressing Modularized type-A algorithms Utility packets Probe signals Seaweb protocols Partial-band modes Adaptive power control


Seaweb

2 Racom gateway buoys

2 DADS sensors

10 telesonar repeaters

USS Jefferson City equipped with sublink as a BSY-1 TEMPALT

Ashore ASW command center

GCCS-M links to fleet

Flawless ops for entire 4-day test period

FBE India June 2001


SeawebPROBLEM:

Littoral undersea environments impair signal propagation

APPROACH:

Low-data-rate, spread-spectrum, channel-tolerant, secure RTS utility packet initiates the telesonar link and uniquely addresses the intended receiver node

Received processes RTS as a channel probe, permitting estimation of prevailing scattering function and identification of viable signaling options

CTS utility packet fully specifies the format for ensuing DATA transmission

DATA packet has optimal coding, modulation, bit-rate, and power

PAYOFF: Channel-adaptive modulation enables undersea networks with security, reliability, efficiency, and low cost

Telesonar undersea digital communications

A BRTSRTS

CTSCTSDATADATA

9 bytes9 bytes

Rice, et al, “Adaptive modulation for undersea acoustic telemetry,” Sea Technology, May 1999

ARQARQDATADATA

up to 2 kbytes9 bytesup to 2 kbytes


Seaweb

Telesonar message exampleTelesonar message example

RT

SCTS

DA

TA

RTS

RT

S

RTS

CTS

CT

S

CTS

DATA

DA

TA

DATA


Seaweb

The seaweb server interfaces the undersea network and the client systems

Seaweb networks connect to manned command centers via radio, acoustic,

wire, and fiber gateway links

Other Command CentersOther Command CentersOther Command CentersOther Command Centers

seawebN

seaweb1

seaw

eb s

up

er s

erve

r

passive Seaweb servers

Command CenterCommand Center

“net-

centric”

C4ISR

SensorStation

N

TCP / IP

TCP / IP

SensorStation

1

Fletcher, et al, “Undersea acoustic network operations through a database-oriented server/client interface,” Proc. IEEE Oceans, November 2001


SeawebFBE-I seaweb service

DADS - shore links

(61 ASW contact reports)

DADS - sub links (listen-all)

Shore - sub links (cellular-like)

Shore - DADS links

Sub - shore link (122 messages)

Sub - DADS link

Shore - repeater links

Sub - repeater links

Approx 793 MAC-layer transmissions (up to 3700 m)

135 ARQ-prompted retries


Seaweb

FBE-I Seaweb serviceFBE-I Seaweb service

DADS - shore links (61 ASW contact reports)

Sub - shore links (122 messages)

Approx 793 transmissions


121 one retransmission

5 two retransmissions

9 three retransmissions

2253 total RTS

1753 total CTS

Creber, et al, “Performance of undersea acoustic networking using RTS/CTS handshaking and ARQ transmissions,” Proc. IEEE Oceans, November 2001


Seaweb

FBE-I Seaweb FBE-I Seaweb serviceN

um

ber

of

Mes

sag

e H

op

s

Number of ARQs per Message Hop

0 1 2 3

DADS - shore links (61 ASW contact reports)

Sub - shore links (122 messages)

Approx 793 transmissions


121 one retransmission

5 two retransmissions

9 three retransmissions

2253 total RTS

1753 total CTS

Creber, et al, “Performance of undersea acoustic networking using RTS/CTS handshaking and ARQ transmissions,” Proc. IEEE Oceans, November 2001


Seaweb

ThroughputFBE-I June 20-23

# o

f m

ess

age

s

# o

f b

yte

s


Seaweb

Packet latencySubmarine to ASWCC, FBE-I June 22

0:01:00

0:02:00

0:03:00

0:04:00

0:05:00

0:06:00

0:07:00

0:08:00

0:09:00

0:10:00

Packet number

Lat

ency

(m

inu

tes)

0

1

2

3

4

5

6

7

8

9

10 Nominal latency about 1 minute

Small deviations caused by network route variations

Large latencies caused by network interference or poor channel forcing the automatic use of handshake retries and/or ARQs

Dropped packets caused by inappropriate cellular addressing by submarine

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


Seaweb

FRONT ocean observatory

FRONT-3, March-June, 2001


Seaweb

Seaweb 2001 included the Hydra off-board sensor against USS Dolphin

9-week experiment culminating in the annual Seaweb 2001 firmware

CDPD modems used extensively for gateway comms

Network header introduced for machine-to-machine networked communications

ARQ formalized as a separate dialog

RCPT and ACK utility packets implemented


Seaweb

US participation in international ICESHELF 2002 experiment

Ice-mounted seaweb network

First test of acoustic networking in the Arctic Ocean

First integration of Canadian UCARA sensor as a seaweb node

Prepares for RDS-4 experiment with interoperable US and Canadian ASW sensor nodes

Iceweb 2002, April 2002


Seaweb

Portable undersea comm/nav rangesteaming with NUWC Keyport

Ping/Echo utility packet dialogsBroadcast ping produces staggered echoes from all receiversMobile node can track own position, and range can track mobile nodeFBE-I demonstrated the fundamentals of this seaweb application


Seaweb

Mobile GatewaySlocum UUV Glider

SBIR Phase II awarded to produce mobile gateway communication models:

Replace acoustic tracking system with telesonar modem

Move acoustic transducer to nose area

Incorporate mobile gateway missions into operating profile

Reserve buoyancy increase to allow better antenna height

New antenna designs for LOS and L-Band SATCOM radios

New nose cone, with new modem and altimeter transducers

Slocum Low-power Mobile Ocean Profiler sponsored by ONR 322OM

– Buoyancy driven– CTD sensor– GPS receiver and data radio– Antennas located on tail fin– Designed especially for shallow

water—can operate in less than 10 feet of water

Webb Research Corporation


SeawebAPL/UW Seaglider and

Webb Research SLOCUM glider serve as mobile autonomous gateway/master nodes


SeawebSummary

Seaweb is a wide-area network for sensor grids Fixed: DADS, Hydra, Kelp, UCARA, FRONT, Wetnet Mobile: SLOCUM, ARIES, EMATT Moored: Racom, Freewave, CDPD, Satcom options

Sealan is a local-area network for sensor clusters Centralized networks with asymmetric links DARWIN, oceanographic moorings, sensor uploads to

servicing UUVs, dive teams, MCM swarms Central nodes are Seaweb-compatible

Sublink permits submarine access USS Dolphin, Sublinks ’98, ’99, 2000 USS Jefferson City, Sublink 2001, FBE-I


Seaweb

Back-up slides


Seaweb2-node MAC-layer state diagram

idle

Xmt RTS

Rcv CTS

Xmt DATA

Rcv ACK/ARQ

idle

Rcv RTS

Xmt CTS

idle

Rcv DATA

Xmt ACK/ARQ

idle

Timeout

Timeout

or ARQ

Wake up

RTS

ACK

ARQ

Node A Node B


Seaweb

Sound speed profiles obtained from CTD measurements before and after the experiment.

FBE-I acoustic propagation

Ray-trace diagram for a bottom source and typical sound speed profile for the region. Ray launch angles extend from 0 to 20 at 0.5 increments. Bottom reflected paths are omitted for clarity.

Simulated impulse responses for a bottom-deployed source and receiver for five source ranges from 1 to 5 km at 1-km increments.

Baxley, et al, “Shallow-water acoustic communications channel modeling using three-dimensional Gaussian beams,” Proc. MTS Ocean Community Conf., November 1998


Seaweb

Sealan operates with situationally adaptive multi-access modes

Other multi-access modes: Scheduled TDMA Asynchronous TDMA CDMA/FDMA Clandestine modes Hybrid modes Handshaking modes Full-duplex modes

Token TDMA

Polled TDMA


Seaweb

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

Preparation 10 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, covertness, and latency


SeawebSeaweb 2002-2003 experiments

FRONT-4, US Eastern seaboard Jan-June 2002

Signalex, San Diego Bay April 2002

HF Signalex, San Diego Bay April 2002

Iceweb 2002, Arctic Ocean April 2002

Wetnet 2002, San Diego Bay May 2002

Seaweb 2002, Buzzards Bay July-Aug 2002

DADS-D, San Diego Bay September 2002

RDS-4, Halifax, Canada Sept-Oct 2002

DADS-D, San Diego Loma ShelfNovember 2002

Asymmetric links, Monterey Bay July-Dec 2002

FBE-K Summer 2003

Singapore Fall 2003

seaweb acoustic wide-area networks for undersea sensor grids

Documents

undersea networks

undersea battlespacerice

undersea acoustic telemetry

undersea sensor gridsjoe

littoral undersea environments

telesonar link

spawarsponsored sbir

channeladaptive modulation