© WiNES 2014 @ Northeastern University

COE Lab Fair 2014

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Ø  Electromagnetic RF Waves §  Propagate through conductive salty water only at

30-300Hz § Require large antennae and high transmission power

Ø  Optical Waves §  Affected by scattering § Directional: high precision in pointing narrow laser beams § High-data rate, short-distance communications

Ø  Acoustic Waves § Used in military and civilian underwater communication

systems §  Low data rates, long distance communications

Underwater Acoustic Networks

Emrecan Demirors and Tommaso Melodia

Department of Electrical and Computer Engineering Northeastern University, Boston, MA, USA

E-mail: {edemirors, melodia}@ece.neu.edu

Why Underwater Networks ? Challenges of Acoustic Channel

How to Establish Wireless Communications Underwater?

Architecture of Our Underwater Testbed

Ø  Distributed Tactical Surveillance §  Surveillance, reconnaissance, targeting and intrusion

detection with AUVs and sensors §  Military and civilian

Ø  Environmental Monitoring §  Pollution monitoring (chemical, biological) §  Monitoring of ocean currents and winds

§ detecting climate change, understanding human activities on marine ecosystems

Ø  Equipment Monitoring §  Prevent failures in underwater equipment (Oil & Gas

industry) §  Valve failure led to oil spill in the Gulf of Mexico

Ø  Disaster Prevention §  Sensor networks that measure seismic activity from remote

locations and provide tsunami warnings to coastal areas

Future Work

The Internet Underwater

Software-defined Underwater Modem

[1] T. Melodia, H. Kulhandjian, L. Kuo, and E. Demirors “Advances in Underwater Acoustic Networking,” in S. Basagni, M. Conti, S. Giordano, and I. Stojmenovic, editors, Mobile Ad Hoc Networking: Cutting Edge Directions, pages 804{852. John Wiley and Sons, Inc., Hoboken, NJ, second edition edition, 2013. [2] E. Demirors, G. Sklivanitis, G. E. Santagati, T. Melodia, and S. N. Batalama “Design of A Software-defined Underwater Acoustic Modem with Real-time Physical Layer Adaptation Capabilities,” submitted to ACM Conference on Underwater Networks and systems (WUWNet), 2014. [3] Y. Sun, T. Melodia ”The Internet Underwater: An IP-compatible Protocol Stack for Commercial Undersea Modems," in ACM Conference on Underwater Networks and systems (WUWNet), 2013.

Field and Laboratory Tests

References

Ø  Slow propagation of sound waves in water §  1500 m/s vs. 3e8 m/s for RF waves §  Reduce the network throughput considerably

Ø  Large propagation delay variance §  Prevents accurate estimation of the round-trip-time

Ø  Strong multipath and Doppler spread §  Inter-symbol-interference §  Complex receiver design

Ø  Noise §  Man-made Noise

§  Machinery (pumps, reduction gears, power plants) §  Shipping Activity

§  Ambient Noise §  Biological and Seismic activities §  Hydrodynamics (waves, currents, tides, rain, wind)

Ø Transmission (Path) Loss §  Geometric Spreading: Spreading of sound waves §  Absorption Coefficient

§  Caused by conversion of acoustic energy into heat §  Frequency and distance dependent

Ø  High bit error rates and losses of connectivity Ø Underwater sensors prone to failures (fouling and corrosion) Ø  Transmit energy (1-20 W) is 100 times higher than in wireless

sensor networks Ø Available bandwidth severely limited Ø  Limited Battery power limited and challenging to recharge

Ø Developing and implementing new communication protocols for underwater acoustic networks

Ø Demonstrating the capabilities of the proposed SDR modem in cognitive/security problems underwater

Ø Developing new protocols for localization and time-synchronization

Need for a reconfigurable, agile, and intelligently-flexible autonomous radios to implement runtime-adaptive communication protocols.

A networking architecture for commercial underwater modems that is compatible with traditional TCP/IP Ø  Applications

§  Access underwater nodes from any Internet-connected device (e.g., smartphones, workstations)

§  Reconfigure UWA networks through SSH or FTP §  Monitor and diagnose networks in real-time

Ø  Experiments §  Transfer Data/Message from UW nodes to Internet devices (PC/

smartphone) §  Access UW nodes using SSH from our workstations §  Establish TCP connection by recompiling Linux Kernel (Increase

the TCP initial retransmission timeout) §  Create a firewall at the NAT gateway to secure access to our

UW network Ø  This research has been featured in media;

Ø  Modem Architecture §  USRP N210 and host Machine §  Power Amplifier, Voltage Preamplifier, and Electronic Switch §  Acoustic Transducer

Direct path

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Bottom reflections

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Ø  Shared, reconfigurable platform §  UDB-9000 universal deckbox with acoustic transducer §  11 Telesonar SM-75 modems §  one sonar modem

SM-75 modem

UDB-9000 Universal deckbox

Ø  Test Tank and Pool

Ø  Lake LaSalle at University at Buffalo

Ø  Lake Erie, Buffalo, NY

Ø  Physical Layer Adaptation §  PHY layer implementation on GNU Radio and Matlab § OFDM PHY layer parameter adaptation (adaptive

modulation and coding) §  Seamless switch between different communication

technologies (i.e., OFDM and DS-SS) § Robust feedback link based on a binary chirp spread

spectrum modulation (B-CSS)

PHY

LNK

Underwater Network Interface

CSMA/NAV ARQ/c-ACK

ADP Header Comp Router ProxyPacket Frag

NET

MeshRouter

Exterior Routing ICMP(v6) ARP

TRN UDP TCP

APP FTP SSH DHCP(v6)...

First ever Underwater Tweet