SEMINAR REPORT ON

UNDERWATER WIRELESS COMMUNICATION

SESSION – 2014-15

ELECTRONICS & COMMUNICATION ENGG.

DHEERESH KUMAR

B.TECH. 4RD YEAR

ROLL NO. 110600102008

SURAJMAL LAXMIDEVI SAWARTHIA EDUCATIONAL TRUST &

GROUP OF INSTITUTIONS

INTRODUCTION

Underwater wireless communication is the wireless communication in which acoustic signals (waves) carry digital information through an underwater channel. Electromagnetic waves are not used as they propogate over short distances. Over the past decades, heavy cables were used to establish a high speed communication between remote end and the surface. To overcome such difficulties, underwater wireless communication has come into existence The propagation speed of acoustic signals in water is typically 1500 m/s.

It cannot rely on the Global Positioning System (GPS).

NECESSITY OF UNDERWATER WIRELESS

COMMUNICATION

Wired underwater is not feasible in all

situations as shown below-:

Temporary experiments

Breaking of wires

Significant cost of deployment

Experiment over long distances.

To cope up with above situations, we require

underwater wireless communication.

FACTORS INFLUENCING ACOUSTIC

COMMUNICATION

Path loss: Due to attenuation and geometric

spreading.

Noise: Man-made noise and ambient

noise(due to hydrodynamics)

Multi-path propogation

High propogation delay

Doppler frequency spread.

HARDWARE PLATFORM INTERFACES

Sensor Interface:

Must develop common interface with different

sensors (chemical, optical, etc.) and

communication elements (transducer) .

Wide (constantly changing) variety of sensors,

sampling strategies

Communication Interface:

Amplifiers, Transducers

Signal modulation

Hardware:

Software Defined Acoustic Modem (SDAM)

Reconfigurable hardware known to provide,

flexible, high performance implementations for

DSP applications

ACOUSTIC MODEM

Employ advanced modulation scheme and channel equalization for improved signal to noise ratio.

Employ high performance error detection and correction coding scheme which reduces bit error rate to less than 10-7

Parts of an acoustic modem:

DSP Board

AFE(Analog Front End) Board

DC/DC Converter

DATA TRANSMISSION IN MODEM

When no data is being transmitted, the

modem stays in sleep mode, it periodically

wakes up to receive possible data being

transmitted by far end modem. This results in

low power consumption. Similarly when the

data is to be transmitted , the modem

receives data from its link in sleep mode and

then switches to transmit mode and transmit

the data.

ADVANCED MODEMS AVAILABLE

UNDERWATER ACOUSTIC SENSOR

NETWORKS (UW-ASN)

Group of sensors and vehicles deployed

underwater and networked via acoustic

links, performing collaborative tasks.

Equipment

Autonomous Underwater Vehicles (AUVs)

Underwater sensors (UW-ASN)

UW-ASN COMMUNICATION ARCHITECTURE

UW-ASN COMMUNICATION ARCHITECTURE

ADVANTAGES

Can be used to provide early warnings of

tsunamis generated by undersea

earthquakes.

It avoids data spoofing.

It avoids privacy leakage.

Pollution monitoring.

APPLICATIONS

Seismic monitoring.

Pollution monitoring

Ocean currents monitoring

Equipment monitoring and control

Autonomous Underwater Vehicles (AUV)

Remotely operated vehicle(ROV)

Acoustic navigation technology for multiple AUVs.

Solar Powered AUVs

•SEARCH AND RESCUE MISSION

DISADVANTAGES

Battery power is limited and usually batteries can not be recharged easily.

The available bandwidth is severely limited.

Underwater sensors are prone to failures because of fouling, corrosion, etc.

Channel characteristics including long and variable propagation delays.

Multipath and fading problems.

High bit error rate.

CONCLUSION

The aim of this is to build a acoustic

communication.

This is not only the way for underwater

communication.

By using optical waves which offers higher

throughput (Mbps) over short distances (up

to about 100 m) .

THANK YOU