In this presentation, Smitha describes an innovative project that she has developed for underwater communication using sensors.

1. CHALLENGES FOR EFFICIENT
COMMUNICATION IN
UNDERWATER ACOUSTIC SENSOR
NETWORK
Under guidance of
Dr. Basavaraj.Mathpati
Presented By: Smitha.Kulkarni

2. INTRODUCTION
DEFINITION
• Underwater Acoustic Sensor Networks (UW-ASN) consist of a
variable number of sensors and vehicles that are deployed to
perform collaborative monitoring tasks over a given area.
• Wireless Underwater Acoustic Networking is the enabling
technology for the applications of oceanographic data
collection, pollution monitoring, offshore exploration and
tactical surveillance applications.
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UW-ASN
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3. UW-ASN ARCHITECTURE
Two-dimensional Underwater Sensor Networks
 uw-sinks are equipped with two acoustic transceivers, namely a
horizontal and a vertical transceiver.
 Sensors can be connected to uw-sinks via direct links or through
multi-hop paths.
 Direct links are very likely to reduce the network throughput.
 In case of multi-hop paths the data produced by a source sensor is
relayed by intermediate sensors until it reaches the uw-sink.
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UW-ASN
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4. Architecture for 2D UW-ASN
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5. Contd….
Three dimensional underwater networks
• Three-dimensional Underwater Sensor Networks are used to
detect and observe phenomena.
• In this network sensor nodes float at different depths in order
to observe a given phenomenon.
• One possible solution would be to attach each uw-sensor
node to a surface buoy.
• The buoy pushes the sensor towards the ocean surface.
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6. Architecture for 3D UW-ASN
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7. BASICS OF ACOUSTIC COMMUNICATIONS
 Underwater acoustic communications are mainly influenced by path
loss, noise, multi-path, Doppler spread, high and variable propagation
delay.
1 PATH LOSS:
Attenuation
Geometric Spreading
2 Noise:
Man made noise
Ambient Noise
3. Multi-path:
Multi-path propagation
The multi-path geometry
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UW-ASN
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8. Contd…
4. High delay and delay variance:
• The propagation speed and large propagation delay
• The very high delay variance
5. Doppler spread:
• The Doppler frequency spread
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UW-ASN
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9. A PROTOCOL STACK FOR UW-AS
COMMUNICATIONS
 Physical Layer
1.Non-coherent modulation
2.coherent modulation
 Data Link Layer
1.contention free
FDMA and TDMA
2.non-contension free
ALOHA and CSMA
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10. Contd…...
 Network Layer
1.Proactive protocols
2.Reactive protocols
3.Geographical routing protocols
 Transport Layer
1.Flow control
2.Congestion control
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11. Major challenges in the design of
UW-ASN
• Battery power
• Available bandwidth
• Channel characteristics
• High bit error rates
• Underwater sensors are prone to failures
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12. Advantages and Disadvantages
• Advantages
1. Predict the disasters with the system and
provide efficient solutions
2. understand Impact to global environment
• Disadvantage
UWSNs are expensive
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13. Conclusion
The ultimate objective of this study is to
encourage the development of new advanced
communications techniques for efficient
underwater communication and networking for
enhanced ocean monitoring and exploration
applications.
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14. References
[1] M. Stojanovic, “Acoustic (underwater) communications,” in
Encyclopaedia of Telecommunications, J. G. Proakis, Ed. John Wiley and
Sons, 2003.
[2] J. Proakis, J. Rice, E. Sozer, and M. Stojanovic, “Shallow water acoustic
networks,” in Encyclopaedia of Telecommunications, J. G. Proakis, Ed. John
Wiley and Sons, 2003.
[3] J. G. Proakis, E. M. Sozer, J. A. Rice, and M. Stojanovic, “Shallow water
acoustic networks,” IEEE Communications Magazine, pp. 114– 119, Nov.
2001.
[4] L. Freitag and M. Stojanovic, “Acoustic communications for regional
undersea observatories,” in Proceedings of Oceanology International,
London, U.K., mar 2002.
[5] I. F. Akyildiz, W. Su, Y. Sankarasubramaniam, and E. Cayirci, “Wireless
sensor networks: A survey,” Computer Networks (Elsevier) Journal, vol.
38, no. 4, pp. 393–422, Mar. 2002.
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