Transcript
WHY UNDERWATER? The Earth is a water planet
About 2/3 of the Earth covered by oceansLargerly unexplored, huge amount resources.
Many potential applications Seismic imaging Undersea exploration Disaster prevention Mine reconnaissance Assisted navigation Distributed tactical surveillance Ocean sampling networks
UNDERWATER SENSOR NETWORKS-CHALLENGES-
High propagation delay Radio waves are extremely strongly attenuated in salt water The channel is severely impaired (multipath and fading) Energy conservation is different Underwater sensors are prone to failures because of fouling and corrosion
POSSİBLE RISKS IN A HARSH UNDERWATER ENVIRONMENT
Fishing trawlers Underwater life Failure of waterproofing
APPLICATIONS
Seismic Monitoring:A promising application for underwater sensor networks
is seismic monitoring for oil extraction from underwater fields. Cost is very high Seismic survey can only be carried out rarely.
USING A SENSOR NETWORK RAISES A NUMBER OF RESEARCH
CHALLENGES:
Extraction of data, reliably Localization, where each node to determines its location when
it is deployed or should it move Distributed clock synchronization clocks for accurate data
reporting Energy management approaches to extend sensor network
lifetime for a multiyear deployment
SOLUTIONS
Low-power Acoustic Communication: Undersea seismic monitoring of oil fields is an “all or
nothing” application.How to efficiently re-configure the network after a long
sleep period? Low power listening with flooding.
SOLUTIONS Localization:
Localization algorithms are based on the signal strength or the time-of-arrival (TOA).
TOA-based algorithms estimate distances between nodes by measuring the propagation time of a signal.
SOLUTIONS Application-Level Data Scheduling:
Acoustic networks have very limited communications bandwidth.
How to coordinate node’s transmissions in an energy-efficient way that can best utilize the channel?
acoustic radio at 20kb/s raw transfer time for one node is 16 minutes
REFERENCES
Y. Li, W. Ye, J. Wills, A. Syed and J. Heidemann. Research Challenges and Applications for Underwater Sensor Networking
E. M. Sozer, M. Stojanovic, and J. G. Proakis. Underwater acoustic networks. IEEE Journal of Oceanic Engineering, Jan. 2000.
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