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Underwater wireless communication. By: k.shiva shankar Electronics and communication engineering (06J11A04A4). INTRODUCTION.
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Underwater wireless communication By: k.shiva shankar Electronics and communication engineering (06J11A04A4)
INTRODUCTION • wireless communication technology today has become part of our daily life, the idea of wireless underwater communications may still seem far-fetched • Although cabled submersible systems remain indispensable but if high-speed communication link is to exists • wireless underwater communications with sensor technology and vehicular technology
Communication channel • The signals that are used to carry digital information through an underwater channel are acoustic signals • An underwater acoustic channel presents a communication system designer with many difficulties • The signal is subject to multipath propagation, which is particularly pronounced on horizontal channels
distance c tx tx rx Wave propagation • The figures show multipath propagation in water • In shallow water, multipath occurs due to signal reflection from the surface and bottom • In deep water, it occurs due to ray bending
inp.1 com- biner data est. data out inp.2 forward _ + decision forward feedback filter coefficients inp. K sync. Adaptation training data • Adaptive decision-feedback equalizer (DFE) • Equalizer task is to unravel the inter symbol interference
Underwater networks • Integrated networks of instruments, sensors, robots and vehicles will operate together in a variety of underwater environments • Depending on the application there two types of Acousticnetwork “Acoustic networks, navigation and sensing for multiple autonomous underwater robotic vehicles
Centralized network topology • Centralized network, nodes communicate through a base station that covers one cell • In a decentralized network, nodes communicate via peer-to-peer • To accommodate multiple users within a selected network topology, the communication channel must be shared • Methods for channel sharing are based on scheduling or on contention • Decentralized network topology
Current achievements • The modem has successfully been deployed in a number of trials • This modem is implemented in a fixed-point DSP with a floating-point co-processor • Multi-user communications each at 1.4 kbps in 5 kHz band
Autonomous underwater vehicle (AUV) • Autonomous underwater vehicle (AUV) is a robot that travels underwater • Modem’s fit easily into the AUV • Low power consumption • Very reliable for high level throughput
short distance high bandwidth acoustic link platform sea level AUV base station power, communications, oil base station base station Application to oil-field monitoring
Applications • Environmental monitoring to gathering of oceanographic data • Marine archaeology • Search and rescue missions • Defence
Conclusion • The aim of this is to build a acoustic communication as in figure • 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)