Underwater wireless communication

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Underwater wireless communication

• By k.shiva shankar
• Electronics and communication
  engineering
• (06J11A04A4)

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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

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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

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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

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• Adaptive decision-feedback equalizer (DFE)
• Equalizer task is to unravel the inter symbol
  interference

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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
  Acoustic network

Acoustic networks, navigation and sensing for
multiple autonomous underwater robotic vehicles
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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

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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

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Autonomous underwater vehicle
(AUV)

• Autonomous underwater vehicle (AUV) is a robot
  that travels underwater
• Modems fit easily into the AUV
• Low power consumption
• Very reliable for high level throughput

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Application to oil-field monitoring
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Applications

• Environmental monitoring to gathering of
  oceanographic data
• Marine archaeology
• Search and rescue missions
• Defence

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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)

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Thank you