Underwater wireless communication by gmanoj07205

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									Underwater wireless communication

   wireless communication technology today has become part of
    our daily life

   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

   Channel depends on frequency , propagation loss and
    low speed of sound propagation

   The signal is subject to multipath propagation under
      Wave propagation
   The figures show multipath
    propagation in water

                                      tx               rx
   In shallow water, multipath
    occurs due to signal reflection
    from the surface and bottom
                                           c    distance

   In deep water, it occurs due to        tx
    ray bending
Acoustic Modem

   Dsp serves both as signal processing and

   Afe performs signal filtering and amplification
Underwater networks

   Integrated networks of
    instruments, sensors, robots
    and vehicles will operate
    together in a variety of
    underwater environments
   Depending on the
    application there are two
    types of Acoustic network
                                   “Acoustic networks, navigation and sensing
                                   for multiple autonomous underwater robotic
Types of acoustic networks

   Centralized network, nodes
    communicate through a base
   In a decentralized network,
    nodes communicate via peer-
    to-peer                         Centralized network topology

   To accommodate multiple users
    within a selected network
    should be shared
   Methods for channel sharing
    are based on scheduling or         Decentralized network
    on contention                       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
   Autonomous underwater
    vehicle (AUV) is a robot that
    travels underwater
   Modem’s fit easily into the
    AUV                             Autonomous underwater vehicle
   Low power consumption           (AUV)

   Very reliable for high level
short distance                                        platform
high                                                             sea level
bandwidth                       AUV
acoustic link

                 base      power, communications, oil
                 station                                             base


        Application to oil-field monitoring
   Environmental monitoring to gathering of
    oceanographic data

   Marine archaeology

   Search and rescue missions

   Defence
   The available bandwidth is limited
   Multipath and fading problems
   High error bit rate
   Battery power is limited
   The aim of this is to build
    acoustic communication as in fig
   This is not only the way to for
    underwater communication
   By using optical waves which
    offers higher throughput (mbps)
    over short distance (up to about
Thank you

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