Underwater Wireless Communication is the wireless communication in which acoustic signals (waves) carry digital information through an underwater channel.

1. By-
Abhirami P S
BCA
Assumption College

2. INTRODUCTION
 Wireless communication technology today has become
part of our daily life.
 It is difficult due to factors such as multi-path
propagation, time variations of the channel, small
available bandwidth and strong signal attenuation
especially over long distance.
 Underwater communications uses acoustic waves instead
of electromagnetic waves.

3. HISTORY
• The science of underwater acoustics began in 1490,
when Leonardo Da Vinci ,stated.
In 1687 Isaac Newton wrote his Mathematical
Principles of Natural Philosophy which included the
first mathematical treatment of sound in water.

4. 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

5. DEFICIENCY IN CURRENT
COMMUNICATION
Radio waves propagated under water at extremely
low frequencies (30Hz-300Hz) & require large
antennae and high transmission power.
Optical waves do not suffer much attenuation but are
affected by scattering.
Acoustic waves are the single best solution for
communicating underwater.

6. Radio waves do not propagate well underwater due to the high
energy absorption of water.
Therefore, underwater communication are based on acoustic
links characterized by large propagation delays.
Acoustic channels have low bandwidth.
The propagation speed of acoustic signals in water is typically
1500 m/s.
It cannot rely on the Global Positioning System (GPS).
Underwater wireless
communication
technology

7. UNDERWATER NETWORKS
o Integrated networks of instruments,
sensors, robots and vehicles will operate
together in a variety of underwater
environments
o Depending on the application there two
types of Acoustic network

8.  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
Centralized network topology
Decentralized network topology

9. MODEM
 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

10.  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
Autonomous underwater vehicle
(AUV)

11. FACTORS INFLUENCING ACOUSTIC
COMMUNICATION
Path loss : Due to attenuation and geometric
spreading.
Noise : Man-made noise and ambient noise(due
to hydrodynamics).
Multi-path propogation.
High propogation delay.

12. ADVANTAGES
Can be used to provide early
warnings of tsunamis
generated by undersea
earthquakes.
It avoids privacy leakage.
Pollution monitoring.

13. DISADVANTAGES
Battery power is limited and usually
batteries can not be recharged easily.
The available bandwidth is severely
limited.
High bit error rate.
Multipath problems.

14. APPLICATIONS
oMarine archaeology
oSearch missions
oDefence

15. CONCLUSION
o The aim of this is to build a acoustic
communication as in figure
o This topic gives the overall view of the
necessity of underwater wireless
communication and its applications.

16. REFERENCE
www.google.com
www.Wikipedia.com