Article

Shallow water acoustic networks

Northeastern Univ., Boston, MA
IEEE Communications Magazine (Impact Factor: 4.01). 12/2001; 39(11):114 - 119. DOI: 10.1109/35.965368
Source: IEEE Xplore

ABSTRACT

Underwater acoustic networks are generally formed by acoustically
connected ocean bottom sensor nodes, autonomous underwater vehicles
(AUVs), and surface stations that serve as gateways and provide radio
communication links to on-shore stations. The quality of service of such
networks is limited by the low bandwidth of acoustic transmission
channels, high latency resulting from the slow propagation of sound, and
elevated noise levels in some environments. The long-term goal in the
design of underwater acoustic networks is to provide for a
self-configuring network of distributed nodes with network links that
automatically adapt to the environment through selection of the optimum
system parameters. This article considers several aspects in the design
of shallow water acoustic networks that maximize throughput and
reliability while minimizing power consumption

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Available from: Ethem Sozer, Jan 04, 2016
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    • "Battery replacement can be a difficult task in underwater environments, considering both time and cost. Therefore, energy is precious in underwater applications, and the minimization of the energy required per successfully transmitted bit is a very important goal [1]. The propagation environment has a great impact in the required energy per successfully transmitted information bit. "
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    ABSTRACT: Saving energy is vital in real-world underwater acoustic networks, since a lot of energy is spent to transmit acoustic waves and battery replacement is highly undesirable. In this paper, we study how the energy consumption of underwater acoustic communications can be reduced in order to extend the lifetime of underwater sensor nodes. We analyze the effect of selecting the best frequency within a given operating range for various link distances. We also consider the use of error correcting codes, and optimize the code rate and the signal to noise ratio for each link distance and frequency. Our results show that energy consumption can be greatly reduced by optimizing code rate. In particular, it is shown that uncoded transmissions can be more energy efficient for a considerable range of link distances than fixed rate convolutional codes which are popular in commercial devices. Results also show that the optimal number of average retransmissions is very small (less that one) for all studied link distances. This is an encouraging result, as acoustic communication channels impose much longer delays than RF channels and therefore schemes which require several retransmissions impose unfeasible delay constrains.
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    • "It is already known that FDMA is not suitable for UASNs due to the limited available bandwidth of underwater acoustic channels. TDMA requires a large guard time and strict synchronization , which limits its efficiency [4]. Also, it is known that CDMA-based protocols require a high-complexity design for UASNs. "
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    • "According to specific features of underwater sensor networks such as electromagnetic attenuation, intrinsic propagation delay, acoustic channel system and not accessibility [7], so we can say two general problems: A. Traffic and Low Bandwidth challenges. Sharing of bandwidth in all times and frequencies in these networks causes many challenges because of internodes contention is occurring in medium access control (MAC) sub-layer. "
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