Descrição
Abstract—Underwater acoustic networks (UANs) are an
emerging technology for a number of oceanic applications,
ranging from oceanographic data collection to surveillance applications.
However, their reliable usage in the field is still an open
research problem, due to the challenges posed by the oceanic
environment. The UAN project, a European-Union-funded initiative,
moved along these lines, and it was one of the first cases
of successful deployment of a mobile underwater sensor network
integrated within a wide-area network, which included above
water and underwater sensors. This contribution, together with
a description of the underwater network, aims at evaluating the
communication performance, and correlating the variation of
the acoustic channel to the behavior of the entire network stack.
Results are given based on the data collected during the UAN11
(May 2011, Trondheim Fjord area, Norway) sea trial. During
the experimental activities, the network was in operation for five
continuous days and was composed of up to four Fixed NOdes
(FNOs), two autonomous underwater vehicles (AUVs), and one
mobile node mounted on the supporting research vessel. Results
from the experimentation at sea are reported in terms of channel
impulse response (CIR) and signal-to-interference-plus-noise
ratio (SINR) as measured by the acoustic modems during the sea
tests. The performance of the upper network levels is measured
in terms of round trip time (RTT) and probability of packet loss
(PL). The analysis shows how the communication performance
was dominated by variations in signal-to-noise ratio, and how this
impacted the behavior of the whole network. Qualitative explanation
of communication performance variations can be accounted,
at least in the UAN11 experiment, by standard computation of the
CIR and transmission loss estimate.
; Grythe, Knut 
