7,286 research outputs found
On the Relationship between Transmission Power and Capacity of an Underwater Acoustic Communication Channel
The underwater acoustic channel is characterized by a path loss that depends
not only on the transmission distance, but also on the signal frequency. As a
consequence, transmission bandwidth depends on the transmission distance, a
feature that distinguishes an underwater acoustic system from a terrestrial
radio system. The exact relationship between power, transmission band, distance
and capacity for the Gaussian noise scenario is a complicated one. This work
provides a closed-form approximate model for 1) power consumption, 2) band-edge
frequency and 3) bandwidth as functions of distance and capacity required for a
data link. This approximate model is obtained by numerical evaluation of
analytical results which takes into account physical models of acoustic
propagation loss and ambient noise. The closed-form approximations may become
useful tools in the design and analysis of underwater acoustic networks.Comment: 6 pages, 9 Figures, Awaiting acceptance to IEEE Oceans 08
(Conference), Kobe, Japa
Joint Optimal Design for Outage Minimization in DF Relay-assisted Underwater Acoustic Networks
This letter minimizes outage probability in a single decode-and-forward (DF)
relay-assisted underwater acoustic network (UAN) without direct
source-to-destination link availability. Specifically, a joint global-optimal
design for relay positioning and allocating power to source and relay is
proposed. For analytical insights, a novel low-complexity tight approximation
method is also presented. Selected numerical results validate the analysis and
quantify the comparative gains achieved using optimal power allocation (PA) and
relay placement (RP) strategies.Comment: 5 pages, 2 figures; accepted to IEEE Communications Letters 201
Range-only underwater target localization : error characterization
Locating a target from range measurements
using only one mobile transducer has been increased
over the last years. This method allows us to reduce the
high costs of deployment and maintenance of
traditional fixed systems on the seafloor such as Long
Baseline. The range-only single-beacon is one of the
new architectures developed using the new capabilities
of modern acoustic underwater modems, which can be
time synchronization, time stamp, and range
measurements.
This document presents a method to estimate the
sources of error in this type of architecture so as to
obtain a mathematical model which allows us to
develop simulations and study the best localization
algorithms. Different simulations and real field tests
have been carried out in order to verify a good
performance of the model proposed.Postprint (published version
Underwater acoustic slant range measurements related to weather and sea state
Underwater range measurements are key factor in underwater acoustic positioning, used in Long Base-Line (LBL) or Ultra Short Base-Line (USBL) computing techniques. These measurements are commonly carried out through acoustic communications between modems and their accuracy can be affected by different factors, such as sea state, weather conditions, and obstacles in the line of sight propagation. This is especially important in shallow waters areas, where others phenomena such as multi-path have to be considered. Therefore, range accuracy and the associated position estimation errors are an important area of research. Here, we addressed the relation between range measurements variability and sea state (i.e. currents or waves height) as proxy of real-world conditions, affecting acoustic positioning performances. For that purpose, a long-term deployment have been carried out in the underwater cabled observatory OBSEA, which provide different measurements of the sea and weather state.Peer ReviewedPostprint (published version
A novel cooperative opportunistic routing scheme for underwater sensor networks
Increasing attention has recently been devoted to underwater sensor networks (UWSNs) because of their capabilities in the ocean monitoring and resource discovery. UWSNs are faced with different challenges, the most notable of which is perhaps how to efficiently deliver packets taking into account all of the constraints of the available acoustic communication channel. The opportunistic routing provides a reliable solution with the aid of intermediate nodes’ collaboration to relay a packet toward the destination. In this paper, we propose a new routing protocol, called opportunistic void avoidance routing (OVAR), to address the void problem and also the energy-reliability trade-off in the forwarding set selection. OVAR takes advantage of distributed beaconing, constructs the adjacency graph at each hop and selects a forwarding set that holds the best trade-off between reliability and energy efficiency. The unique features of OVAR in selecting the candidate nodes in the vicinity of each other leads to the resolution of the hidden node problem. OVAR is also able to select the forwarding set in any direction from the sender, which increases its flexibility to bypass any kind of void area with the minimum deviation from the optimal path. The results of our extensive simulation study show that OVAR outperforms other protocols in terms of the packet delivery ratio, energy consumption, end-to-end delay, hop count and traversed distance
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