5,692 research outputs found
Cooperative Transmission for Underwater Acoustic Communications
Underwater acoustic channels normally have low data rate, long propagation delay, severe multipath effect, and time varying fading. Cooperative transmission is a new wireless communication technique in which diversity gain is achieved by utilizing relay nodes as virtual antennae. In this paper, we investigate cooperative transmission techniques for underwater acoustic communications. First, we study the performance of several cooperative transmission schemes, originally designed for radio communications, in an underwater scenario. Second, by taking advantage of the low propagation speed of sound, we design a new wave cooperative transmission scheme. In this scheme, the relay nodes amplify the signal received from the source node, and then forward the signal immediately to the destination. The goal is to alter the multipath effect at the receiver. Third, we derive the performance upper bound for the proposed wave cooperative transmission scheme. The simulation results show that the proposed wave cooperative transmission has significant advantages over the traditional direct transmission and the existing cooperative transmission schemes originally designed for radio wireless networks. ©2008 IEEE
Cooperative underwater acoustic communications
This article presents a contemporary overview of underwater acoustic communication (UWAC) and investigates physical layer aspects on cooperative transmission techniques for future UWAC systems. Taking advantage of the broadcast nature of wireless transmission, cooperative communication realizes spatial diversity advantages in a distributed manner. The current literature on cooperative communication focuses on terrestrial wireless systems at radio frequencies with sporadic results on cooperative UWAC. In this article, we summarize initial results on cooperative UWAC and investigate the performance of a multicarrier cooperative UWAC considering the inherent unique characteristics of the underwater channel. Our simulation results demonstrate the superiority of cooperative UWAC systems over their point-to-point counterparts. © 1979-2012 IEEE
Federated Meta Learning Enhanced Acoustic Radio Cooperative Framework for Ocean of Things Underwater Acoustic Communications
Sixth-generation wireless communication (6G) will be an integrated
architecture of "space, air, ground and sea". One of the most difficult part of
this architecture is the underwater information acquisition which need to
transmitt information cross the interface between water and air.In this
senario, ocean of things (OoT) will play an important role, because it can
serve as a hub connecting Internet of things (IoT) and Internet of underwater
things (IoUT). OoT device not only can collect data through underwater methods,
but also can utilize radio frequence over the air. For underwater
communications, underwater acoustic communications (UWA COMMs) is the most
effective way for OoT devices to exchange information, but it is always
tormented by doppler shift and synchronization errors. In this paper, in order
to overcome UWA tough conditions, a deep neural networks based receiver for
underwater acoustic chirp communication, called C-DNN, is proposed. Moreover,
to improve the performance of DL-model and solve the problem of model
generalization, we also proposed a novel federated meta learning (FML) enhanced
acoustic radio cooperative (ARC) framework, dubbed ARC/FML, to do transfer.
Particularly, tractable expressions are derived for the convergence rate of FML
in a wireless setting, accounting for effects from both scheduling ratio, local
epoch and the data amount on a single node.From our analysis and simulation
results, it is shown that, the proposed C-DNN can provide a better BER
performance and lower complexity than classical matched filter (MF) in
underwater acoustic communications scenario. The ARC/FML framework has good
convergence under a variety of channels than federated learning (FL). In
summary, the proposed ARC/FML for OoT is a promising scheme for information
exchange across water and air
Acoustic based tactical control of underwater vehicles
Advances in command and control of Autonomous Underwater Vehicles (AUVs) using acoustic communications are crucial to future Fleet objectives, particularly in Very Shallow Water Mine Countermeasures (VSW MCM). Understanding of the capability to redirect missions, provide relatively high rate downloads of mission information, and perform cooperative tracking for multi-vehicle systems is limited to some bounding data based on fixed node experiments. The main objectives of this dissertation were to investigate and demonstrate the capabilities of tactical acoustic control of a dynamic, operational underwater vehicle in the Very Shallow Water (VSW) and Shallow Water ocean environment. This necessarily required studies on the limitations of Acoustic Control and relatively High Data Rate Transfer when using commercial acoustic modems in underwater vehicles and investigation of their acoustic transmission characteristics. Comprehensive empirical evidence through field validation with the ARIES vehicle indicated that reduced ranges were required for successful acoustic communications in a realistic shallow water environment. A simulation was developed to demonstrate a solution for dealing with reduced range and conducting multi-vehicle behaviors for cooperative tracking and acoustic data transfer.http://archive.org/details/acousticbasedtac109459858Commander, United States NavyApproved for public release; distribution is unlimited
AUV/ASC cooperative survey
In this paper we describe a solution to perform autonomous surveys taking
advantage of a cooperative multivehicle setup. In the proposed configuration,
an ASC provides –through an USBL- absolute positioning and communications to
an AUV. Thus, by following the AUV with the surface vehicle we facilitate the reception
of USBL measurements in the AUV regardless of the extent of the mission. This
turns into an improved navigation on the AUV’s side, with the drift bounded thanks
to the absolute measurements. Experimental results show that the proposed algorithm
is able to maintain the ASC at a close distance and improve the navigation of
the AUV. Moreover, the bathymetric maps built from the AUV data are consistent
enough to enable the automatic detection of present targets and program further
localized missions in the area.Peer Reviewe
Distributed space–time cooperative schemes for underwater acoustic communications
Author Posting. © IEEE, 2008. This article is posted here by permission of IEEE for personal use, not for redistribution. The definitive version was published in IEEE Journal of Oceanic Engineering 33 (2008): 489-50, doi:10.1109/JOE.2008.2005338.In resource limited, large scale underwater sensor networks, cooperative communication over multiple hops offers opportunities to save power. Intermediate nodes between source and destination act as cooperative relays. Herein, protocols coupled with space-time block code (STBC) strategies are proposed and analyzed for distributed cooperative communication. Amplify-and-forward-type protocols are considered, in which intermediate relays do not attempt to decode the information. The Alamouti-based cooperative scheme proposed by Hua (2003) for flat-fading channels is generalized to work in the presence of multipath, thus addressing a main characteristic of underwater acoustic channels. A time-reversal distributed space-time block code (TR-DSTBC) is proposed, which extends the dual-antenna TR-STBC (time-reversal space-time block code) approach from Lindskog and Paulraj (2000) to a cooperative communication scenario for signaling in multipath. It is first shown that, just as in the dual-antenna STBC case, TR along with the orthogonality of the DSTBC essentially allows for decoupling of the vector intersymbol interference (ISI) detection problem into separate scalar problems, and thus yields strong performance (compared with single-hop communication) and with substantially reduced complexity over nonorthogonal schemes. Furthermore, a performance analysis of the proposed scheme is carried out to provide insight on the performance gains, which are further confirmed via numerical results based on computer simulations and field data experiments
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
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