Underwater surveillance has traditionally been carried out by means of surface and undersea manned vessels equipped with advanced sensor systems. This approach is often costly manpower intensive. Marine robotics an emerging technological area that enables the development networks for underwater applications. In contrast use standard assets, these are typically composed small, low‐power, possibly mobile robots, which have limited endurance, processing wireless communication capabilities. When...

We tackle the problem of channel estimation in environments that exhibit both sparse, time-varying impulse responses and impulsive noise with Symmetric alpha-Stable (SαS) statistics. Two novel frameworks are proposed for designing online adaptive algorithms exploit sparseness achieve robust performance against impulses. The first framework generates recursive least-squares (RLS)-type based on a differentiable cost function combines nonlinear methods sparse-promoting L <sub...

A new algorithmic framework for sparse channel identification is proposed. Although the focus of this paper on underwater acoustic channels, can be applied in any field where sequential noisy signal samples are obtained from a linear time-varying system. suit algorithms derived by minimizing differentiable cost function that utilizes underlying Riemannian structure as well <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L</i> <sub...

Underwater acoustic networks (UANs) have been recognized as an enabling technology for various applications in the maritime domain. The wireless nature of medium makes UANs vulnerable to malicious attacks, yet, limited consideration has given security challenges. In this paper, we outline a hybrid architecture that incorporates aspects physical layer security, software defined networking, node cooperation, cross-layering, context-awareness, and cognition. proposed envisions strategies at...

A high bit rate acoustic link for video transmission over an underwater channel is investigated. The key to achieving this objective lies in two approaches: use of efficient data compression algorithms and high-level bandwidth-efficient modulation methods. Currently available encoding standards allow at rates as low 64 kbps. While still above the limit commercially modems, prototype modems based on phase coherent modulation/detection have demonstrated successful up 30 kbps a deep-water...

Several underwater acoustic channels exhibit impulsive ambient noise. As a consequence, communication receivers implemented on the basis of Gaussian noise assumption may yield poor performance even at moderate signal-to-noise ratios (SNRs). This paper presents new channel-estimate-based decision feedback equalizer (CEB-DFE) that deals with high platform mobility, exploits any sparse multipath structure, and maintains robustness under The key component this DFE is linear-complexity channel...

The sparse direct adaptive equalization technique recently received many attentions for single-carrier underwater acoustic communications. By taking advantage of the (nonuniform) structure a equalizer (DAE), one obtains DAE with improved performance and/or reduced complexity compared its nonsparse counterpart. In this article, is revisited two contributions made: First, comprehensive comparison made existing DAEs designed proportionate-updating (PU) or zero-attracting (ZA) filtering...

Underwater acoustic channels are characterised by non-stationary fading statistics and consequently, a modulation scheme optimally designed for specific model will underperform when the channel change. This issue can be alleviated using adaptive modulation, i.e., matching of to conditions link. However, selecting signals from broad range bit rates is tedious because one needs know relationship between error rate (BER) all relevant characteristics (e.g., multipath spread, Doppler spread...

We propose a strategy for generating the same crypto-key between two trusted underwater acoustic nodes (Alice and Bob) without revealing it to an eavesdropper (Eve). Our work builds upon results of [1] where methodology string bits Alice, Bob Eve based on channel feature extraction quantization is discussed. In this paper, we aim reconcile respective Alice while minimizing information leaked Eve. To end, examine various Reed Solomon (RS) codes measure reconciliation rate Additionally, Secure...

During the Rapid Environmental Picture 2018 (REP18) sea trial, two underwater acoustic nodes (Alice and Bob) exchanged 897 channel probes over different ranges environmental conditions. In this short paper, Alice Bob independently process their received offline with aim to generate a cryptographic key based on Physical Layer Security (PLS). Using estimated Channel Impulse Responses (CIRs), they compute quantize four pre-agreed features. Eve is simulated eavesdropper who aware of PLS...

This paper aims to enhance the reliability of underwater acoustic (UWA) communications by evaluating effectiveness various Forward Error Correction (FEC) codes. In absence standardized UWA physical layer simulators, we rely on in-situ data assess performance six FEC codes: convolutional, turbo, Low-Density Parity Check (LDPC), Bose– Chaudhuri–Hocquenghem (BCH), Turbo Product Code (TPC), and polar. We examine two common payload sizes: 128-bit packets at a 1/5 encoding rate 1024-bit 1/2 rate....

High-rate underwater acoustic (UWA) channels often demonstrate long, time-varying and sparse impulse responses. Classical most used adaptive algorithms such as the recursive least-squares (RLS) algorithm normalized least-mean-square (NLMS) do not take sparseness into account when they try to match channel. Thus, performance improvement of these is possible. Sparse developed for echo cancellation, improved proportionate (IPNLMS) affine projection (IPAPA), have shown better than NLMS without...

Underwater acoustic (UWA) channels exhibit time-varying fading statistics, thus a coded modulation scheme optimally designed for specific model (e.g., Rayleigh fading) will perform poorly when the channel statistics change. Exploiting diversity via is robust approach to improve reliability of link in variety conditions. Two schemes drawn from terrestrial radio literature are compared terms their bit error rate (BER). The first combines trellis (TCM) based on an 8-phase-shift keying (8-PSK)...

This paper deals with adaptive underwater acoustic (UWA) communications where the receiver must operate at low signal-to-noise ratios (SNRs). The proposed modem is equipped a set of direct sequence spread spectrum (DSSS) signals various coding rates and modulation orders. A channel-estimate based decision feedback equalizer (CEB-DFE) used receiver. We address challenge achieving high spectral efficiencies subject to combination bit-error rate (BER) SNR constraints. To this end, selection...

As threats in the maritime domain diversify, securing data transmission becomes critical for underwater wireless networks designed surveillance of infrastructure and border protection. This has sparked interest Quantum Key Distribution (QKD). In this paper, we present an FPGA-based real-time implementation QKD system based on BB84 protocol. The unit is built a hybrid computation consisting FPGA on-board computer (OBC) interfaced with optical front-ends. A photon counting module implemented...

In the past 8 years, Centre for Maritime Research and Experimentation (CMRE) has developed, tested promoted JANUS - a robust simple modulation coding scheme to be used as first standard support interoperability in digital underwater communications. This document aims at reporting current status of look possible routes evolution this soon-to-be standard.

The paper describes the sixth edition of Rapid Environmental Picture Atlantic exercise (REPIS-Atlantic) which took place in July 2015 off Portuguese islands Azores to demonstrate coordinated operations unmanned underwater, surface, and air vehicles contributed by participants coming from Europe United States America. REP-Atlantic is a yearly demonstration targeted at advancing state art networked vehicle systems through large scale experimentation real-life operational scenarios.

This short paper presents an adaptive cross-layer routing protocol for Underwater Acoustic Networks (UANs). The proposed solution, termed NADIR Network Aware aDaptIve Routing, is fully distributed and self-adaptive. It supports the use of multiple coded modulation schemes usage crosslayer information to interact with physical layer. Link quality exploited along energy topological data in order select relay node use. performance has been evaluated considering a challenging networking...

In stark contrast to a typical underwater acoustic network (UAN) deployed in mid-latitudes, ice-covered environments make deployment difficult and expensive. A limited number of nodes must cover ranges hundreds kilometers. We tackle the design three layers: engineering, physical, networking. At engineering layer, we investigate hardware bandwidth limitations for real-world implementation. Based on proposed bandwidth, software modem equipped with waveforms achieving 1.8, 21.4, 96.2 b/s. The...

Key management is critical for the successful operation of a cryptographic system in wireless networks. Systems based on asymmetric keys require dedicated infrastructure key and authentication which may not be practical ad-hoc Underwater Acoustic Networks (UANs). In symmetric-key systems, distribution easy to handle when new nodes join network. addition, compromised all that use same are secure anymore. Hence, it desirable have dynamic way generate without relying past keys. Physical Layer...

Security is a critical consideration in Underwater Acoustic Networks (UANs) due to the importance of applications which these types networks are often employed, from military marine natural disaster prevention. Furthermore, even simple Denial Service (DoS) attacks such as jamming can be very effective disrupting communication, with significant negative consequences for applications. While has been widely studied context terrestrial networks, peculiarities propagation UANs, low speed,...

The Arctic Ocean and its various shallow passages are rapidly changing due to global warming. development of a large-scale wireless network that collects distributes oceanographic data remotely would be an extremely valuable asset researchers. This concept, however, is completely dependent upon the ability acoustically transmit digital information under water over long ranges, which not currently available. In this work, we investigate performance four transceivers based on frequency-hopping...

The growing importance of underwater networks (UNs) in mission-critical activities at sea enforces the need for secure communications (UCs). Classical encryption techniques can be used to achieve data exchange UNs. However, advent quantum computing will pose threats classical cryptography, thus challenging UCs. Currently, cryptosystems mostly adopt symmetric ciphers, which are considered computationally robust but challenge distributing secret key upfront. Post-quantum public-key (PQPK)...