scholarly journals Optimization of Acoustic Communication Links for a Swarm of AUVs: The COMET and NEMOSENS Examples

2021 ◽  
Vol 11 (17) ◽  
pp. 8200
Author(s):  
Camila M. G. Gussen ◽  
Christophe Laot ◽  
François-Xavier Socheleau ◽  
Benoît Zerr ◽  
Thomas Le Mézo ◽  
...  
Keyword(s):  
Performance Improvement ◽  
Acoustic Communication ◽  
Orthogonal Frequency Division Multiplexing ◽  
Autonomous Underwater Vehicle ◽  
Physical Layer ◽  
Communication Process ◽  
Frame Structure ◽  
Underwater Acoustic Communication ◽  
Localization Accuracy ◽  
Communication Links

Underwater acoustic communication is a key point for performance improvement in an autonomous underwater vehicle (AUV) swarm. The communication process is essential for improving the AUVs localization accuracy for navigation and is a convenient way for sharing information among the AUVs in a network. The objective of this work, which was developed in the COMET and NEMOSENS projects, is to address the communication process required in a mobile underwater wireless network, with a focus on the proposal of an adaptive physical layer methodology. We discuss about the employed channel access method, the frame structure, and we propose the usage of an adaptive guard interval in order to ameliorate the network usage rate. We explain the physical layer aspect of the communication: the data processing at the transmitter and receiver side. In addition to that, we propose the usage of smart communications among AUVs. We design a method for adapting some physical layer parameters. The proposed approach relies only on the knowledge of the transmission geometry, and it optimizes the number of subcarriers and the cyclic-prefix length of the Orthogonal Frequency-Division Multiplexing (OFDM) system. The obtained results show a performance improvement in terms of bit-error rate when compared with the case of random parameters selection. These results corroborate the benefits of our adaptive parameters approach.

scholarly journals Parallel Resampling of OFDM Signals for Fluctuating Doppler Shifts in Underwater Acoustic Communication

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Shingo Yoshizawa ◽  
Takashi Saito ◽  
Yusaku Mabuchi ◽  
Tomoya Tsukui ◽  
Shinichi Sawada
Keyword(s):  
Conventional Method ◽  
Acoustic Communication ◽  
Orthogonal Frequency Division Multiplexing ◽  
Carrier Frequency Offset ◽  
Autonomous Underwater Vehicles ◽  
Underwater Vehicles ◽  
Error Rates ◽  
Underwater Acoustic Communication ◽  
Underwater Acoustic ◽  
Parallel Resampling

Reliable underwater acoustic communication is demanded for autonomous underwater vehicles (AUVs) and remotely operated underwater vehicles (ROVs). Orthogonal frequency-division multiplexing (OFDM) is robust with multipath interference; however, it is sensitive to Doppler. Doppler compensation is given by two-step processing of resampling and residual carrier frequency offset (CFO) compensation. This paper describes the improvement of a resampling technique. The conventional method assumes a constant Doppler shift during a communication frame. It cannot cope with Doppler fluctuation, where relative speeds between transmitter and receiver units are fluctuating. We propose a parallel resampling technique that a resampling range is extended by measured Doppler standard deviation. The effectiveness of parallel resampling has been confirmed in the communication experiment. The proposed method shows better performance in bit error rates (BERs) and frame error rates (FERs) compared with the conventional method.

scholarly journals Efficient On-Off Keying Underwater Acoustic Communication for Seafloor Observation Networks

2020 ◽  
Vol 10 (6) ◽  
pp. 1986
Author(s):  
Yan Yao ◽  
Yanbo Wu ◽  
Min Zhu ◽  
Dong Li ◽  
Jun Tao
Keyword(s):  
Acoustic Communication ◽  
Spectral Efficiency ◽  
Orthogonal Frequency Division Multiplexing ◽  
Convolutional Code ◽  
High Reliability ◽  
Underwater Acoustic Communication ◽  
Decision Threshold ◽  
Underwater Acoustic ◽  
Seafloor Observation ◽  
Observation Networks

In the cableless seafloor observation networks (SONs), the links among network nodes rely on underwater acoustic communication (UAC). Due to the energy constraint and the high-reliability requirement of the cableless SONs, the noncoherent UAC has been a preferred choice, even though a noncoherent UAC scheme generally suffers from low spectral efficiency. In this paper, we propose a high-spectral-efficiency noncoherent UAC transmission scheme which is implemented as an orthogonal frequency-division multiplexing (OFDM) system adopting the on-off keying (OOK) modulation. To simultaneously achieve high performance at a low energy consumption, an irregular recursive convolutional code (IrCC) is employed and an accumulator (ACC) is introduced to achieve a modulation with memory at the transmitter side. The ACC enables a turbo iteration between the soft demapper called the ACC-OOK demapper and the soft decoder on the receiver side, and also reduces the decoding error floor. To account for the unknown signal-to-noise ratio (SNR), an iterative threshold estimation (ITE) algorithm is proposed to determine a proper decision threshold for the ACC-OOK demapper. The IrCC is designed to match the extrinsic information transfer (EXIT) curve of the ACC-OOK demapper, lowering the SNR threshold of the aforementioned turbo iteration. Simulations and experimental results verify the superiority of the proposed noncoherent UAC scheme over conventional ones.

AUV with Variable Vector Propeller

2000 ◽  
Vol 12 (1) ◽  
pp. 60-65 ◽  
Author(s):  
Yutaka Nagashima ◽  
◽  
Takakazu Ishimatsu ◽  
Jamal Tariq Mian ◽  
Keyword(s):  
Acoustic Communication ◽  
Autonomous Underwater Vehicle ◽  
Underwater Vehicle ◽  
Logic Circuits ◽  
Underwater Acoustic Communication ◽  
Underwater Acoustic ◽  
Distributed Controller ◽  
Communication Reliability ◽  
Command Signals ◽  
And Control

We developed an autonomous underwater vehicle (AUV) with a distributed controller and underwater acoustic communication. It is compact and lightweight thanks to its variable vector propeller and control using sophisticated logic circuits. Control is very precise using underwater ultrasonic command signals. Experiments showed that the AUV moves along a path at the desired position and azimuth. We confirmed the feasibility of our algorithm for increasing ultrasonic communication reliability.

Research on Doppler and Channel Estimation for Multicarrier Spread Spectrum Underwater Acoustic Communication System

2014 ◽  
Vol 1079-1080 ◽  
pp. 752-756
Author(s):  
Yuan Wang ◽  
Zhou Mo Zeng ◽  
Yi Bo Li ◽  
Wen Zhang ◽  
Hao Feng
Keyword(s):  
Channel Estimation ◽  
Compressed Sensing ◽  
Acoustic Communication ◽  
Spread Spectrum ◽  
Orthogonal Frequency Division Multiplexing ◽  
Estimation Method ◽  
Signal Propagation ◽  
Underwater Acoustic Communication ◽  
Mobile Nodes ◽  
Underwater Acoustic

Spreadspectrum orthogonal frequency-division multiplexing (SS-OFDM), which appliesspread spectrum technique into OFDM, performs robustly in severely multipathfading underwater channels. However, this technology is sensitive to thefrequency shift. Furthermore, communication in underwater acoustic (UWA)channels is more vulnerable to Doppler effect than other wireless channels dueto the low speed of acoustic signal propagation. It presents challenges forcommunication between underwater mobile nodes. Therefore, accurate Dopplerfrequency shift estimation and compensation is important. Aself-designed receiver structure for SS-OFDM system including a novel Dopplerscale estimation method and channel estimation via compressed sensing method isproposed. The simulation and experimental results offer strong proofs for ourscheme to be a viable option for acoustic communication between underwatermobile nodes and compressed sensing method outperforms the conventionalleast-squares (LS) method in channel estimation.

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