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.

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.

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.

Reliability Analysis of Turbo Code for High-Speed Underwater Acoustic Communication Based on OFDM

2013 ◽  
Vol 475-476 ◽  
pp. 832-837
Author(s):  
Lin Zhou ◽  
Lan Jun Liu ◽  
Shu Kai Chi
Keyword(s):  
Acoustic Communication ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Data Transfer ◽  
Turbo Code ◽  
Rapid Development ◽  
Underwater Acoustic Communication ◽  
Underwater Acoustic ◽  
Advantages And Disadvantages ◽  
Coding Scheme

With the rapid development of OFDM (Orthogonal Frequency Division Multiplexing) technology and its own advantages, this technology has been studied actively in underwater acoustic communication recently to improve the data transfer rate and reliability. This paper introduces the key technology of high speed OFDM underwater acoustic communication, analyzes the advantages and disadvantages, design a high-speed underwater acoustic OFDM communication coding scheme based on TURBO code, and proceeding the simulation and analysis for the OFDM system. Finally, the reliability of TURBO code in high speed underwater acoustic OFDM communication is analyzed.

scholarly journals Orthogonal Chirp Division Multiplexing for Underwater Acoustic Communication

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3815 ◽  
Author(s):  
Yiqi Bai ◽  
Pierre-Jean Bouvet
Keyword(s):  
Acoustic Communication ◽  
Orthogonal Frequency Division Multiplexing ◽  
Underwater Acoustic Communication ◽  
Water Tank ◽  
Chirp Signal ◽  
Frequency Division ◽  
Transmission Scheme ◽  
Underwater Acoustic ◽  
Fresnel Transform ◽  
Performance Results

The objective of this study is to investigate a novel Underwater Acoustic Communication (UWAC) system based on a modulated chirp signal termed as Orthogonal Chirp Division Multiplexing (OCDM). Originating from the Fresnel transform, OCDM uses chirp signals to exploit the multipath diversity of the channel, achieving a good robustness against frequency fading, especially in the underloaded scenario where only a subset of the available waveforms is modulated. The implementation of the OCDM system for the UWAC scenario is described, and the performance results over an experimental water tank and realistic replayed underwater channel are compared against the traditional Orthogonal Frequency Division Multiplexing (OFDM) transmission scheme.

Sign in / Sign up

Export Citation Format

Share Document