Covet underwater acoustic communication based on spread spectrum orthogonal frequency division multiplexing (OFDM)

2017 ◽  
Vol 141 (5) ◽  
pp. 3990-3990
Author(s):  
Shaofan Yang ◽  
Zhongyuan Guo ◽  
Shengming Guo ◽  
Ning Jia ◽  
Dong Xiao ◽  
...  
Keyword(s):  
Acoustic Communication ◽  
Spread Spectrum ◽  
Orthogonal Frequency Division Multiplexing ◽  
Underwater Acoustic Communication ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Underwater Acoustic

scholarly journals Orthogonal Frequency Division Multiplexing Underwater Acoustic Communication System with Environmental Cognition Ability

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Jinqiu Wu ◽  
Xiaofei Qi ◽  
Kang Guo ◽  
Jiaqiong Zhou ◽  
Yi Zhang
Keyword(s):  
Communication Networks ◽  
Acoustic Communication ◽  
Orthogonal Frequency Division Multiplexing ◽  
Adaptive Modulation ◽  
Adaptive Modulation And Coding ◽  
Underwater Acoustic Communication ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Underwater Acoustic ◽  
Environmental Cognition

In UWAC (underwater acoustic communication), UWA (underwater acoustic) channels change rapidly due to varying environment conditions. AMC (adaptive modulation and coding) is an efficient technique to improve system efficiency by changing transmission parameters according to channel conditions in UWA channels. In this paper, we propose an environmental cognition orthogonal frequency division multiplexing (OFDM) UWAC system and compare it with AMC algorithm with six transmission modes together with three threshold detection algorithms. Simulation and experimental results show the effectiveness of the proposed system. The system will play an important role in future communication networks which can significantly improve the efficiency of the system.

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.

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.

scholarly journals M-ary nonlinear sine chirp spread spectrum for underwater acoustic communication based on virtual time-reversal mirror method

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Songzuo Liu ◽  
Habib Hussain Zuberi ◽  
Yi Lou ◽  
Muhmmad Bilal Farooq ◽  
Shahabuddin Shaikh ◽  
...  
Keyword(s):  
Acoustic Communication ◽  
Time Reversal ◽  
Spread Spectrum ◽  
Underwater Acoustic Communication ◽  
Half Cycle ◽  
Spreading Factor ◽  
Underwater Acoustic ◽  
Virtual Time ◽  
Chirp Spread Spectrum ◽  
Time Reversal Mirror

AbstractLinear chirp spread spectrum technique is widely used in underwater acoustic communication because of their resilience to high multipath and Doppler shift. Linear frequency modulated signal requires a high spreading factor to nearly reach orthogonality between two pairs of signals. On the other hand, nonlinear chirp spread spectrum signals can provide orthogonality at a low spreading factor. As a result, it improves spectral efficiency and is more insensitive to Doppler spread than the linear counterpart. To achieve a higher data rate, we propose two variants (half cycle sine and full cycle sine) of the M-ary nonlinear sine chirp spread spectrum technique based on virtual time-reversal mirror (VTRM). The proposed scheme uses different frequency bands to transmit chirp, and VTRM is used to improve the bit error rate due to high multipath. Its superior Doppler sensitivity makes it suitable for underwater acoustic communication. Furthermore, the proposed method uses a simple, low-power bank of matched filters; thus, it reduces the overall system complexity. Simulations are performed in different underwater acoustic channels to verify the robustness of the proposed scheme.

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