scholarly journals Chirp spread spectrum of orthogonal frequency division multiplexing underwater acoustic communication system based on multi-path diversity receive

2014 ◽  
Vol 63 (4) ◽  
pp. 044302
Author(s):  
Wang Yi-Lin ◽  
Ma Shi-Long ◽  
Liang Guo-Long ◽  
Fan Zhan
Keyword(s):  
Acoustic Communication ◽  
Spread Spectrum ◽  
Communication System ◽  
Orthogonal Frequency Division Multiplexing ◽  
Underwater Acoustic Communication ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Path Diversity ◽  
Underwater Acoustic ◽  
Chirp Spread Spectrum

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.

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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