scholarly journals A low-complexity orthogonal time frequency space modulation method for underwater acoustic communication

2021 ◽  
Vol 39 (5) ◽  
pp. 954-961
Author(s):  
Yang ZHANG ◽  
Qunfei ZHANG ◽  
Yingjie WANG ◽  
Chengbing HE ◽  
Wentao SHI
Keyword(s):  
Acoustic Communication ◽  
Low Complexity ◽  
Modulation Method ◽  
Underwater Acoustic Communication ◽  
Underwater Acoustic ◽  
Frequency Space ◽  
Time Frequency ◽  
Symbol Detection ◽  
Equalization Algorithm ◽  
Infinite Norm

Compared with the orthogonal frequency division multiplexing (OFDM) modulation, the orthogonal time frequency space(OTFS) modulation has a lower peak-to-average power ratio. It can effectively resist the time selective fading caused by the Doppler effect and has significant performance advantages over doubly dispersive channels. However, the conventional OTFS linear minimum mean square error (LMMSE) method has a high complexity and is not easy to process in real time. In order to solve this problem, we propose a low-complexity equalization algorithm with infinite norm constraints based on the optimal coordinate reduction. The equalization algorithm not only obtains the optimal solution through a certain number of iterations and avoids direct matrix inversion but also equalizes infinite norm constraints to improve the symbol detection performance gains. At the same time, the OTFS delay-Doppler channel matrix we utilize is sparse and the two-norm squares of each column vector equally reduces the complexity of optimal coordinate descent. Finally, the simulation in the underwater acoustic communication scenario we designed verify the effectiveness of the proposed equalization algorithm. The simulation results show that the performance of the proposed equalization algorithm is close to that of the LMMSE method, while its low complexity is ensured.

Analysis of Underwater Acoustic Communication Channels

2013 ◽  
Vol 47 (3) ◽  
pp. 99-117
Author(s):  
Sadia Ahmed ◽  
Huseyin Arslan
Keyword(s):  
Acoustic Communication ◽  
Wave Equations ◽  
Underwater Acoustic Communication ◽  
Underwater Acoustic ◽  
Cognitive Intelligence ◽  
Frequency Space ◽  
Environmental Models ◽  
Mathematical Equations ◽  
Channel Environment ◽  
Selection Of

AbstractThe underwater acoustic communication (UAC) channel presents many difficulties such as high frequency, space, and time selectivity, frequency-dependent noise, and significant range and band limitation on transmission. Traditional UAC channel models that model such channels primarily include environmental models based on experimental data; models that are developed using mathematical equations such as wave equations, modal methods, and parabolic equations; and using statistical distributions. These methods/models are often limited in their coverage and accurate representations of every possible UAC channel environment. It is also physically impractical and cost ineffective to try to measure/estimate each channel to determine its model. In this paper, the authors will present the analysis of UAC channels according to the UAC channel environments classified and presented in a prior work by the authors, in which cognitive intelligence is used in the selection of the appropriate channel representations according to each sensed environment. To the best knowledge of the authors, this type of analysis and representation of UAC channels with respect to each UAC environment has not been addressed in the literature to date and therefore presents a significant contribution.

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