Low Complexity Non-Uniform FFT for Doppler Compensation in OFDM-Based Underwater Acoustic Communication Systems

The Doppler effect critically degrades the performance of orthogonal frequency division multiplexing (OFDM) systems in general. This problem is significantly worse for underwater acoustic (UWA) communication systems due to the distinct characteristics of the underwater channel, resulting in the loss...

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Bibliographic Details
Published in:IEEE access 2022, Vol.10, p.82788-82798
Main Authors: Nguyen, Van Duc, Thi, Hoai Linh Nguyen, Nguyen, Quoc Khuong, Nguyen, Tien Hoa
Format: Article
Language:English
Subjects:
Channel estimation
Communication
Communications systems
Compensation
Complexity
Doppler effect
Doppler frequency shift estimation and compensation
Doppler shift
Fast Fourier transformations
Fourier transforms
Impulse response
interchannel interference
non-uniform fast Fourier transform
OFDM
Orthogonal Frequency Division Multiplexing
Orthogonality
Performance degradation
Phase noise
Receivers
Symbols
Synchronization
underwater acoustic communications
Underwater acoustics
Underwater communication
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Summary:The Doppler effect critically degrades the performance of orthogonal frequency division multiplexing (OFDM) systems in general. This problem is significantly worse for underwater acoustic (UWA) communication systems due to the distinct characteristics of the underwater channel, resulting in the loss of orthogonality among sub-carriers. In order to compensate Doppler shifts, including phase noise and multipath channels in realistic communication scenarios, the joint of channel estimation and ICI reduction is often performed. However, the accuracy depends on the channel estimation and the FFT size, while this leads to increased computational complexity at the receiver. To achieve this dual goal in the actual underwater communication environment, a novel pilot structure in the frequency domain has been applied to overcome the channel impulse response (CIR) variation in a block period. The coarse Doppler shift is firstly estimated by using the received pilot signal. Afterward, the study takes advantage of the flexibility provided by non-uniform fast Fourier transform (NFFT) in choosing the sampling points to construct a fast and stable Doppler frequency Compensation Matrix-based NFFT (DCMN) to fine compensate the Doppler phase shift. Finally, this study shows the improvement of the proposed method's performance by actual experimental measurements and simulations.
ISSN:2169-3536
2169-3536
DOI:10.1109/ACCESS.2022.3196641