Linear turbo equalization with precoding for underwater acoustic communications

Daly, Erica L.; Singer, Andrew C.; Choi, Jun Won; Preisig, James C.

doi:10.1109/acssc.2010.5757746

Cited by 8 publications

(3 citation statements)

References 9 publications

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“…On the receiver side, signals recovered through removing the modulation (by multiplying the output with the known transmitted sequence of binary data). This is similar to the approach suggested in [41]. Following this approach, we can investigate the performance of the NOFDM receiver through the real channel.…”

Section: B Sea Experimentsmentioning

confidence: 86%

A Novel Receiver Design of Nonorthogonal FDM Systems in Underwater Acoustics Communication

Anwar

Yuen

Sun

et al. 2020

IEEE Systems Journal

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While Orthogonal Frequency Division Multiplexing (OFDM) has been studied for a decade, the study of Non-Orthogonal Frequency Division Multiplexing (NOFDM) in underwater acoustics (UWA) communication has never been reported, to the best of our knowledge. Therefore, we investigate NOFDM technique for UWA communication considering the doubly-dispersive channel. The main feature of NOFDM is that it involves more closely packed subcarriers compared to OFDM, which results in higher spectral efficiency. However, this transmission suffers from severe Inter-Carrier-Interference (ICI). Since, we are considering doubly-dispersive channel, Inter-Symbol-Interference (ISI) is also encountered due to multipath propagation. Therefore, traditional receiver of NOFDM system in UWA channel, tends to have high computational complexity. Considering this problem, we design a receiver for NOFDM system, where Basis Expansion Model (BEM) is used along with Compressed Sensing (CS) channel estimation technique i.e., Orthogonal Matching Pursuit (OMP), which can effectively reduce the computational complexity. However, while implementing this technique in the real sea environment, the problem of long delay / Doppler spread is encountered due to guard intervals. Therefore, we propose the use of time domain equalizer, to mitigate the effect of long delay / Doppler spread. Simulation and experimental results based on Bit Error Rate (BER) demonstrate performance degradation due to severe interference in our proposed receiver. On the contrary, Mean Square Error (MSE) performance shows that our proposed receiver with OMP channel estimation outperforms OFDM receiver. Similarly, higher spectral efficiency gain is attained due to closely packed subcarriers.

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Section: B Sea Experimentsmentioning

confidence: 86%

A Novel Receiver Design of Nonorthogonal FDM Systems in Underwater Acoustics Communication

Anwar

Yuen

Sun

et al. 2020

IEEE Systems Journal

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“…More sophisticated mapping schemes, including trellis-coded modulation, or recursive symbol pre-coding schemes can also be employed. These are attractive for their spectral efficiency improvements [3], [4] as well as their amenability to iterative equalization and decoding methods, such as turbo-equalization. An arbitrarily sophisticated symbol mapper can be employed and tested, so long as the receiver makes use of the same additive dither as the transmitter, without the need to re-transmit data in another experiment.…”

Section: Signal Preparation For Post-experimental Researchmentioning

confidence: 99%

On the Reusability of Post-Experimental Field Data for Underwater Acoustic Communications R&D

Yang¹,

Deane²,

Preisig³

et al. 2019

Preprint

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Field data is often expensive to collect, time-consuming to prepare to collect, and even more time-consuming to process after the experiment has concluded. However, it is often the practice that such data are used for little after the funded research activity that was concomitant with the experiment is completed. Immutability of the original experimental configuration either results in re-gathering of expensive field-data, or in absence of such data, model-dependent analysis that partially captures the real-world dynamics. For underwater acoustic research and development, the standard communication pipeline might be modified to enable greater re-usability of experimental field data. This paper first characterizes the necessary modifications to the standard communication pipeline to prepare signals for transmission and subsequent recording such that research trades for different modulation and coding schemes may be undertaken post-experiment, without the need for re-transmission of additional waveforms.Then, using the modified mathematical framework, sufficient conditions for reliable post-experimental replay of the environment are recognized. Finally, techniques are discussed to collect sufficient environmental statistics such that subsequent research can be accomplished long after the experiment has been completed, and that results from a given experiment may be reasonably compared with those of another. Examples are provided using both synthetic and experimental data collected from at-sea field tests.

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“…Turbo-equalization has been shown to work well for underwater channel [19,20,25,92]. One issue with turbo-equalization is its computational complexity.…”

Section: Stojanovic Et Al Pioneered the Analysis And Application Of mentioning

confidence: 99%

Analysis of and techniques for adaptive equalization for underwater acoustic communication

Blair¹

2011

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Underwater wireless communication is quickly becoming a necessity for applications in ocean science, defense, and homeland security. Acoustics remains the only practical means of accomplishing long-range communication in the ocean. The acoustic communication channel is fraught with difficulties including limited available bandwidth, long delay-spread, time-variability, and Doppler spreading. These difficulties reduce the reliability of the communication system and make high data-rate communication challenging. Adaptive decision feedback equalization is a common method to compensate for distortions introduced by the underwater acoustic channel. Limited work has been done thus far to introduce the physics of the underwater channel into improving and better understanding the operation of a decision feedback equalizer. This thesis examines how to use physical models to improve the reliability and reduce the computational complexity of the decision feedback equalizer. The specific topics covered by this work are: how to handle channel estimation errors for the time varying channel, how to use angular constraints imposed by the environment into an array receiver, what happens when there is a mismatch between the true channel order and the estimated channel order, and why there is a performance difference between the direct adaptation and channel estimation based methods for computing the equalizer coefficients. For each of these topics, algorithms are provided that help create a more robust equalizer with lower computational complexity for the underwater channel.

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Linear turbo equalization with precoding for underwater acoustic communications

Cited by 8 publications

References 9 publications

A Novel Receiver Design of Nonorthogonal FDM Systems in Underwater Acoustics Communication

A Novel Receiver Design of Nonorthogonal FDM Systems in Underwater Acoustics Communication

On the Reusability of Post-Experimental Field Data for Underwater Acoustic Communications R&D

Analysis of and techniques for adaptive equalization for underwater acoustic communication

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