Passive Time Reversal Acoustic Communications Through Shallow-Water Internal Waves

Song, Aijun; Badiey, Mohsen; Newhall, Arthur E.; Lynch, James F.; DeFerrari, Harry A.; Katsnelson, Boris

doi:10.1109/joe.2010.2060530

Cited by 37 publications

(17 citation statements)

References 31 publications

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“…2,3 In rich multipath fading environments (e.g., the shallow water acoustic channel), TR approaches are particularly attractive for both the array gain from multichannel combining as well as the computational savings from a significant intersymbol interference reduction at the output of the combiner. However, while adaptive DFE receivers are inherently capable of tracking a time-varying channel, TR receivers require a priori knowledge of the channel and must be supplemented with reliable channel estimation and tracking techniques.…”

Section: Introductionmentioning

confidence: 99%

“…time-varying channels, recent results showed that TR could also be applied with decision-directed channel updates and block-based processing. 3,4 When considering multiple users, each with a single transmitter, communicating simultaneously to a single receiving array without the explicit use of time, frequency, or code division, extending either class of receivers became nontrivial. While an adaptive multiuser DFE was derived to address the problem, its implementation was limited by the exponential growth in computational complexity in the number of users.…”

Section: Introductionmentioning

confidence: 99%

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Multiuser interference cancellation in time-varying channels

Cho

Song

Hodgkiss

2012

The Journal of the Acoustical Society of America

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In this letter, an adaptive time-reversal multichannel combiner is embedded within an iterative successive interference cancellation receiver. With the addition of matching pursuit, a sparse channel estimation technique, the combined receiver is shown to provide both temporal interference cancellation as well as spatial interference suppression in decoding simultaneous transmissions from separate users in a time-varying underwater acoustic environment. Experimental data collected during the KAM11 experiment illustrates that for a two-user multiple-access system, multiuser separation can be achieved.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Multiuser interference cancellation in time-varying channels

Cho

Song

Hodgkiss

2012

The Journal of the Acoustical Society of America

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“…studied for a variety of applications in underwater acoustics [5][6][7][8][9][10][11][12] and other fields [13][14][15]. A large diversity of paths is desirable in TRM applications because increasing the path diversity leads to a sharpening of the focus in the back-propagated field at the original source point and a reduction of spurious focal side lobes [7,[13][14][15][16].…”

Section: Ocean Acoustics Hydroacousticsmentioning

confidence: 99%

Application of time reversal to passive acoustic remote sensing of the ocean

et al. 2017

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Application of TimeAbstract⎯This paper investigates a novel approach to processing records of ambient noise in the ocean that are measured concurrently in spatially separated locations. The approach is a synthesis of two well-known phase-coherent signal processing techniques. At the first stage of processing, an approximation to the transient acoustic Green function is found by the method of noise interferometry. At the second stage, the approximate Green function is time reversed and back propagated from the location of one of the receivers, thereby producing a focus in the vicinity of the other receiver. Unlike the earlier work, measurements at just two points (rather than vertical array measurements) are used when the sound-propagation range is large compared to the ocean depth. The requirement for optimal focusing of the back-propagated field is shown to lead to extraction of estimates of the unknown physical parameters of the waveguide and, hence, to passive acoustic remote sensing of the ocean.Keywords: ocean acoustics, noise interferometry, time reversal DOI: 10.1134/S1063771017020038 INTRODUCTION This paper reports an investigation of a novel approach to solving inverse problems, which is based on synthesis of the noise interferometry and the timereversal technique. Roux and Kuperman [1] were the first to consider such a signal-processing technique but without application to inverse problems. We show that the combined use of the noise interferometry and time-reversal techniques allows one to use concurrent records of ambient noise at a few locations for passive acoustic remote sensing of the ocean.The proposed approach is conceptually simple and consists of three steps. At the first signal processing step, the cross-correlation function (NCCF) С AB (t) is computed from concurrent measurements of ambient noise of the ocean at locations A and B. Here, t is the time lag of the signal at B relative to the signal at A. For

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“…[23] applied single sensor passive TRM to Pattern time delay shift coding scheme (PDS), which could mitigate the ISI caused by multipath channel in shallow water environments and increase the signal propagation distance and available bandwidth. [24] investigated two types of internal wave effects for passive time-reversal communications: one is the rapid channel fluctuation (decreased channel coherence); the other is the long-term (in the scale of hours) performance degradation in the depressed waveguide when the internal waves passed through the acoustic track. [25] proposed a receiver design taking advantage of the time reversal (phase conjugation) and properties of spread spectrum sequences known as Gold sequences to improve link qualities (increase signal-to-noise (SNR) ratio and reduce bit-error-rate (BER) ) of UWA sensor networks.…”

Section: Passive Time-reversal Communicationsmentioning

confidence: 99%

Time Reversal in Underwater Acoustic Communications

Li¹,

Papson²

2012

IJCA

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How to achieve high data rate coherent underwater acoustic (UWA) communications is a challenging topic due to several unique properties of UWA environments, especially in shallow water acoustic environments. Time reversal, or phase conjugation in the frequency domain, is a process engages in achieving high data rate and reliable high frequency coherent communications in time-varying UWA environments, while reducing the system complexity significantly compared with traditional methods, such as using large arrays of sensors, or redundantly transmitting at different time. Therefore, timereversal technique has been approved to be a promising technique in future UWA communications and networks. In his paper, we will present an overview of the application of the time-reversal process to acoustic communications. The content includes basic concept and mechanism of timereversal in UWA communications, passive and active timereversal UWA communications, application challenges of the time-reversal technique in UWA communications and networks. General TermsWireless communication and signal processing

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Passive Time Reversal Acoustic Communications Through Shallow-Water Internal Waves

Cited by 37 publications

References 31 publications

Multiuser interference cancellation in time-varying channels

Multiuser interference cancellation in time-varying channels

Application of time reversal to passive acoustic remote sensing of the ocean

Time Reversal in Underwater Acoustic Communications

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