L.P. Maia, lussacmaia@gmail.com
A. Silva, asilva@ualg.pt
S.M. Jesus sjesus@ualg.pt
LARSys, University of Algarve,
Campus de Gambelas, PT-8005-139 Faro, Portugal.
Comments: download (pdf).
Ref.: IEEE Access, Vol.6, Issue 1, pp.10041-10051, August 2017.
Abstract
This work addresses channel compensation in underwater acoustic communications by proposing a method for
inserting physical propagation modeling into a passive time-reversal (PTR) receiver. PTR is known as a low
complexity channel equalizer that uses multichannel probing for time signal refocusing, reducing
inter-symbol interference caused by multipath propagation. The proposed method aims to improve
PTR communications performance by replacing the conventional noisy channel estimates with optimized and
noiseless channel replicas computed by a numerical ray trace model. The optimization consists of
environmental focalization in a “a priori” physical parameter search space to obtain “a posteriori” channel
impulse response replicas that best matches the observed data. The results obtained on two data sets acquired
during the UAN’11 experiment in a shallow water fjord near Trondheim, in May 2011, show that the proposed
method clearly outperformed the traditional PTR by an MSE gain from 1 up to 4 dB. Channel tracking was
effective despite a reduced physical parameter search space that could be exhaustively covered with a minimal
computational effort. To the authors best knowledge this is the first successful report on the usage of a
physical parameter fed numerical model for underwater acoustic communications channel equalization with real
transmitted data in a useful underwater modem frequency band.
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