Combined adaptive time reversal and DFE technique for time-varying underwater communications

Vilaipornsawai, U.; Silva, A.; Jesus, S. M.

http://hdl.handle.net/10400.1/1624

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Authors

Vilaipornsawai, U.

Silva, A.

Jesus, S. M.

Abstract(s)

This work presents a combined geometry-adapted passive Time Reversal (pTR) and Decision Feedback Equalizer (DFE) technique for time-variant underwater communications. We consider sustainable high data rate communications between a moving source and/or a moving receiver array, i.e. there is the presence of geometry changes such as range and depth changes. Such geometry changes can be partially compensated by employing a proper frequency shift on the probe impulse response in the pTR processing. We then refer to the geometry-adapted pTR as Frequency Shift pTR (FSpTR). With dense and long receiver array, a pTR-based technique possesses pulse compression property and can eliminate Inter-Symbol Interference (ISI) problem in multipath static channels. However, with a practical-size array and time-varying channels, a residual ISI always exists. Hence, in this work, we apply an adaptive DFE to further mitigate the residual ISI from the FSpTR, and call the technique as FSpTR-DFE. Performance of the FSpTR-DFE is evaluated using both experimental and simulated data, where an information rate of 2000 bps and BPSK signaling are considered. The RADAR’07 experimental data and the simulated data of the south Elba site are considered. In both data sets, a fast moving source with speed of 1.5 m/s is considered. The results show that the FSpTR-DFE technique outperforms the FSpTR as well as the technique combining the conventional pTR with DFE.