Improvement of Multiple-input/multiple-output Time Reversal Communications in Underwater Acoustic Channels Using Adaptive Equalizers
نویسندگان
چکیده
The spatial and temporal focusing properties of time reversal methods can be exploited for undersea acoustic communications. Spatial focusing mitigates channel fading and produces a high signal-to-noise ratio at the intended receivers along with a low probability of interception elsewhere. While the temporal focusing (compression) reduces significantly intersymbol interference (ISI), there always is some residual ISI depending upon the number of transmitters, their spatial distribution, and the complexity of the channel. Moreover, a slight change in the environment over the two-way propagation interval introduces additional ISI. Using shallow water experimental data (QPSK and 8-QAM), we demonstrate that the performance of multiple-input/multiple-output time reversal communications can be further improved by cascading the received time series with adaptive equalizers to remove the residual ISI.
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