Environmental model-based time-reversal underwater communications

Abstract

Advances in underwater acoustic communications require the development of methods to accurately compensate channels that are prone to severe double spreading of time-varying multipath propagation, fading and signal phase variations. Assuming the environmen- tal information as a key issue, this work aims to improve communications performance of single-input-multiple-output transmission systems in such channels through the en- hancement of their estimates used for equalization. The acoustic propagation physical parameters of the environment between the source and the receivers are considered in the process. The approach is to mitigate noise effects in channel identification for Pas- sive Time-Reversal (PTR), which is a low complexity probe-based refocusing technique to reduce time spreading and inter-symbol interference. The method Environmental-based PTR (EPTR) is proposed that, inspired by matched field inversion, inserts physics of acoustic propagation in the channel compensation procedure through ray trace modeling and environmental focalization processing.