Apparatus, Systems and Methods for Enhanced Multi-carrier Based Underwater Acoustic Communications
Advantageous OFDM-based underwater acoustic (UWA) apparatus, systems and methods are provided according to the present disclosure. In general, OFDM transmissions over UWA channels encounter frequency-dependent Doppler drifts that destroy the orthogonality among OFDM subcarriers. The disclosed apparatus, systems, and methods use a two-step approach to mitigate frequency-dependent Doppler drifts for zero-padded OFDM transmissions over fast-varying channels: (1) non-uniform Doppler compensation via resampling to convert a "wideband" problem into a "narrowband" problem; and (2) high-resolution uniform compensation on the residual Doppler. The disclosed apparatus, systems and methods are based on block- by-block processing and do not rely on channel dependence across OFDM blocks. Thus, the disclosed apparatus, systems and methods are advantageously applicable for fast-varying UWA channels.
ZHOU SHENGLI [US]; LI BAOSHENG [US]; WILLMETT PETER [US]; STOJANOVIC MILICA [US]; FREITAG LEE [US]
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