Preamble Detection for Underwater Acoustic Communications Based on Sparse Channel Identification

Preamble detection before data transmission is an important module for an underwater communication system, since false detections would bring undesirable consequences in terms of the lifetime and coexistence of underwater networks. This paper conducts a thorough investigation of preamble detection in adverse underwater acoustic channels in the presence of various external interference, such as narrowband interference, impulsive noise, partial-band partial-block-duration interference, and chirps from nearby systems-The Gaussian noise model is not sufficient. We propose two novel detection methods based on the inherent sparsity of underwater acoustic channels: The first method declares signal detection when a sparse signal reconstruction is successful, whereas the second method accumulates the correlation coefficients from multiple paths instead of just the strongest path. We study the performance of the proposed methods based on simulations and experimental data sets, where the detection thresholds are empirically obtained. Performance results testify to the clear advantages of the proposed detection methods relative to existing matched-filter based approaches in various interference conditions.