Interference suppression in congested undersea environments

Abstract

Many acoustic channels suffer from interference which is neither narrowband nor impulsive. This relatively long duration partial band interference can be particularly detrimental to system performance. In operational networks, many "dropped" messages are lost due to partial band interference which corrupts different portions of the received signal depending on the relative position of the interferers, information source and receivers due to the slow speed of propagation. We survey recent work in interference mitigation as background motivation to develop a spatial diversity receiver for use in underwater networks and compare this multi-receiver interference mitigation strategy with a recently developed single receiver interference mitigation algorithm using experimental data collected from the underwater acoustic network at the Atlantic Underwater Test and Evaluation Center. The results indicate that both mitigation strategies are effective: parameterized interference cancellation is most effective at moderate SIRs whereas spatial diversity reconstruction is effective and realizes the most gain at high SIRs. We also apply the parametized interference cancellation to the problem of estimating mutually interfering waveforms when it is desired to know both time domain signals and find that it effectively extracts both mutually interfering linear frequency modulated (LFM) and orthogonal frequency division multiplexing (OFDM) waveforms.

A Sparse Autoencoder and Softmax Regression Based Diagnosis Method for the Attachment on the Blades of Marine Current Turbine

“…On the other hand, electrical and mechanical signals are not always enough to diagnose faults in the environment with strong currents and complex spatiotemporal variability [ 19 , 20 ]. The undersea radio signals cannot travel far due to absorption losses [ 21 ] and many acoustic signals are lost due to partial band interference [ 21 ].…”

A Sparse Autoencoder and Softmax Regression based Diagnosis Method for the Attachment on the Blades of Marine Current Turbine

“…On the other hand, the electrical and mechanical signals are not always enough to diagnose faults in environment with strong currents and complex spatiotemporal variability [18,19] The undersea radio signals cannot travel far due to the absorption losses [20] and many acoustic signals are lost due to partial band interference [20]. Therefore, this paper proposes to use image as the fault diagnosing signal, because underwater camera has been widely used which provides an effective nondestructive means for underwater measurement in various scenarios [21].…”

A Handshake-Based Protocol Exploiting the Near-Far Effect in Underwater Acoustic Networks

“…Digital Object Identifier: XX.XXXX/WCL... mance of MACA-based protocols. Specifically, we argue that packets from a NFNS can be received simultaneously, e.g., by means of multipacket reception (MPR) via interference cancellation, which has been advantageously applied to underwater communications [3], [4]. Even without MPR, simultaneous transmissions by nodes in the same NFNS can still be permitted if their destinations are different.…”

“…N = 10, T = 500 s, N bit = 1000 bits. Empirical CDF of ρ delay from(4). N = 10, T = 500 s, N bit = 1000 bits.…”