Self-interference channel characterization in underwater acoustic decoy and difficulty of interference cancellation in digital domain

As an underwater countermeasure device, the acoustic decoy features an integrated transmit-receive structure, which results in the proximal transmitted signals propagating through the underwater acoustic channel to the receiver, thereby reducing the signal-to-interference ratio and impairing the decoy's ability to suppress self-generated interference. This interference, in turn, affects the detection performance of the acoustic decoy for target signals. In this study, a model was developed to address the issue of self-interference based on the acoustic conditions under which the decoy operates. The transmission characteristics and time-varying properties of the self-interference channel were analyzed, along with the challenges present within this context. A lake experiment was conducted, and the characteristics of the self-interference transmission channel were analyzed based on the experimental data. Two primary digital-domain interference cancellation algorithms were applied to process the self-interference signals, and the limitations of these algorithms in cancelling self-interference were assessed. Finally, based on the practical application requirements and the expected performance in suppressing proximal self-interference, potential directions for the design and improvement of interference cancellation algorithms were proposed.