I. Introduction
Acoustic communications is the only feasible technology for long-range underwater data transmission. However, the available frequency bandwidth is very limited [1], [2]. To maximise the capacity of the acoustic links, we consider full-duplex (FD) communications, when a transceiver simultaneously transmits and receives data in the same frequency band [3]–[5]. The main challenge of achieving FD communication is the strong self-interference (SI) introduced by the near-end transmission [6]–[11]. Due to the high transmission power of the near-end data, we expect to deal with a high level of SI, which can be 100 dB higher than the noise floor in some communication scenarios. The residual SI will reduce the signal to noise ratio (SNR) of the desired signal and thus will degrade the system performance.