Full-Duplex UWA Communication System with Two Iterations

We consider full-duplex (FD) underwater acoustic (UWA) systems when the transceiver simultaneously transmits and receives in the same frequency bandwidth. The major task of the FD operation is to cancel the strong self-interference (SI) from the near-end projector. Advanced adaptive filtering algorithms have been proposed previously, capable of providing high-accuracy SI channel estimates even in scenarios with fast SI channel variations. A high level of SI cancellation can be achieved when the far-end signal is absent. However, the SI channel estimation performance is limited in FD scenarios as the far-end signal is treated as interference when estimating the near-end SI channel thus increasing the noise floor. In this paper, we propose a new FD UWA system which alternates between the near-end SI cancellation and far-end data demodulation. The FD UWA system performance is evaluated in a lake experiment using a recently developed two-element transducer. Results show 2 dB loss in the detection performance of the FD system compared to the corresponding half-duplex system in the same lake experiment.