Self-interference canceller for full-duplex radio relay station using virtual coupling wave paths

The paper considers a coupling wave canceller for full-duplex radio relay station using adaptive antenna array. Taking advantage of the fact that coupling waves to be cancelled at the relay station consist of its own past transmitted signals, we propose a beamforming method using not only received signals at actual antenna elements but also virtual received signals, which are generated in the relay station with artificial channel impulse responses, that is to say, virtual coupling wave paths. With the approach, the proposed method can eliminate coupling waves without increasing the number of actual antenna elements even when the number of coupling wave paths is large due to high-speed communications. Computer simulation results show that the proposed method achieves coupling wave cancellation with smaller number of antenna elements than that of coupling wave paths.