Self-Interference Cancelation Using Phase Rotation in Full-Duplex Wireless

In this paper, we propose an analog self-interference cancelation scheme for full-duplex wireless orthogonal frequency-division multiplexing (OFDM) systems. Since the delay of the echo path is presented as a phase rotation of the baseband transmit signal at each subcarrier, the proposed scheme uses the rotated baseband signals to emulate self-interference signals for analog cancelation. While the conventional analog cancelation schemes are matched only to a single frequency, the proposed scheme can perfectly cancel self-interference at all subcarriers, as long as the phase and the gain of the echo path are given precisely. To obtain accurate estimates of the phase and the gain, we also suggest a maximum-likelihood (ML) estimator for use in the proposed scheme. Numerical results verify that the proposed scheme provides significantly enhanced suppression performance compared with the conventional scheme.