An Auxiliary Antenna Based Inter-User Interference Mitigation Approach in Full-Duplex Wireless Networks

When a full-duplex (FD) base station (BS) serves an uplink and a downlink half-duplex (HD) users, the uplink user would produce the inter-user interference (IUI) on the downlink user. In this letter, an IUI suppression scheme is proposed based on the auxiliary antenna at the downlink user. A problem of maximizing the sum achievable rate of the uplink and downlink is formulated by adjusting the weighted vector at the downlink user with limited uplink and downlink transmit power. This problem is solved by two steps. First, the optimal weighted vector at the downlink user is derived. Second, the optimal downlink power is given for a fixed uplink power and the optimal uplink power is obtained by a search method. The single-cell simulation results show that the average achievable rate of the proposed IUI suppression scheme significantly outperforms the existing schemes especially when the cell radius is small and can nearly approach the performance of the ideal FD case with IUI perfectly suppressed.