The full-duplex transmission is one of the key technologies in the 5 G communication systems, due to the ability of improving spectrum efficiency. However, the performance of the full-duplex system, with the zero intermediate frequency structure, is badly impacted by the Residual Self-Interference (RSI) and In-phase/ Quadrature (I/Q) imbalance. In this paper, the OFDM full-duplex bidirectional relaying system under the RSI and I/Q Imbalance (IQI) is investigated, in a cooperative scenario where the Decode-and-Forward (DF) protocol is considered. The outage performance of the system and its closed-form expressions are derived under Rayleigh fading channels, and the influences of the IQI and RSI on system performances are analyzed, respectively. The simulation results verify the analysis, and the conclusions are given as follows. First, the outage performance improves as decreasing of the IQI and RSI. Second, the optimal improvement of outage performance is achieved by reducing the RSI and I/Q imbalance, according the route with the steepest descent method. Third, the best way for enhancing the outage performance is chosen, by the relative position between the steepest descent route and the current coordinate of IQI-RSI.
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