Performance Analysis of Full-Duplex AF Relaying with Transceiver Hardware Impairments

We propose a joint widely-linear I/Q imbalance compensation and self-interference (SI) cancellation scheme for amplify-and-forward (AF) full-duplex (FD) relay transceivers. Furthermore, we study the bit-error rate (BER) performance of a complete two-hop link considering hardware imperfections in transceiver electronics. Especially, if the relay gain increases, the signal-to-noise ratio (SNR) at the destination becomes higher but this also increases the SI level due to the FD operation and, as a consequence, the signal-to-interference-plus-noise ratio (SINR) at the relay input decreases. To settle this trade-off, we find numerically the optimal input back-off (IBO) for the relay power amplifier (PA) maximizing the BER at the destination. The numerical results show that the optimal IBO depends on the target BER level and the PA nonlinearity. They also show that the distortion from the PA dominates the other hardware impairments at high SNR. Finally, we show that the proposed cancellation scheme can completely eliminate the I/Q imbalance, even with mixers that have low image rejection ratio.