Multi-Pair Two-Way Full-Duplex Massive MIMO Relaying with Non-Ideal Hardware

We consider multipair two-way full-duplex massive multiple-input multiple-output (mMIMO) hardware- impaired relay which facilitates single-antenna full-duplex users to exchange information. The key to cost-efficient implementation of mMIMO relays is to use low cost relay hardware which are prone to impairments. These impairments however, degrade the system performance. The existing literature models the relay hardware impairments as additive noise, by ignoring the multiplicative phase noise. In this paper, we study the impact of multiplicative phase noise along with the residual hardware impairments and receiver noise at the relay. We derive a closed form spectral efficiency (SE) lower bound with maximum ratio combining/maximum ratio transmission at the relay, which is applicable for arbitrary number of relay antennas. We also numerically validate the tightness of the derived closed-form SE expression with the ergodic SE expression and analyze the impact of phase noise along with additive hardware impairments on SE.