Impact of Rician Phase Shifts on Multi-Pair Two-Way Full-Duplex Massive MIMO Relaying

Most of the prior research in multipair two-way full-duplex (FD) massive multiple input multiple output (mMIMO) relaying systems considers a Rician channel with a deterministic line of sight component assuming fixed locations of the transceivers. We consider random phase shifts due to phase noise and user mobility in the LoS component to capture a more realistic scenario. We estimate the phase aware and phase unaware Rician channel via the minimum mean square error and linear minimum mean square error-based estimators, respectively, and use a maximal ratio combiner/maximal ratio transmitter to derive the closed-form spectral efficiency (SE) for an arbitrary number of relay antennas. The numerical outcomes validate the correctness of the derived closed-form SE expression when compared with its ergodic equivalent. We numerically investigate the impact of phase shift and loop interference on the SE.