Spectral- and Energy-Efficiency for Massive MIMO Two-Way Full-Duplex Hybrid Processing AF Relay

We consider two-way full-duplex relaying where multiple full-duplex user-pairs exchange information via a shared hybrid full-duplex relay with large antenna array of size N. We assume that the hybrid relay has smaller number of radiofrequency (RF) chains than antennas. With zero-forcing reception (ZFR)/zero-forcing transmission (ZFT) relay processing, we derive its analytical asymptotic spectral efficiency (SE) and energy efficiency (EE) expressions with N→∞. We show that the analytical SE and EE expressions match with their exact expressions, which can only be numerically evaluated. We also numerically demonstrate that a hybrid full-duplex relay has only marginally inferior SE and EE than its full-RF chain counterpart.