Multi-Stream Transmission in Massive MIMO Systems With Full-Duplex Bi-Directional Communication Links

This paper considers a full-duplex (FD) multi-user massive multiple-input multiple-output system where the base station (BS) and user equipment (UE) bi-directionally transmit and receive multiple independent data streams over the same frequency band. The BS and UEs are equipped with a large-scale antenna array. Accounting for imperfect channel state information, we derive the closed-form expressions for the achievable sum-rate and sum spectral efficiency (SE) for the proposed model using maximum-ratio combining and zero-forcing detection. The analytical solutions are verified with simulations. In addition, our analytical results highlight the benefits of multi-stream transmission and show an improved SE for fewer UEs. Moreover, the results show that increasing the antenna array size helps combat self-interference.