Repeater-Assisted Massive MIMO Full-Duplex Communications

We consider a wireless network comprising multiple singleantenna repeaters that amplify and instantaneously re-transmit received signals in a full-duplex (FD) communication setting. Specifically, we study a massive multiple-input multiple output base station that simultaneously serves multiple uplink (UL) and downlink (DL) user equipment (UE) over the same frequency band. The focus is on the problem of repeater weight optimization at each active repeater to maximize the sum of the weighted minimum spectral efficiencies (SEs) for both UL and DL UEs. The resulting non-convex optimization problem is tackled using a successive convex approximation technique. To demonstrate the effectiveness of the proposed approach, we evaluate its performance against benchmark systems with and without repeater assistance. The optimized FD design achieves SE improvements of up to 4-fold and 2.5-fold compared to its half-duplex counterpart.

💡 Research Summary

This paper investigates a novel wireless architecture that combines massive multiple‑input multiple‑output (MIMO) base stations (BS) with a swarm of single‑antenna repeaters operating in full‑duplex (FD) mode. The BS, equipped with separate transmit (M_t) and receive (M_r) antenna arrays, simultaneously serves K_dl downlink (DL) users and K_ul uplink (UL) users on the same frequency band. Each repeater instantaneously amplifies its received signal and forwards it, using a scalar weight αℓ that can be tuned individually.

The authors formulate the system‑level objective as the weighted sum of the minimum spectral efficiencies (SEs) of the DL and UL users:
max α