BIRC: Beamspace Interference Rejection With Beam Selection for Uplink Massive-MIMO at mmWave

Modern wireless networks face increasingly complex radio propagation environments and electromagnetic congestion, motivating the use of ultra-large-scale phased arrays to enhance coverage and robustness via diverse beam configurations. However, as array sizes grow, channel state information (CSI) acquisition becomes a bottleneck — per-element estimation suffers from low SINR, while per-beam estimation, though theoretically superior due to mmWave sparsity and beamforming gain, is hindered by limitations in conventional beamformer implementations for full beamspace exploration. To overcome this, we propose a sensing-inspired beamspace interference rejection combiner (BIRC). Leveraging a photonically-enabled imaging receiver architecture, BIRC selects dominant beams from a full-dimensional analog beamspace using power-based rules and digitally synthesizes the interference rejection combiner in the reduced beamspace. This hybrid approach achieves both analog beamforming gain for accurate CSI estimation and digital inversion gain for interference suppression. Simulations using the NYU Wireless Simulator (NYUSIM) model show that BIRC approaches the performance of ideal CSI regardless of array size, enabling large arrays to support extended range or reduced power in interference-limited environments.