Tianyu Jiang, Kristaps Rubuls, Dan Li, Mahdieh Joharifar, Armands Ostrovskis, Anders Djupsjöbacka, Toms Salgals, Jakub Zverina, Leoš Halmo, Sandis Spolītis, Vjačeslavs Bobrovs, Oskars Ozolins, Xiaodan Pang, Rafael Zamora Puerta
To meet the demands of sixth-generation (6G) mobile networks, distributed multiple-input multiple-output (D-MIMO) systems employing geographically separated antenna units offer enhanced coverage, capacity, and efficiency. We present a practical and scalable four-transmitter D-MIMO proof-of-concept using coherent joint transmission (CJT) and analog radio-over-fiber (ARoF) fronthaul, achieving sub-nanosecond synchronization. Experiments with 50 MHz New Radio signals at 3.2 GHz validate CJT performance under line-of-sight (LOS) and non-line-of-sight (NLOS) conditions. Results show up to 10.42 dB EVM-derived gain in the near-balanced LOS case and up to 6.22 dB relative improvement over the best contributing single-Tx baseline in the investigated NLOS cases.