Experimental Demonstration of Bidirectional OFDM/OQAM-MIMO Signal Over a Multicore Fiber System

A bidirectional transmission and massive multi-input multi-output (MIMO) enabled radio over a multicore fiber system with centralized optical carrier delivery is experimentally investigated in this paper. Optical carriers for upstream are delivered from the central office to the remote antenna unit via the inner core for the coreless implementation. In our experiment, as one of the fifth-generation (5G) waveform candidates, orthogonal frequency division multiplexing using offset quadrature amplitude modulation (OFDM/OQAM) is adopted in both uplink and downlink to increase the spectral efficiency and side lobes suppression ratio. An advanced 2 × 2 MIMO-OFDM/OQAM channel estimation algorithm is optimally designed to equalize the hybrid optical and wireless MIMO channels. The experimental results show that bidirectional transmission of 4.46 Gb/s 2 × 2 MIMO-OFDM/16-OQAM could be achieved over a 20-km seven-core fiber and a 0.4-m wireless link. The proposed scheme proves that the multicore fiber can realize the transparent transmission of bidirectional radio signals and effectively simplify the infrastructures in the future 5G cellular systems.