MIMO-Supporting Radio-Over-Fiber System and its Application in mmWave-Based Indoor 5G Mobile Network

We demonstrate 4 × 4 multiple-input and multiple-output (MIMO) supporting mmWave-based indoor 5G mobile network based on a distributed antenna system (DAS) that has over-the-air interface to receive the broadband wireless signal from, e.g., remote radio head (RRH) of mobile fronthaul. To realize the cost/bandwidth-efficient and low-latency-inducing indoor 5G DAS network, we exploit the radio-over-fiber (RoF) system that is based on the intermediate frequency-over-fiber (IFoF) technology. To be more specific, we make simultaneous use of wavelength- and frequency-division multiplexing in the IFoF link so as to transport 4 × 4 MIMO 5G signal of which the bandwidth is effectively 3.2 GHz (= 4 × 800 MHz, where each antenna deals with 800 MHz 5G signal). The 4 × 4 MIMO-supporting IFoF link has error vector magnitude (EVM) performance of