Sub-Carrier-Multiplexed Duplex 64-QAM Radio-over-Fiber Transmission for Distributed Antennas

We demonstrate the feasibility of Radio Over Fiber (ROF) transmission of 4 Sub-Carrier Multiplexed (SCM) 64-QAM data streams to a pair of low-complexity Radio Access Units (RAUs), which form part of a virtual MIMO architecture under the control of a Central Unit (CU). The ROF signal is transmitted over low frequency RF carriers and heterodyne detection is used at the RAUs. The 4 coherent optical carriers used for data transmission as well as for heterodyning at the RAUs are generated using a single laser rather than several inevitably non-coherent lasers. Our proposed system transmits duplex data of 480 Mbit/s and 240 Mbit/s in the downlink and uplink directions, respectively at mm-wave frequencies of 25 GHz or 50 GHz.