Multilevel Modulations for Gigabit Access in a Simple Millimeter-Wave Radio-Over-Fiber Link

A spectrally efficient and simplified full-duplex millimeter-wave (mm-wave) radio-over-fiber (RoF) link is proposed and experimentally demonstrated. For downlink, a multilevel amplitude-shift-keying (M-ASK) modulation, such as 4-ASK, for a total data rate of 5 Gb/s, is applied on two uncorrelated optical carriers at the central station (CS) for remote heterodyning at the photodetector. The mm-wave signal generated through the photodetection process is then self-homodyned at the mm-wave receiver to recover the desired 4-ASK data. For uplink, an RF self-homodyning technique is applied again to retrieve the 4-ASK 5-Gb/s data at the base station before being transported to the CS as a simpler baseband-over-fiber transmission. While the actual generation, transport, and data recovery remain simplified for the proposed mm-wave RoF link, M-ASK implementation in such a system provides a spectrally efficient and simplified scheme which supports higher data rates.