Adaptively Modulated OFDM RoF Signals at 60 GHz Over Long-Reach 100-km Transmission Systems Employing Phase Noise Suppression

We experimentally demonstrated the transmission performance of orthogonal frequency-division-multiplexing (OFDM) signals in a 60-GHz radio-over-fiber system over up to 100-km standard single-mode fiber employing an adaptive bit-loading algorithm. Considering dispersion-induced phase noise, the maximum capacities after different fiber distances are investigated with and without a phase noise suppression (PNS) algorithm for the first time. When a distributed-feedback (DFB) laser with the linewidth of 1.3~4.1 MHz is modulated to carry the radio signals, the PN will result in more than 21.5% capacity decrease after 100-km fiber and 3-m wireless link, and the PNS algorithm which needs no bandwidth-consuming pilot tones can accomplish more than 15.3% capacity increase.