Wavelength Reuse in an RoF Link Based on CS-DSB, Coherent Detection and DSP

Wavelength reuse in a bidirectional radio over fiber link based on carrier-suppressed double-sideband (CS-DSB) modulation, coherent detection, and digital signal processing (DSP) is proposed and experimentally demonstrated. At the center office, an optical single-sideband with carrier (OSSB+C) signal is generated and distributed to the base station. The wavelength reuse at the base station is implemented by directly modulating the downstream OSSB+C signal with an upstream signal based on CS-DSB modulation. The modulated upstream signal is sent to the center office where a coherent receiver and a DSP unit are used to recover the upstream signal by eliminating the crosstalk from the downstream signal, and at the same time, to cancel the phase noise from the laser source. An experiment is performed. The transmission of a 16-QAM downstream microwave vector signal and a 16-QAM upstream microwave vector signal over a 17-km single-mode fiber (SMF) is experimentally demonstrated. The power penalty caused by the wavelength reuse is less than 0.8 dB.