Design of WDM-RoF-PON for Wireless and Wire-Line Access With Source-Free ONUs

In this paper, we design a wavelength-division-multiplexed radio-over-fiber passive optical network (WDM-RoF-PON) based on polarization multiplexing (PM) and carrier-suppressed return-to-zero quadrature differential-phase-shift keying (CSRZ-QDPSK) that can achieve wire-line and wireless access synchronously. Using PM and QDPSK modulation, the system improves bandwidth utilization. The key new feature of the approach is source-free optical network units (ONUs) including wireless access and upstream communication. By use of a reflective semiconductor optical amplifier and the reuse of the downstream light source, the ONU can omit the laser source and makes the WDM-PON colorless. This networking has the credible transmission property, including wireless access and fiber transmission. It also has a large coverage area.