Experimental demonstration of upstream transmission in digital filter multiple access pons with real-time reconfigurable optical network units

Digital filter multiple access (DFMA) passive optical networks (PONs) exploit centralized softwaredefined networking (SDN) controller-managed and transceiver-embedded digital orthogonal filters in individual optical network units (ONUs) to enable end-users to adaptively and dynamically access and share a common fiber transmission medium. DFMA PONs have the potential of not only equipping NG-PONs with sufficient network operation flexibility, adaptability, elasticity, and reconfigurability, but also providing highly desirable backward compatibility with current PON standards. In this paper, for the first time to our knowledge, multipoint-to-point upstream signal transmission in intensity-modulation and direct-detection (IMDD)DFMAPONs is experimentally demonstrated using two real-time, reconfigurable, optical orthogonal frequency division multiplexing-modulated ONUs and an offline optical line terminal. The experimental demonstrations show that each ONU achieves a similar upstreambit error rate performance, excellent tolerance to inter-ONU sample timing offset, and a relatively large ONU launch power variation range.