Experimental comparison of FBMC and OFDM for multiple access uplink PON

Filter bank multicarrier (FBMC) is a favourable candidate for next generation optical access networks due to its capability to operate without a cyclic prefix and its high resilience to synchronization errors in the system. In this paper, we analyze the performance of FBMC in upstream passive optical networks (PON), without the employment of inter optical network unit (inter-ONU) frequency guard bands. By using both experimental work and numerical simulations, the impact of relative time offsets on inter-ONU orthogonality is studied. Furthermore, numerical simulations are also used to study the impact of frequency offsets in such systems. Moreover, comparisons are drawn to orthogonal frequency division multiplexing (OFDM)-based upstream PONs. This paper experimentally demonstrates that imperfect time synchronization impacts all subcarriers in an OFDM system, while it affects only the immediately adjacent subcarriers in an FBMC system, which could be corrected for by the restoration of synchronicity between users. A simple feedback mechanism is experimentally demonstrated to automatically restore orthogonality and synchronization between users in order to validate the practical implementation of the scheme.