Experimental Demonstration of a Novel Multi-User Bit and Power Loading Algorithm for OFDM-NOMA PON

In this article, we conduct an extensive investigation on our recently proposed greedy orthogonal frequency division multiplexing non-orthogonal multiple access (OFDM-NOMA) bit and power allocation (GONBP) algorithm, and further propose a novel margin-based OFDM-NOMA bit and power allocation (MONBP) algorithm for multi-user direct-detection (DD) OFDM-NOMA passive optical network (PON). Both algorithms allocate bits and power at both the user level and the subcarrier level by considering the frequency-selective fading effect of all users, the interaction/interference between users, and the constraint of total allocated bits for each user. 43-76 Gbit/s PON experiments where two optical network units have different transmission distances of 10–20 km and/or different received optical powers are performed. The results show that the proposed GONBP and MONBP outperform conventional OFDM-NOMA, discrete-Fourier-transform spread OFDM-NOMA, conventional greedy algorithm, and Chow's algorithm. Compared to GONBP, the proposed MONBP greatly reduces the complexity and achieves better performance especially when the signal-to-noise ratio profiles of ONUs are different, thus providing a promising solution for multi-user OFDM-NOMA PON.