Demonstration of Real-Time Software Reconfigurable Dynamic Power-and-Subcarrier Allocation Scheme for OFDM-NOMA-Based Multi-User Visible Light Communications

We propose and demonstrate a real-time software reconfigurable dynamic power-and-subcarrier allocation scheme for orthogonal frequency division multiplexing based non-orthogonal multiple access (OFDM-NOMA) in visible light communications (VLC) systems. The key digital signal processing algorithms for real-time OFDM-NOMA implementations are illustrated in details. With the help of the software reconfigurable technique, the power ratios of different sub-bands can be dynamically adjusted according to the channel conditions, resulting in superior user fairness and optimal transmission performance. Moreover, the subcarrier number of each user can also be flexibly controlled to fulfill the corresponding capacity demands. To validate the effectiveness of the proposed scheme, we consider different user scenarios with various path losses for extensive performance evaluations. Experimental results show that 1.84-Gbit/s real-time OFDM-NOMA transmission can achieve stable operation over several hours, wherein the BER is below the hard-decision forward error correction threshold of 3.8×10
^-3
. The proposed scheme provides a promising solution for practical implementations of multi-user VLC, as it is markedly adaptive to dynamic capacity demands while maintaining better user fairness and system flexibility and stability.