Fairness-aware hybrid NOMA/OFDMA for bandlimited multi-user VLC systems

In this paper, we for the first time propose and experimentally demonstrate a fairnessaware hybrid non-orthogonal multiple access/orthogonal frequency division multiple access (NOMA/OFDMA)scheme for practical bandlimited multi-user visible light communication (VLC) systems. The proposed fairness-aware hybrid NOMA/OFDMA scheme using discrete Fourier transform-spread-orthogonal frequency division multiplexing (DFT-S-OFDM) modulation can efficiently guarantee both the fairness of users within each user pair and the fairness of different user pairs. Specifically, an interleaved subcarrier multiplexing approach is proposed to mitigate user pair unfairness caused by the low-pass frequency response of bandlimited VLC systems, and a two-dimension (2D) power allocation strategy is further proposed to ensure both the fairness of users within each user pair and the fairness of user pairs with different channel conditions. Experimental results show that, in a bandlimited four-user VLC system applying the proposed fairness-aware hybrid NOMA/OFDMA scheme, the transmission distance at a target bit error rate (BER) of 3.8 x 10-3 can be extended by 12.3% in comparison to that employing the conventional hybrid NOMA/OFDMA scheme.