LAUSR

This paper proposes a delta-orthogonal multiple access (D-OMA) scheme-based visible light communications (VLC) network to enhance spectral efficiency and massive connectivity in the indoor environment. The D-OMA scheme is an advanced version of the non-orthogonal multiple access (NOMA) scheme. D-OMA allows the partial overlapping of the in-band NOMA clusters to achieve the benefits of a massive in-band NOMA scheme with low power consumption and less complexity. In this work, the massive in-band NOMA scheme is used as a special case of the proposed D-OMA scheme. Game theory is employed for the user grouping mechanism, which enhances the sum rate of the proposed network. Closed-form expressions for the bit error rate (BER) and outage probability of the proposed network are derived. Further, downlink transmission power optimization is performed using Karush-Kuhn Tucker (KKT) conditions to improve the outage performance of the proposed D-OMA VLC network. The presented numerical results show the effect of optical filter gain and field of view (FoV) in indoor communication. Further, it is noted that the BER performance of the D-OMA scheme outperforms the massive in-band NOMA scheme due to the cluster sizes which control the interference in the D-OMA scheme. Moreover, the sum rate of the proposed network is significantly improved using the preference relation algorithm (PRA) compared to the random NOMA scheme.