A Power Domain Sparse Code Multiple Access Scheme for Visible Light Communications

We propose a non-orthogonal multiple access (NOMA) scheme known as power domain sparse code multiple access (PD-SCMA) for visible light communications (VLC), which uses both the power and code domains for multi users signal transmission. The signal model and the transceiver of PD-SCMA VLC are investigated. We show by experimental demonstration that, PD-SCMA is a promising multiple access solution for VLC systems offering higher achievable sum rate compared with other NOMA schemes. PD-SCMA with 2 power domain multiplexed layers offers twice the total data rate compared with SCMA at the cost of reduced transmission distance, which is not a problem for VLC systems as the transmission distance can be increased using higher power light sources, high-gain optical concentrators and advanced receivers