Scalar Superposed Coded Modulation in the Multiple-Input-Single-Output Visible Light Communication System

Superposed coded modulation (SCM) can provide considerable diversity coding gain in the multiple-input-single-output (MISO) visible light communication (VLC) system. In this paper, we proposed a new concept of SCM scheme at the overall spectrum efficiency (SE) of 5 bit/Hz, which is named as scalar SCM (S-SCM). S-SCM overcomes the defect that PAM based SCM cannot be applied to odd-order signals. Furthermore, two novel S-SCM schemes which are based on probabilistic constellation shaping (PCS) pulse amplitude modulation (PAM) and uniform quadrature amplitude modulation (QAM) are addressed in this publication, respectively. Compared to the performance of the two-dimension SCM (2D-SCM) schemes, experimental results proved that the S-SCM is superior to the 2D-SCM, whose operation range is at most 2.88 times that of 2D-SCM when adjusting the power ratio between two transmitters. Furthermore, S-SCM measured a transmission rate of 2.385 Gbps below the 3.8×10⁻³ forward error correction (FEC) threshold, which is the highest data rate in the MISO-VLC system to the best of our knowledge.