A low complexity NOMA scheme in VLC systems using pulse modulations (invited paper)

Abstract

Successive interference cancellation (SIC) decoding scheme is commonly utilized in nonorthogonal multiple access (NOMA) scheme to obtain the data of each user under different channel conditions at acceptable complexity. However, the imperfect SIC would lead to error propagation (EP) problem, deteriorating the error performance of the NOMA scheme. In this work, a SIC-free NOMA scheme is proposed in the pulse modulation-based visible light communication (VLC) systems with two users. The user under worse channel condition adopts on-off keying (OOK) and the other employs multiple pulse position modulation (MPPM). Here, we employ the soft decision decoding (SDD) scheme to decode the MPPM signal of the user under the better channel condition, which could fundamentally alleviate the adverse impact of EP on symbol error rate (SER) performance and is easier and faster to implement than the traditional SIC decoding scheme. The expressions of SER for two users are derived and the Monte Carlo (MC) simulation results are further provided to validate analytical results.