On the BER performance of QoS-aware multi-user OWC uplink using mCAP-NOMA

In this paper, we propose and investigate a hybrid multi-band carrierless amplitude and phase modulation and non-orthogonal multiple access (mCAP-NOMA) scheme for quality-of-service (QoS)-aware uplink multi-user optical wireless communication (OWC) systems. Considering the users' distinctive channel conditions and QoS requirements, we further design three user pairing approaches for the mCAP-NOMA-based uplink OWC system, including channel gain-based user pairing, modulation order-based user pairing and adaptive user pairing. More specifically, the adaptive user pairing approach can dynamically select from the individual channel gain-based or modulation order-based user pairing approaches aiming to obtain a lower average bit error rate (BER) of the uplink OWC system. Simulation results verify the feasibility and superiority of the mCAP-NOMA scheme with adaptive user pairing in an uplink four-user OWC system.