Joint Power-Domain and SCMA-Based NOMA System for Downlink in 5G and Beyond

In this letter, we propose a joint power and code-domain non-orthogonal multiple access (NOMA) technique for the fifth-generation (5G) wireless networks and beyond. We consider a downlink system, where the users' experience diverse channel conditions. The transmitter involves a sparse code multiple access (SCMA) encoder and allows diversity in power allocation to the users. The detection is based on combined message-passing and successive-interference-cancellation algorithms. Simulation results demonstrate that the proposed NOMA system achieves higher spectral efficiency than the conventional single power-domain NOMA- and SCMA-based systems.