Hybrid PD-NOMA and SCMA Scheme for massive Machine Type Communication

Abstract

Massive machine type communication (mMTC) has emerged as a key driver for societal digitalization, promising connectivity to a vast number of devices, reaching up to 10M/km2. However, conventional cellular systems struggle to efficiently handle the massive influx of short packet transmissions inherent to mMTC. Non-Orthogonal Multiple Access (NOMA) presents a promising solution by allowing multiple users to share the same resources. This paper explores the integration of Power-Domain NOMA (PDNOMA) and Sparse Code Multiple Access (SCMA) to superimpose extra users having different quality of service requirements, on the SCMA multiplexed signal in a spectrally efficient manner. The proposed hybrid system demonstrates increased spectral efficiency, enhanced overloading capability, reduced receiver complexity as compared to traditional NOMA and SCMA systems.