5G Non-Orthogonal Multiple Access Study in 3GPP

As a key technology for 5G, non-orthogonal multiple access (NOMA) can improve system capacity and connection densities. In this article, Release 16 study on NOMA in 3GPP is overviewed, which encompasses the transmitter side processing, receiver types and complexity, channel structure, and performance evaluations. Compared to the technical report of the NOMA study item, this article also highlights the relevant use cases and explains the performance relationship between link and system levels. In addition, the article touches some fundamental theory as well as very practical engineering. The aim is to provide readers a comprehensive picture of the technical essence of the NOMA study item, with insight into how to balance between cost, complexity, performance, and analytical pursuit. Some future directions are also provided.