Nonorthogonal multiple access for 5G

The basic idea of nonorthogonal multiple access (NOMA) is to support nonorthogonal resource allocation among the users at the ultimate cost of increased receiver complexity, which is required for separating the nonorthogonal signals. This chapter discusses the basic principles as well as the advantages of NOMA and the design principles and key features of dominant power-domain NOMA schemes in detail. It introduces dominant code-domain NOMA schemes in terms of their basic principles and key features and other NOMA schemes to present a thorough review of NOMA. The chapter addresses some performance evaluations and transmission experiments of NOMA, so as to verify the advantage of this new technology. NOMA solutions are considered as potentially promising 5G candidates. However, there are still numerous challenging problems to be solved. The chapter highlights the opportunities and future research trends of NOMA, in order to provide some insights into this promising field.