The nonorthogonal multiple access (NOMA) is one of the fledging paradigms that the next generation radio access technologies sprouting toward. The NOMA with superposition coding (SC) in the transmitter and successive interference cancelation (SIC) at the receiver comes with many desirable features and benefits over orthogonal multiple access such as orthogonal frequency division multiple access adopted by long-term evolution. Various studies reveal that the NOMA is a noble spectrum-efficient technique, which can also be designed in the light of energy efficiency. In this chapter, we study the recent progresses of NOMA in fifth-generation (5G) systems. We discuss the basic concepts of NOMA and explain its aspects of importance for future radio access. Then, we provide a survey of the state of the art in NOMA solutions for 5G systems with numerical performances and provide some avenues for future research on NOMA on a set of open issues and challenges.

Chapter Contents:

• 1.1 Introduction
• 1.2 Basic concepts of NOMA
• 1.2.1 Superposition coding
• 1.2.2 Successive interference cancelation
• 1.2.3 A typical NOMA scheme
• 1.3 Potential NOMA solutions
• 1.3.1 NOMA performances in 5G
• 1.3.2 Cooperative NOMA
• 1.3.3 Fairness in NOMA
• 1.3.4 NOMA with beamforming
• 1.3.5 NOMA in coordinated system
• 1.3.6 Network NOMA
• 1.3.7 NOMA in MIMO systems
• 1.3.8 Energy-efficient NOMA
• 1.3.9 Other NOMA solutions
• 1.3.9.1 NOMA in light communication
• 1.3.9.2 NOMA with Raptors codes
• 1.3.9.3 NOMA with network coding
• 1.3.9.4 Coexistence of NOMA and OMA
• 1.4 NOMA challenges
• 1.4.1 Distortion analysis
• 1.4.2 Interference analysis
• 1.4.3 Resource allocation
• 1.4.4 Heterogeneous networks
• 1.4.5 Beamforming outage
• 1.4.6 Practical channel model
• 1.4.7 Uniform fairness
• 1.4.8 Other challenges
• 1.5 NOMA implementation issues
• 1.5.1 Decoding complexity
• 1.5.2 Error propagation
• 1.5.3 Quantization error
• 1.5.4 Power allocation complexity
• 1.5.5 Signaling and processing overhead
• References

Inspec keywords: interference suppression; 4G mobile communication; multi-access systems; encoding

Other keywords: next generation radio access technology; superposition coding; orthogonal multiple access; Long-Term Evolution; receiver; successive interference cancellation; spectrum-efficient technique; energy efficiency; SIC; transmitter; 5G green mobile networks; nonorthogonal multiple access scheme; NOMA schemes; orthogonal frequency division multiple access; fifth-generation systems

Subjects: Multiple access communication; Codes; Electromagnetic compatibility and interference; Mobile radio systems