Non-Orthogonal Multiple Access (NOMA): Concept and Design

This chapter introduces the concept of non-orthogonal multiple access (NOMA) for both downlink and uplink channels, where it enables power-domain user multiplexing and the exploitation of the channel-gain difference among users in a cellular system, two features that were not exploited in current and past cellular systems. It also explains the interface-design aspects of NOMA, including multi-user scheduling and multi-user power control, and its combination with multiple-input, multiple-output (MIMO). For downlink NOMA, the chapter shows the link-level performance and system-level performance of NOMA combined with MIMO for OFDMA. For uplink NOMA, it presents a system-level performance comparison of NOMA with SC-frequency division multiple access (FDMA) and show the impact of fractional frequency reuse (FFR). The chapter provides the performance evaluation results based on computer simulations and the measurements obtained from the NOMA testbed. It presents NOMA testbed, the potential gains for both system-level and link-level simulations when NOMA is combined with SU-MIMO.