Nonlinear Effects in NOMA Signals: Performance Evaluation and Receiver Design

Non-orthogonal multiple access (NOMA) is being considered a key technology for 5G systems. In this work, we consider power-domain NOMA schemes for downlink orthogonal frequency-division multiplexing (OFDM) transmissions. Moreover, we consider the use of an efficient, nonlinear power amplification. We analyze the nonlinear distortion effects associated with the power amplifier and show that the nonlinear distortion can be severe, preventing the use of conventional NOMA receivers. In that context, we propose a receiver that estimates and cancels the nonlinear distortion and enables the implementation of power-domain NOMA schemes in strongly nonlinear OFDM scenarios.