Adaptive Receiver for MCM Based NOMA in Doubly Selective Channels

Abstract

Non-orthogonal multiple access (NOMA) has been identified as a potential fundamental shift for the design of multiple access systems. Over a high Doubly Selective (DS) channel scenario, this paper considers the use of NOMA system based on Multi-Carrier Modulation (MCM) with various waveforms, with Orthogonal Frequency Division Multiplexing (OFDM) and Filter Bank Multicarrier Modulation (FBMC) as special cases. Furthermore, we investigate the Imperfect Successive Interference Cancellation (I-SIC). NOMA users are affected by intra-user interference and inter-user interference in this situation. To this end, an adaptive receiver scheme that combines one-tap equalization and a joint iterative interference cancellation, proposed in literature, is introduced. The receiver selects the appropriate data detection mechanism based on the power allocation factor and hence the channel constraints. The One-Tap equalizer is so useful in practice. Unfortunately, once the DS channel and NOMA induced interference begin to dominate the noise, a one-tap equalization under-performs. On the other hand, by using the joint iterative interference cancellation approach, performance will be greatly improved at the cost of computational complexity. Moreover, numerical simulations are carried out to illustrate the efficacy of the suggested combined strategy in contrast to the theoretical Perfect-SIC (PSIC) condition.