Spectral-Efficient Downlink Systems under Imperfect SIC and CSI: MC-NOMA or Partial NOMA?

This letter investigates a scalable hybrid non-orthogonal multiple access (NOMA) scheme termed partial NOMA (pNOMA) based on the partial sharing of the frequency resources among the users. In particular, we aim to design a spectrally-efficient multi-user downlink scheme under imperfect successive interference cancellation (SIC) and channel state information (CSI) via a joint control on the power allocation and bandwidth overlap for all users. In particular, we formulate the joint optimization problem of the power allocation for each user and channel allocation for overlapped and non-overlapped signals and later solve it using a meta-heuristic search-based differential evolution algorithm. Simulation results validate that the considered pNOMA scheme flexibly integrates OMA and multi-channel NOMA schemes, and outperforms them in terms of the sum rate under stochastic imperfection in SIC and CSI.