Non‐orthogonal multiple access without channel state information for similar channel conditions

Abstract

A downlink non-orthogonal multiple access with QPSK input constellations based on virtual channel optimisation is presented to address the similar channel conditions scenario. The novel idea is to construct a uniquely decodable sum constellation by maximising the minimum Euclidean distance among the points of the superposed constellation. An optimal angle difference is derived to make the proposed scheme easy to implement. With a fixed angle pair setup, a non-orthogonal multiple access system without the knowledge of channel state information is proposed. Simulation results are provided to demonstrate the performance of the proposed scheme.