Transmitter Design for Downlink Non-Orthogonal Multiple Access System in Frequency-Selective Channels

In this paper, we propose design methods of timedomain filters at a base station for downlink non-orthogonal multiple access in frequency-selective channels. The filters are determined by solving a signal-to-noise-plus-interference ratio maximization problem under a constraint on intersymbol interference suppression. Furthermore, we propose a power allocation method that maximizes the sum-capacity. Simulation results are provided to show the effectiveness of the proposed method and the superiority to a conventional orthogonal multiple access system.