Uplink Performance of NOMA-2000 with Dynamic User Grouping

In some recent papers, the present authors revived an early non-orthogonal multiple access (NOMA) concept, which uses two sets of orthogonal signal waveforms and iterative interference cancellation. The beauty of this concept, which was introduced back in the year 2000, is that it fully avoids the power imbalance requirements of power-domain NOMA on which the current NOMA literature is heavily based. Using different type of receivers, these papers reported channel overload factors up to 25% on additive white Gaussian noise (AWGN) channels. In this paper, we investigate uplink performance on Rayleigh fading channels and we introduce a dynamic user grouping strategy, which leads to a substantial increase of the channel overload capability. Using this strategy, we show that the channel overload factor can be increased up to 100% at the expense of a virtually zero degradation of the signal-to-noise ratio (SNR).