A NOMA Scheme for IoT Enabled by Selective Powering of Passive Backscattering Nodes

In this letter, we propose a novel communication strategy for Non-orthogonal Multiple Access (NOMA) systems with passive backscattering sensor nodes. The proposed scheme relies on the ability to control the number of backscattering sensors contending the channel, by tuning the transmission power of the illuminator incrementally. Multiple-access interference is then mitigated by Successive Interference Cancellation (SIC) at the receiver. To benchmark the performance of our proposal, a random access NOMA scheme is considered. We show that our proposal outperforms the random access protocol in terms of average spectral efficiency, while guaranteeing a substantial reduction in the energy consumption.