On Interference Alignment Based NOMA for Downlink Multicell Transmissions

The upcoming wireless communication systems are expected to integrate a number of nodes remarkably greater than those observed in current technologies, while offering a sensibly improved service quality for critical applications. This generates a need for innovative schemes to share the available resources among the served terminals as well as to increase the system efficiency and node fairness. Aiming to this objective, we propose a combination of non-orthogonal multiple access and interference alignment schemes applied to the downlink transmissions in a multi-cell environment. The two methods presented in this work enable an efficient reutilization of resources and the suppression of intra-and inter-cell interference in a single step during signal reception. We derive the expressions for the feasibility of our proposed solution from an analysis applied to generic system configurations. Additionally, we show numerical results that highlight the benefits of this scheme in a system setup resembling an Internet-of-things scenario.