Defeating Jamming Attacks in Downlink Pairwise NOMA Using Relaying

This study explores an incremental relaying strategy in downlink pairwise Non-Orthogonal Multiple Access (NOMA), which involves multiple pairs of nodes near and far from the downlink destinations. The strategy aims to select a near destination node to relay the packet of a far destination node, considering the presence of jamming attacks. To this end, we first derive closed-form expressions for the individual outage probability (IOP) for both near and far destinations in Nakagami-m fading channels. Next, the overall IOP (OIOP) performance is defined as the maximum value among the obtained IOPs, ensuring fairness among the nodes. To optimize the system, simulated annealing algorithms are proposed to determine the best power allocation and the best relay-destination pairing. We can conclude that both the power allocation and the position/selection of the near destination node significantly impact the OIOP for a specific pair. However, in the case of multiple pairs of destinations, a good power allocation alone suffices for each pair, and fixed or even random destination pairing is satisfactory in the considered context.