Covert Communications for Energy Harvesting NOMA Systems

This paper investigates covert communication in energy harvesting (EH) non-orthogonal multiple access (NOMA) systems. Specifically, the EH source employs the NOMA protocol to simultaneously transmit information to both public and covert users under warden surveillance. We first derive the analytical expressions for the warden’s detection error probability (DEP) and the outage probabilities of the two NOMA users. In addition, the closed-form optimal detection threshold that minimizes the DEP from the warden’s perspective is obtained. An optimization problem is formulated to maximize the effective covert rate subject to both covertness and outage probability constraints. Finally, the theoretical derivations are verified through Monte Carlo simulations.