Covert Communication Using Time Modulated Retrodirective Array.

In this letter, a novel covert communication strategy that utilizes a time modulated retrodirective array (TMRDA) is proposed to enhance communication covertness. Typically, beamforming (BF) is designed via employing cuckoo search (CS), in which the sidelobes are significantly suppressed. Then, the closed-form expression of covertness constraint is derived by considering the beam characteristic of TMRDA. On this basis, the block length and transmit power are further optimized to maximize the covert throughput. Our numerical results reveal the superiority of the proposed scheme over the existing covert communication strategies.