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To prevent detection of communication between legitimate users by warden and guarantee a strong security in wireless networks, covert communication technique is recommended. The covert communication is based on hiding the main message in the background of noise which poses challenges such as low transmission rate. On the other hand, the transmit power in the conventional networks is supplied by separate built-in batteries, which are sometimes hard to be recharged or replaced especially in the military applications. In this work, to tackle the low transmission rate, we employ three dimensions beamforming in which we can focus the main beam on the legitimate user and minimize the leakage information at the warden. Moreover, in the proposed network, we intend to employ cooperative jamming (CJ) to increase covert rat in which the jammer is equipped to multiple antennas. Furthermore, to tackle the recharging or replacing batteries in the proposed network, we employ the energy harvesting (EH) technique. The simulation results reveal that the energy harvesting from the jammer's signal reduce the total power consumption. Moreover, the simulation results show that the optimality gap is about 50% according to energy harvesting technique, and the 3D beamforming increases covert rate about 70% compared to two-dimensional beamforming method. [ABSTRACT FROM AUTHOR]

Covert communication is often limited in rate because it is difficult to hide the signal in the background noise. Recent work has shown that jamming can significantly improve the rate at which covert communication can be conducted, but this jamming signal has a devastating effect on the receiver. To tackle this issue, we equip the jammer with multiple antennas so that it can employ beamforming to place the intended receiver in the null space of the jamming. Moreover, in order to increase rate in this network, we equip the transmitter with an antenna array to be able to perform 3-dimensional (3D) beamforming toward its intended recipient. To evaluate this design, we formulate an optimization problem and present an iterative algorithm to solve it. Moreover, since Willie is passive, it is possible that Alice is not able to estimate the location of Willie perfectly. Hence, we investigate a new practical scenario in which the information about Willie's location is imperfect at Alice. Numerical results consider both the rate of covert communication with the proposed architecture and the gap between the result from our optimization and that obtained from exhaustive search. Numerical results highlight that the optimality gap is on average approximately 10%, and 3D beamforming compared to 2D beamforming increases covert rate by approximately 70%. [ABSTRACT FROM AUTHOR]