Introducing friendly jammer to unmanned aerial vehicle (UAV) covert communication could further enhance the covert performance. However, due to the additional communication overhead required for information synchronization (IS) among cooperating parties, the security risk is further elevated. It is noteworthy that cognitive jamming (CJ) could sense the cooperating node signals without IS links. Therefore, in this paper, we propose the cooperative UAVs covert communication scheme assisted by the CJ that maximize the minimum average covert rate (MACR). Specifically, the UAV (Alice) tries to transmit its private message to legitimate users under the surveillance of the Wardens. Since the Warden is in passive surveillance, the practical location uncertainty of the Warden is considered, and we further analyze the worst-case situation that derives the minimal detection error probability of the Wardens. Moreover, we maximize the MACR by alternatively optimizing the sense time ratio and trajectory of CJ, the transmit power and trajectory of the Alice. To expedite algorithmic convergence, we further introduce a principled initialization scheme. The simulation results reveal that the covert performance of the proposed algorithm outperforms the other schemes, especially, in the multi-warden scenario. Furthermore, compared with the full-time jammer and probabilistic jammer, the CJ can not only achieve a higher covert rate with less average jamming power, but also require no information synchronization link with Alice based on spectrum sensing, which promises considerable application prospects in real-world systems.

The integrated communication and jamming system can integrate communication and jamming functionalities to reinforce each other in one system, arising from the increasing demand for equipment miniaturization and resource multiplexing. This paper proposes the integrated communication and jamming network (ICAJN) where multi-functional nodes serve asmobileaccess points, providing flexible communication and jamming coverage in the temporary, infrastructure-less scenarios. In addition to coverage, connectivity is also essential to ensure distributed coordination and signalling interaction among nodes. However, achieving simultaneous coverage and connectivity is challenging due to two main factors: on one hand, there exists an inherent tradeoff between coverage and connectivity in terms of node deployment; on the other hand, the dynamic electromagnetic environment complicates the real-time link gain estimation. The goal of this paper is to incorporate environment-awareness capabilities into the ICAJN, dynamically adjusting the working state to achieve simultaneous coverage and connectivity. To this end, the workflow of the ICAJN is structured into an environment-awareness phase and an execution phase, and the event-triggered sensing protocol (ETSP) is introduced to activate sensing function on demand. In the environment-awareness phase, the spatial interpolation is developed to estimate the gains of wireless links in the yet-to-reach locations, and further infer communication/jamming coverage boundaries. In the execution phase, the working state optimization algorithm is proposed to determine optimal node deployment locations, transmit power, and grouping policies in the current environment. Extended simulation results demonstrate that incorporating environment-awareness capabilities into ICAJN can significantly improve the network performance. And the designed protocol shows adaptability to the dynamic electromagnetic environments.