Covert Transaction for Cognitive Integrated Satellite Aerial Ground Networks With NOMA and Imperfect Limitations

Covert transaction (CT) is a popular topic investigated in recent years. In this research, we study the CT of the integrated satellite aerial ground networks (ISAGNs). Particularly, to optimize spectrum efficiency and resource utilization, cognitive technology and the non-orthogonal multiple access (NOMA) scheme are employed in the ISAGNs to improve the system’s covert performance. Besides, to reflect real-world scenarios, the imperfect hardware, imperfect channel estimation, and the co-channel interferences are also investigated for the ISAGNs. Moreover, to reduce system complexity, the decode-and-forward scheme is implemented in the aerial relay to transmit the covert signal. In addition, a newly defined detection error probability (DEP) is proposed for the CT of the system under consideration. Furthermore, by taking these factors into account, the closed-form expressions for the DEP, outage probability (OP), and covert transmission rate (CTR) are also obtained. Finally, several representative Monte Carlo simulations are conducted to evaluate the impacts of system and channel parameters on the covert system performance.