Rate Optimization for Integrated Energy-Harvesting, Sensing and Covert Communication Systems

The rapid development of uncrewed aerial vehicle (UAV) technology has brought security threats, which has motivated the development of integrated sensing and communication (ISAC) systems to address these issues. However, the power supply limitations of distributed ISAC nodes and the demand for covert signal transmission in adversarial scenarios remain unresolved. This paper focuses on covert transmission optimization for an integrated energy-harvesting, sensing and covert communication (IEHSCC) system, consisting of energy-harvesting (EH) nodes with switchable sensing/jamming modes and an ISAC base station (BS) to avoid detection by adversarial warden Willie. The minimum detection error probability (DEP) of Willie is derived, and the IEHSCC system’s sensing and covert transmission performance are calculated. Concerning the channel state information (CSI) estimation error, a joint optimization problem for EH node beamforming, BS beamforming, power allocation and EH node mode selection to maximize covert transmission rate is formulated. The problem is decomposed into subproblems and solved via S-Procedure and semi-definite relaxation (SDR) algorithm. An iterative water-filling algorithm is proposed to select EH modes. Simulation results show the proposed algorithm achieves fast convergence and effectively improves the covert transmission rate in the IEHSCC system. Increasing the number of antennas of EH node can increase covert rate, while excessive nodes or BS power degrades system performance, requiring rational configuration in practice.