<p>Aiming at the typical scenario where a base station transmits public data to a far user with the help of a near user, a covert communication transmission scheme between far and near users is proposed under the cover of the base station’s public signals. In this scheme, a dynamic power control strategy for the far user is proposed, that is, the transmission power of covert data is adjusted according to the real-time eavesdropping channel state information (CSI) to realize the intelligent regulation of covert transmission. The near users combine physical-layer network coding (PNC) with non-orthogonal multiple access (NOMA) technology, that is, the secret data of the far user is jointly processed with its own secret data and the base station’s public data by bit-level XOR operation, and then forwarded by power superposition technology. The detection error probability (DEP), the optimal detection threshold, and the corresponding minimum DEP of the system under this strategy are derived, and the closed-form expressions of outage probability (OP) and intercept probability (IP) are obtained, and the theoretical achievable performance limits of OP and IP under the condition of high signal-to-noise ratio (SNR) are further given. Finally, the simulation results show that the proposed scheme is significantly superior to the traditional power control strategy in covert performance, security, and reliability, and the influence law of related parameters on the system performance is consistent with the theoretical derivation results, which verifies the superiority of the proposed strategy in complex eavesdropping environments.</p>