  Covert communication's effectiveness critically depends on precise channel
state information (CSI). This paper investigates the impact of imperfect CSI on
achievable covert communication performance in a two-hop relay system. Firstly,
we introduce a two-hop covert transmission scheme utilizing channel inversion
power control (CIPC) to manage opportunistic interference, eliminating the
receiver's self-interference. Given that CSI estimation error (CEE) and
feedback delay (FD) are the two primary factors leading to imperfect CSI, we
construct a comprehensive theoretical model to accurately characterize their
effects on CSI quality. With the aid of this model, we then derive closed-form
solutions for detection error probability (DEP) and covert rate (CR),
establishing an analytical framework to delineate the inherent relationship
between CEE, FD, and covert performance. Furthermore, to mitigate the adverse
effects of imperfect CSI on achievable covert performance, we investigate the
joint optimization of channel inversion power and data symbol length to
maximize CR under DEP constraints and propose an iterative alternating
algorithm to solve the bi-dimensional non-convex optimization problem. Finally,
extensive experimental results validate our theoretical framework and
illustrate the impact of imperfect CSI on achievable covert performance.
