Robust Resource Allocation for Symbiotic Radio Systems With Imperfect CSI and Eavesdropper

Symbiotic radio is a new communication paradigm for improving spectrum efficiency and system capacity. However, most of the existing resource allocation algorithms do not consider the impact of channel estimation errors and information leakage. To improve transmission security and robustness, in this paper, we investigate a robust secure resource allocation problem for a downlink multiuser symbiotic radio network with imperfect channel station information (CSI) and eavesdroppers. Based on bounded CSI error models, the overall throughput is maximized subject to the secure rate constraints, the maximum transmit power constraint, the time allocation constraint, and the reflection coefficient constraints. Moreover, the worst-case approach, the variable substitution approach, and Lagrange dual theory are applied to convert the originally non-convex problem into a convex one, where the closed-form solutions are solved by using the subgradient method. Simulation results verify the proposed algorithm has higher satisfaction probabilities and secure transmission rates.