Recursive state estimation in relay channels with enhanced security against eavesdropping: An innovative encryption–decryption framework

Abstract

In this paper, the problem of secure recursive state estimation is addressed for a networked linear system over a relay channel. We consider the scenario where the transmitted signals and the internal state of the relay node might be intercepted by potential eavesdroppers. To prevent the system states from being inferred by potential eavesdroppers via overheard measurement signals, an encryption–decryption mechanism is adopted to protect the transmitted measurement signals over the communication links. Furthermore, for the purpose of preserving data privacy during the relaying process, a decryption-free relaying protocol is constructed, where a matrix-inequality-based method is proposed for the design of the desired parameters for the relaying protocol. Following this, a recursive state estimator is developed to generate state estimates through a set of recursions. Sufficient conditions are then derived to ensure the ultimate boundedness of the resultant estimation error variance matrix. Finally, the effectiveness of the proposed secure recursive state estimation scheme is demonstrated through a simulation example.