Relay selection with physical layer security for over-the-air computation

In this paper, we consider a physical layer security (PLS) issue in an amplify and forward (AF) relay assisted over-the-air computation (AirComp) network. The cooperative communication scenario is considered, which contains several sensor nodes and intermediate cooperative nodes, an eavesdropper and a fusion center (FC). The goal is to minimize the MSE at the FC within the constraints of safety performance. For secure communication, we introduce a relay selection approach. This method designates an intermediate node as a relay, which amplifies the received signal and forwards it to the Fusion Center (FC). Recognizing the non-convexity of the Mean Squared Error (MSE) minimization problem, making direct resolution challenging, we reformulate it into a difference-of-convex (DC) form. An iterative optimization algorithm is then employed for its solution. Simulation results demonstrate that our proposed scheme achieves superior computational performance compared to a benchmark method within a secure AirComp context.