Physical Malicious Attacks Detection in AF Relaying Systems with Unreliable CSI

This paper deals with the detection of malicious attacks in a Gaussian two-hop relay network, in which the source transmits information to the destination with the assistance of an amplify and forward (AF) relay node with unreliable channel state information (CSI). We consider the case where the potentially malicious relay node attempts to corrupt the network by malicious forwarding. In addition, dishonest feedback results in reliable CSI is not available at the source and/or destination. By modeling the relay behavior with two kinds of operations, namely detectable and undetectable operations, we propose a novel detection method which can deal with any detectable malicious attacks and works effectively in the presence of unreliable CSI. For the detectable operation, it is shown that the malicious attacks can be, with high probability, successfully detected. Furthermore, our research has shown that, although for the undetectable operation each attack can fool the proposed detection method, these undetectable attacks do not affect the improvements cooperative diversity. The effectiveness of our method has been validated by numerical results obtained by means of computer simulations.