Relay authentication by exploiting I/Q imbalance in amplify-and-forward system

Although cooperative relaying has been widely utilized in wireless communications, it simultaneously introduces a new source of security vulnerabilities to the wireless networks such as denial of service attacks. In order to minimize the potential security risks from relays, reliable relay authentication schemes become necessitated. In this paper, a novel relay authentication scheme is proposed to secure amplify-and-forward relay systems through utilizing the device-dependent hardware imperfection in-phase/quadrature (I/Q) imbalance. In this scheme, the I/Q imbalance associated with the receiving and transmission of the relaying process is considered as a unique device fingerprint. This fingerprint is then utilized to develop a two-parameter hypothesis testing based authentication. To enhance the performance in differentiating delicate difference between I/Q imbalances, the generalized likelihood ratio test for classical linear model is used in our hypothesis decision algorithm. The performance of the proposed authentication scheme is assessed and validated by numerical simulations. The results show significantly enhanced authentication accuracy of our new method in comparison with other I/Q imbalance based hypothesis decision algorithms.