Multi-User Physical-Layer Authentication and Classification

This paper concerns the problem of authenticating different transmitters at the physical layer in a multi-user scenario. In this paper, we propose two tag-based Physical-Layer Authentication (PLA) schemes in a multi-user scenario. We name the first scheme as the Multi-User Physical Layer Authentication and Classification (MU-PLAC) scheme, which not only detects an impersonation attack but also achieves multi-user classification. For further improving the performance of the MU-PLAC scheme for a two-user scenario, we propose an enhanced version of the MU-PLAC scheme by elaborately designing the tags of two legitimate users. We name the second scheme as the Enhanced Multi-User Physical Layer Authentication and Classification (EMU-PLAC) scheme. We provide the theoretical analysis of the proposed schemes over wireless fading channels and derive their closed-form expressions. We implement the proposed schemes and conduct extensive performance comparisons. Our simulation results show that, for a two-user scenario, the EMU-PLAC scheme provides better classification accuracy and authentication accuracy as compared with the MU-PLAC scheme.