Physical Layer Authentication over an OFDM Fading Wiretap Channel

Precise channel estimation at the physical layer allows to authenticate the source of a message in a wireless environment without the need of a pre-shared secret key based on the rapid spatial decorrelation of the channel. We consider the authentication scheme proposed by Xiao et al. and modify to suit a wiretap environment with orthogonal frequency division multiplexing (OFDM) modulation and fading channels. By formulating a nearly optimal attack strategy, and allowing some correlation among the channels, we evaluate the robustness of the scheme against challenging conditions and discuss the choice of system parameters.