Using Artificial Noise to Improve Detection Performance For Wireless User Authentication in Time-Variant Channels

We consider a physical layer approach to enhance wireless security by using the unique wireless channel state information (CSI) of a legitimate user to authenticate subsequent transmissions (messages) from this user, thereby denying access to any spoofer whose CSI would significantly differ from that of the legitimate user by virtue of a different spatial location. In a recent solution one compares two random signal realizations representing the two messages via a binary hypothesis testing approach to ascertain whether they have identical power spectral densities. This solution is based on a time-invariant channel model leading to stationary random signals. In this letter we explore addition of artificial noise (AN) to the received signals in the two message frames in order to enhance performance under time-variant channels. We illustrate the proposed method via simulations and application to wireless user authentication.