Motivated by the primary user emulation attack in cognitive radios, this paper develops a physical layer user authentication scheme for wireless systems. The developed scheme consists of two stages: one-way hash function for generating authentication tags; physical layer tag embedding via controlled constellation perturbation. A detailed trade-off analysis is provided that balances the performance of the user authentication for the secondary user and symbol detection for the primary user.
In particular, we show that arbitrarily reliable user authentication can be achieved with an almost negligible performance degradation for the primary user under realistic system settings. Experimental results using the GNU Radio/USRP platform are provided to validate the proposed scheme.