Signal-to-Noise Ratio Considerations for Secure Antenna Polarization Modulation

We investigate the impact of additive white Gaussian noise on the performance of secure antenna polarization modulation (SAPM), a technique for wireless physical layer security. The secrecy rate, calculated from the mutual information of intended versus eavesdropper channels, serves as a metric for evaluation. With increasing signal-to-noise ratio (SNR), system designers can also choose to increase spectral efficiency by using a higher order of modulation. This significantly improves the level of security provided by SAPM by narrowing the range of spatial angles for which information may be received. We use simulation data to calculate the mutual information and symbol error probability over varying SNR levels to illustrate these effects.