Secret information of wireless multi-dimensional Gaussian channels

Wireless channel reciprocity can be exploited by two users willing to achieve confidential communications over a public channel as a common source of randomness for the generation of a secret key. This paper presents an analytical framework for investigating the amount of secret information that characterizes wireless multi-dimensional Gaussian channels used as source of randomness. The intrinsic secrecy content of wide-sense stationary wireless channels in frequency, time and spatial domains is derived through asymptotic analysis. Some significant case studies are presented, where single and multiple antenna eavesdroppers are considered. In the numerical results, the role of signal-to-noise ratio, spatial correlation, frequency and time selectivity, sampling frequency and imperfect channel reciprocity is investigated.