Physical Layer Security in Ultra-Dense Networks.

We study the physical layer security in ultra-dense networks considering the close proximity of the users to the cells. In particular, we show the effect of the small cells' density, the users' density and the eavesdroppers' density on the average secrecy rate. To this end, stochastic geometry is employed in order to provide tractable expressions for the average secrecy rate where Rician fading channels are considered in the main and the leakage links. The accuracy of the derived analytical expressions is confirmed by simulations.