On the Secrecy Performance of Generalized User Selection for Interference-Limited Multiuser Wireless Networks

We investigate the secrecy performance of a multiuser diversity scheme for an interference-limited wireless network with a base-station (BS), N legitimate users and an eavesdropper, in the presence of a single dominant interferer. Assuming interference dominates noise power at the eavesdropper and at each legitimate user's receiver, the BS transmits information to the legitimate user with the k-th best (highest) signal-to-interference ratio. We derive a closed-form expression for the secrecy outage probability for an arbitrary N and an asymptotic expression for a fixed k and large N. Furthermore, we derive a closed form asymptotic expression for the ergodic secrecy capacity of the k-th best user and show that it scales like $O\left(\log(N)\right)$ for a fixed k and large N.