Applying Opportunistic Scheduling On Miso Wiretap Broadcast Channel

The problem of broadcasting secret information over wireless links under an secrecy constraint has recently been considered in this paper. The work was among the first to consider the impact of multiuser diversity on secrecy systems and proposed an opportunistic scheme that selects the user with the strongest channel at each time slot. In this work, we study the secrecy implications of opportunistic beamforming for the multiple-input single-output broadcast channel. Two opportunistic scheduling schemes exploiting multiuser diversity are investigated. It requires limited feedback of the effective signal-to-noise ratio (SNR) from the legitimate users. We derive new closed-form expressions for the ergodic secrecy rate with beamforming over which Rayleigh fading is considered for two scheduling schemes. The ergodic secrecy rate for two opportunistic scheduling polices 1) the user with maximal instantaneous channel quality is scheduled for communication, and 2) the proportional fair scheduling (PFS) approach are investigated. Iillustrate the impact of multiuser diversity on the secrecy performance in under information therotic perspective.