The aim of this paper is performance analysis of the hybrid radio frequency (RF)/free-space optical (FSO) system, where the transmission is performed simultaneously over FSO link and spectrum sharing cognitive RF sub-system. The FSO link is affected by Gamma-Gamma atmospheric turbulence, while in spectrum sharing cognitive RF sub-system the peak interference power constraint at the primary user's receiver is considered in Nakagami-m fading environment. Outage probability expressions are provided in the integral form for the case when the maximal ratio combining (MRC) is applied at the destination. The effects of the atmospheric turbulence strength, the number of RF antennas, allowable power and fading severity on the outage performance are observed. Numerical results are presented and verified by Monte Carlo simulations
