Outage Performance of Spectrum Sharing Systems with MRC Diversity under Multiple Primary User´s Interference

In this letter, we investigate the impact of interference from multiple primary transmitters (PTs) on the outage performance of spectrum sharing systems with maximal ratio combining (MRC) diversity at the secondary receiver (SR) in Rayleigh fading channels. In particular, an exact closed-form expression for the outage probability is derived, which provides an efficient means to evaluate the joint effects of key system parameters, such as the number of antennas at the SR, the number of PTs and primary receivers (PRs), the maximum secondary transmit power, the interference temperature constraints at the PRs, and the primary interference powers at the SR. In addition, the asymptotic behavior of the outage probability is investigated, which reveals that the secondary system exhibits the outage saturation phenomenon and zero diversity gain. Simulation results demonstrate that a stringent interference temperature constraint has a significant detrimental effect on the outage probability, which could, however, be substantially alleviated by increasing the number of SR antennas.