Performance Analysis of Mean Value-Based Power Allocation with Primary   User Interference in Spectrum Sharing Systems
  In this paper, we provide an exact expression for the ergodic capacity of the secondary user, and a unified closed-form expression for its bounds with taking the consideration of the primary interference at the secondary receiver. In addition, a simple but accurate approximation of the the ergodic capacity of the primary user is presented. Moreover, a primary user capacity loss based power allocation scheme for the secondary user is also proposed. Finally, we compare the performance of the two power allocation schemes in terms of the sum capacity. The results are validated through using numerical results and simulations. 
Ruifeng Duan, Riku J\"antti, and Mohammed S. Elmusrati
cs.IT math.IT