Power control schemes for spectrum sharing based on capacity conservation ratio in Rayleigh fading channel

In this paper, we propose novel criterion and novel power control schemes based on the capacity conservation ratio (CCR) by taking the Rayleigh fading effect into account using theoretical analysis. The CCR is defined as the ratio of the decreased capacity in the spectrum sharing to the original capacity of a system. We utilize the CCR as a novel metric for protecting a primary system (PS) from large capacity degradation. The proposed power control schemes based on CCR are divided into two kinds of power control scheme; an exact power control scheme and a simplified power control scheme. We analytically evaluate the performance of the simplified power control scheme and compare it with that of the other. We find that the simplified power control scheme offers sufficient PS protection performance without high computational cost.