Power control for relay-assisted cognitive radio networks-part I: Centralized scenario

Optimal power control for relay-assisted cognitive radio networks in which secondary users are assisted by cognitive relays is investigated. A monomial approximation based power control algorithm (MaPC) is developed to 1) maximize the secondary system weighted sum rates; 2) minimize the secondary system weighted sum powers under the individual and/or total power constraints of secondary users as well as the interference temperature limits of the primary users. The presented power control schemes are formulated using geometric programming and are then converted into equivalent convex optimization problems. Numerical results demonstrate the effectiveness of our proposed schemes.