Study on feasible solution of power control in cognitive radio networks

As one of the reconfigurable parameters in cognitive radio, transmit power has to be controlled in order to reduce the harmful interference and improve the signal quality. This paper investigates the optimal power control for secondary user in cognitive radio networks based on the achieved feasible solution. A feasible solution can be achieved if there is an existing nonnegative transmit power vector P ^* under constraint of the target Signal to Interference Ratio (SIR). Two topologies (fixed and random) are considered in observing the feasible solution for power control. The simulation results show that the distance between transmitter-receiver pair and number of nodes affect the feasible solution of the system, which is indicated by the maximum target SIR that is guaranteed from the optimal power control.