An apparatus and a method for joint power control in a wireless communication system are provided, in which customer premise equipments to be serviced are selected by scheduling, upon receipt of service requests from the customer premise equipments, the interference level of each of the selected customer premise equipments that affects an incumbent system is calculated, a total interference level affecting the incumbent system is calculated by summing the interference levels of the selected customer premise equipments, and a transmit power of the each customer premise equipment is reduced, if the total interference level is larger than a threshold.