Power allocation with min-max fairness for cognitive radio networks

In this paper, we study power allocation strategies of the cognitive radio (CR) system. In a CR system the user has different channel condition. So, different amount of power resource is required to meets the QoS request. In order to guarantee the fairness of each CR user and limit the interference that is caused by other CR users within the range into the level that primary user can tolerate, we proposed two new power allocation schemes. The targets are to minimize the maximum power allocated to CR users, and to minimize the maximum outage probability over all CR users. The first power allocation scheme can be formulated using Geometric Programming (GP). Since GP problem is equivalent to the convex optimization problem, we can obtain the optimal solutions for the first scheme. The second power allocation is not a GP problem. We propose an iterative algorithm to solve it. Simulation results show that proposed schemes can efficiently guarantee the fairness of CR users under the QoS constraint of the primary user.