Robust Power Control Algorithm for Multiple Primary Users and Secondary Users in Cognitive Radio Networks

Guanglong Yang, Xiao Wang, Xuezhi Tan
2014 International Journal of Control and Automation  
Conventional distributed power control algorithms in cognitive radio (CR) are based on the assumption of perfect channel state information (CSI) which may lead to performance degradation in practical systems. In this paper, the robust distributed power control problem is investigated in CR systems by considering the uncertainty of channel gain. The objective is to maximize the sum rate of secondary users (SUs) subject to the primary users (PUs) interference power constraints and the
more » ... and the transmission power constraint of SUs. The channel gain fluctuation is described using ellipsoid sets and the interference power constraints can be converted into robust interference power constraints. Lagrangian duality method is applied to solve the robust power control problem in a distributed way. Simulation results show that the effectiveness of the proposed robust algorithm. 76 Copyright ⓒ 2014 SERSC uncertain. In [10], the authors studied the problem of joint beamforming and power allocation in a cognitive MIMO system using game theory, in this work the imperfect CSI was taken into account by the robust interference constraint. The optimization problem in the formulated robust game is converted into a SOCP problem. Comparing with previous work on robust power control in CR, in this paper, we study the problem of power control in cognitive downlink where multiple SUs coexisting with multiple PUs. The aim is to maximize the sum rate of SUs under the interference power constraints at PUs, the total transmission power constraint of SUs. An ellipsoid model was adopted to describe the CSI uncertainty and the objective function can be transformed to a concave function through a log transformation. Moreover, a subgradient iteration algorithm is proposed. Simulation results show that the effectiveness of the proposed robust algorithm. The rest of this paper is organized as follows. In Section 2, the system mode of CR is introduced and the robust power control problem is formulated. In Section 3, the objective function is transformed to a concave function through a log transformation and a subgradient iteration algorithm is proposed. Numerical results are presented in Section 4. Concluding remarks are made in Section 5.
doi:10.14257/ijca.2014.7.11.08 fatcat:it3zcmnsijf5llnqa5lc5bb7ga