Single and Multiple Carrier Designs for Cognitive Radio Systems

In this paper, we study design problems for single and multiple-carrier Multiple-Input Multiple-Output (MIMO) Cognitive Radio (CR) systems. We assume imperfect Channel State Information (CSI) of the channels between the Secondary Users (SUs) and the Primary Users (PUs) at the SUs and propose solutions based on a Linear Matrix Inequality transformation that facilitates proper treatment of channel uncertainty at the SU transmitter. We employ convex optimization tools and use a Lagrange dual decomposition approach to solve the optimization problems efficiently. We also present a number of numerical results which clearly demonstrate the robustness and importance of the proposed algorithms.