Outage-Constrained Power Allocation in Spectrum Sharing Systems with Partial CSI

• Published in: IEEE transactions on communications Vol. 62; no. 2; pp. 452 - 466
• Main Authors: Xitao Gong, Ispas, Adrian, Dartmann, Guido, Ascheid, Gerd
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.02.2014; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Allocations; Applied sciences; Channel state information; Cognitive radio; Complexity theory; Detection, estimation, filtering, equalization, prediction; Exact sciences and technology; Fading; generalized Karush-Kuhn-Tucker conditions; Information, signal and communications theory; Interference; Mathematical analysis; Optimization; Outages; partial channel state information; performance analysis; power allocation; Power transmission; Radiocommunication specific techniques; Radiocommunications; Receivers; Resource management; Signal and communications theory; Signal, noise; Simplification; Strategy; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments); Transmitters. Receivers; Performance evaluation; Parameter estimation; Outage; Power transmission; Transmitter; Resource sharing; Cognitive radio; Power allocation; Addressing; partial channel state information; Relaxation; Optimal strategy; generalized Karush-Kuhn-Tucker conditions; Channel estimation; Optimal solution; Algorithm complexity; Convexity; Peak power; performance analysis; Software radio; Power spectrum
• ISSN: 0090-6778; 1558-0857
• DOI: 10.1109/TCOMM.2013.122113.120974

Due to limited cooperation between the primary users and the secondary users (SUs) in practical spectrum sharing systems, the secondary transmitters and receivers are assumed to have partial channel state information related to the primary receiver. Under such an assumption, this work investigates power allocation strategies for the SUs subject to an outage probability constraint on the primary transmission and a peak transmit power constraint on the secondary transmission. The challenge lies in the non-convexity of the outage probability constraint. Firstly, we prove that strong duality holds and that the Karush-Kuhn-Tucker (KKT) conditions are necessary for optimality. The optimal solution is then derived by addressing the optimality issues of the KKT solutions. Secondly, in order to further reduce the algorithmic complexity, two suboptimal strategies are proposed. The first one is designed based on several simplifications of the optimal strategy. The second one is derived from the convex relaxation of the non-convex primal problem, which corresponds to the problem with the conventional interference temperature constraint. The performance for both suboptimal strategies is derived in closed form. All proposed strategies are shown to outperform non-adaptive power transmission. The near-optimality of the two suboptimal strategies is also validated, in particular for the first one.