Weighted sum rate optimization for cognitive radio MIMO broadcast channels

• Published in: IEEE transactions on wireless communications Vol. 8; no. 6; pp. 2950 - 2959
• Main Authors: Lan Zhang, Lan Zhang, Yan Xin, Yan Xin, Ying-chang Liang, Ying-chang Liang
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.06.2009; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Applied sciences; Beamforming; broadcast channel; Broadcasting; Channels; Chromium; Cognitive radio; Detection, estimation, filtering, equalization, prediction; Equivalence; Exact sciences and technology; Information, signal and communications theory; Interference; Interference constraints; Iterative algorithms; Maximization; MIMO; Optimization; power allocation; Power system modeling; Radio; Radio broadcasting; Radio transmitters; Radiocommunication specific techniques; Radiocommunications; Receiving antennas; Signal and communications theory; Signal, noise; Studies; sum rate maximization; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments); Transmitting antennas; Performance evaluation; MIMO system; broadcast channel; sum rate maximization; Transmission channel; Iterative method; Algorithm; Power allocation; Beam forming; Optimization; Beamforming; cognitive radio; Simulation; Optimal solution; Broadcast channels; MIMO; Radio communication; Software radio
• ISSN: 1536-1276; 1558-2248
• DOI: 10.1109/TWC.2009.080621

In this paper, we consider a cognitive radio (CR) network, in which the unlicensed (secondary) users are allowed to concurrently access the spectrum allocated to the licensed (primary) users provided that their interference to the primary users (PUs) satisfies certain constraints. We study a weighted sum rate maximization problem for the secondary user (SU) multiple input multiple output (MIMO) broadcast channel (BC), in which the SUs are subject to not only a sum power constraint but also interference power constraints. We transform this multiconstraint maximization problem into its equivalent form, which involves a single constraint with multiple auxiliary variables. Fixing these multiple auxiliary variables, we propose a duality result for the equivalent problem. Exploiting the duality result, we develop an efficient subgradient based iterative algorithm to solve the equivalent problem and show that the developed algorithm converges to a globally optimal solution. Simulation results are provided to corroborate the effectiveness of the proposed algorithm.