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Journal of Optimization
Volume 2014, Article ID 190196, 13 pages
http://dx.doi.org/10.1155/2014/190196
Research Article

Optimal and Suboptimal Resource Allocation in MIMO Cooperative Cognitive Radio Networks

1Electrical Engineering Department, University of Zanjan, Zanjan 45371-38791, Iran
2Electrical Engineering Department, University of Tehran, Tehran 24785-54789, Iran

Received 11 April 2014; Revised 19 July 2014; Accepted 21 July 2014; Published 31 August 2014

Academic Editor: Kai-Kit Wong

Copyright © 2014 Mehdi Ghamari Adian and Mahin Ghamari Adyan. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The core aim of this work is the maximization of the achievable data rate of the secondary user pairs (SU pairs), while ensuring the QoS of primary users (PUs). All users are assumed to be equipped with multiple antennas. It is assumed that when PUs are present, the direct communication between SU pairs introduces intolerable interference to PUs and thereby SUs transmit signal using the cooperation of one of the SUs and avoid transmission in the direct channel. In brief, an adaptive cooperative strategy for MIMO cognitive radio networks is proposed. At the presence of PUs, the issue of joint relay selection and power allocation in underlay MIMO cooperative cognitive radio networks (U-MIMO-CCRN) is addressed. The optimal approach for determining the power allocation and the cooperating SU is proposed. Besides, the outage probability of the proposed system is further derived. Due to high complexity of the optimal approach, a low complexity approach is further proposed and its performance is evaluated using simulations. The simulation results reveal that the performance loss due to the low complexity approach is only about 14%, while the complexity is greatly reduced.