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Journal of Optimization
Volume 2014, Article ID 325217, 10 pages
http://dx.doi.org/10.1155/2014/325217
Research Article

Beamforming with Reduced Complexity in MIMO Cooperative Cognitive Radio Networks

Electrical Engineering Department, University of Zanjan, Zanjan 45371-38791, Iran

Received 26 June 2013; Revised 30 January 2014; Accepted 26 February 2014; Published 6 May 2014

Academic Editor: Kai-Kit Wong

Copyright © 2014 Mehdi Ghamari Adian. 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

An approach for beamforming with reduced complexity in MIMO cooperative cognitive radio networks (MIMO-CCRN) is presented. Specifically, a suboptimal approach with reduced complexity is proposed to jointly determine the transmit beamforming (TB) and cooperative beamforming (CB) weight vectors along with antenna subset selection in MIMO-CCRN. Two multiantenna secondary users (SU) constitute the desired link, one acting as transmitter (SU TX) and the other as receiver (SU RX) and they coexist with single-antenna primary and secondary users. Some of single antenna secondary users are recruited by desired link as cooperative relay. The maximization of the achievable rates in the desired link is the objective of this work, provided to interference constraints on the primary users are not violated. The objective is achieved by exploiting transmit beamforming at SU TX, cooperation of some secondary users, and cooperative beamforming. Meanwhile, the costs associated with RF chains at the radio front end at SU RX are reduced. Through simulations, it is shown that better performance in the desired link is attained, as a result of cooperation of SUs.