Abstract :
Dear Readers, With the publication of this issue, I do hope that you have an opportunity to take some of your time off to enjoy a wonderful summer. This issue includes a Special Issue on Cognitive Radio Networks: A Practical Perspective, which includes nine excellent articles collected by our Guest Editors, Carla-Fabiana Chiasserini, Maria-Gabriella Di Benedetto, Ping Zhang, and Xiangpeng Jing.
