1. Department of Fundamental Sciences, Faculty of Technical Sciences, University of Novi Sad, Novi Sad, Serbia.
2. Department of Mathematics and Informatics, Faculty of Sciences, University of Novi Sad, Novi Sad, Serbia.
3. Department of Power, Electronic, and Communication Engineering, Faculty of Technical Sciences, University of Novi Sad, Novi Sad, Serbia.
4. Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA 15213 USA.