1. Sun-Air Research Institute, Ferdowsi University of Mashhad, Mashhad, Iran
2. Faculty of Engineering, Department of Electrical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
3. School of Engineering, University of East Anglia, Norwich, U.K.
4. Department of Electrical and Computer Engineering and the Instituto de Telecomunicações, University of Coimbra, Coimbra, Portugal