1. Faculty of Engineering and Computer Science, German University of Technology in Oman, P.O. Box 1816, Muscat 130, Oman
2. Communication Technology, Duisburg Essen University, Oststraße 99, 47057 Duisburg, Germany
3. School of Business Administration, Al Akhawayn University in Ifrane, BP104, Ifrane 53000, Morocco
4. Department of Mathematical and Physical Sciences, University of Nizwa, P.O. Box 33, Nizwa 616, Oman