1. Department of Mathematics, University of Oum el Bouaghi, Oum El Bouaghi 04000, Algeria
2. Department of Mechanical Engineering, University of Manitoba, Winnipeg, MB R3T 5V6, Canada
3. Communication Systems and Networks Research Group, Department of Information Systems, Faculty of Computing and Information Technology, King Abdulaziz University, Jeddah 21589, Saudi Arabia
4. Mathematical Institute, University of Oxford, Oxford OX2 6GG, UK