1. College of Computer and Artificial Intelligence, Huaihua University, 418008 Huaihua, P. R. China
2. College of Information Science and Engineering, Hunan Normal University, 410081 Changsha, P. R. China
3. Communication Systems and Networks Research Group, Department of Electrical and Computer Engineering, Faculty of Engineering, King Abdulaziz University, 21589 Jeddah, Saudi Arabia