1. School of Electronics and Information Engineering, Xi’an Siyuan University, Xi’an, Shanxi, P. R. China
2. School of Computer, Electronics and Information, Guangxi University, Nanning, Guangxi, P. R. China
3. Guangxi Key Laboratory of Multimedia Communications and Network Technology, Nanning, Guangxi, China
4. People’s Hospital of Guangxi Zhuang Nationality Autonomous Region, Nanning, Guangxi, China