1. Key Laboratory of Electronic Information of State Ethnic Affairs Commission, College of Electrical Engineering, Southwest Minzu University, Chengdu, China
2. College of Electrical Engineering, Southwest Minzu University, Chengdu, China
3. School of Electronic Information and Electrical Engineering, Chengdu University, Chengdu, China
4. Engineering Research Center for Tibetan Information Processing, School of Information Science and Technology, Tibet University, Lhasa, China