LEI Ke-jun1, 2, TAN Yang-hong1, YANG Xi3, WEN Juan1
( 1.College of Electrical and Information Engineering, Hunan Univ, Changsha, Hunan 410082, China; 2.College of Information Science and Engineering, Jishou Univ, Jishou, Hunan 416000, China; 3.School of Information Science and Engineering, Southeast Univ, Nanjing, Jiangsu 210096, China)