[Liao Haibin;Chen Qinghu] Wuhan Univ, Sch Elect Informat, Wuhan 430079, Peoples R China.^[Wang Hongyong] Henan Univ Technol, Sch Informat Sci & Engn, Zhengzhou 450001, Peoples R China.^[Zhao Qianqian] Huazhong Normal Univ, Natl Engn Res Ctr E Learning, Wuhan 430079, Peoples R China.