[1] Hunan Univ, Coll Comp Sci & Elect Engn, Changsha 410082, Hunan, Peoples R China
[2] Beijing Jiaotong Univ, Inst Informat Sci, Beijing 100044, Peoples R China
[3] Capital Normal Univ, Sch Math Sci, Beijing 100048, Peoples R China
[4] New Jersey Inst Technol, Dept Elect & Comp Engn, Newark, NJ 07102 USA