[1] Univ Sci & Technol Beijing, Sch Math & Phys, Beijing 100083, Peoples R China
[2] Beihang Univ, LMIB, Beijing 100191, Peoples R China
[3] Beihang Univ, Sch Math & Syst Sci, Beijing 100191, Peoples R China
[4] Natl Univ Singapore, Dept Elect & Comp Engn, Singapore 119077, Singapore