[1] Nanyang Technol Univ, Sch Elect & Elect Engn, Singapore 639798, Singapore
[2] JPT Elect Pte Ltd, 8 Boon Lay Way,11-09,Tradehub 21, Singapore 609964, Singapore
[3] Shaanxi Normal Univ, Sch Phys & Informat Technol, Xian 710062, Shaanxi, Peoples R China