[1] Nanyang Technol Univ, Sch Elect & Elect Engn, Singapore 639798, Singapore
[2] UNSW Sydney, Sch Elect Engn & Telecommun, Sydney, NSW 2052, Australia
[3] City Univ Hong Kong, Dept Elect Engn, Hong Kong, Peoples R China
[4] Shandong Univ, Sch Elect Engn, Jinan 250061, Peoples R China
[5] Zhejiang Univ, Coll Elect Engn, Hangzhou 310027, Peoples R China