1. a Graduate Institute of Communications Engineering and Department of Electronic Engineering, National Changhua University of Education, 1 Jin-De Road, Changhua, Taiwan 500, R.O.C.
2. b Graduate Institute of Communications Engineering and Department of Electronic Engineering, National Changhua University of Education, 1 Jin-De Road, Changhua, Taiwan 500, R.O.C.
3. c Graduate Institute of Communications Engineering and Department of Electronic Engineering, National Changhua University of Education, 1 Jin-De Road, Changhua, Taiwan 500, R.O.C.