1. Department of Communication EngineeringNational Central University 300 Jungda Road, Jungli City Taoyuan, 320 Taiwan
2. Green Technology Research CenterChang Gung University Taoyuan, 333 Taiwan
3. Department of Electrical and Electronic Engineering, Chung Cheng Institute of TechnologyNational Defense University Taoyuan, 33551 Taiwan
4. Department of Electronic EngineeringChang Gung University Taoyuan, 333 Taiwan