1. Department of Electrical Engineering, Ocean University of China, Qingdao 266100, China
2. School of Physics and Electronic Engineering, Taishan University, No. 525 Dongyue Street, Tai’an City, China
3. Technical Engineering Department of CRRC Qingdao Sifang Co., Ltd., Qingdao 266111, China
4. Department of Information Science Technology, Qingdao University of Science and Technology, Qingdao 266061, China
5. Department of Electrical and Computer Engineering, University of Victoria, Victoria, BC, Canada V8W 2Y2