1. School of Electronic and Information Engineering, Beijing Jiaotong University, Beijing, China
2. School of Electronic and Information Engineering, the State Key Laboratory of Advanced Rail Autonomous Operation, and the Beijing Engineering Research Center of EMC and GNSS Technology for Rail Transportation, Beijing Jiaotong University, Beijing, China
3. Signal and Communication Research Institute, China Academy of Railway Sciences, Beijing, China
4. Department of Engineering Technology and Didactics, Technical University of Denmark, Ballerup, Denmark