State Key Laboratory of Rail Traffic Control and Safety, Beijing Jiaotong University, Beijing 100044, China;
School of Computer and Information Technology, Beijing Jiaotong University, Beijing 100044, China;
Department of Electronic Engineering, Tsinghua University, Beijing 100084, China;
Department of Electronic Engineering, Tsinghua University, Beijing 100084, China;
NEC Laboratories China, Beijing 100084, China;
NEC Laboratories China, Beijing 100084, China;
