[Liu, Jingxian;Xiong, Ke] Beijing Jiaotong Univ, Sch Comp & Informat Technol, Beijing, Peoples R China.^[Zhao, Zhuyan] Nokia Siemens Networks, Beijing, Peoples R China.^[Zhong, Shaohong] Cent South Univ Forest & Technol, Sch Comp & Informat Engn, Changsha, Hunan, Peoples R China.^[Zhong, Zhangdui;Ai, Bo] Beijing Jiaotong Univ, State Key Lab Rail Traff Control & Safety, Beijing, Peoples R China.^[Zhong, Zhangdui;Ai, Bo] Beijing Jiaotong Univ, Beijing Engn Res Ctr High Speed Railway Broadband, Beijing, Peoples R China.