1. College of Electronic Engineering, National University of Defense Technology, Hefei 230037, China
2. College of Communications Engineering, Army Engineering University of PLA, Nanjing 210007, China
3. Academy of Military Sciences of PLA, Beijing 100091, China
4. College of Communications Engineering, Army Engineering University of PLA, Nanjing 210007, China; College of Information Science and Engineering, Jinshen College of Nanjing Audit University, Nanjing 210023, China