1. Key Laboratory of Universal Wireless CommunicationsMinistry of EducationBeijing University of Posts and TelecommunicationsBeijing100 876People's Republic of China
2. Department of Communication EngineeringSchool of Infarmation EngineeringShenyang UniversityShenyang110 044People's Republic of China
3. Central Research Institute of Hua WeiShanghai200 233People's Republic of China