1. National Key Laboratory of Science and Technology on Communications; University of Electronic Science and Technology of China; Xiyuan Avenue 2006, High-Tech West Zone Chengdu Sichuan 611731 China
2. Chengdu Huawei Research Center; Huawei Technology Co. Ltd.; Xiyuan Aven‘899, High-Tech West Zone Chengdu Sichuan 611731 China
3. China Mobile Research Institute; 32 Xuanwumen West Street, Xicheng District Beijing 100053 China