Funding for this research was provided by:
National Natural Science Foundation of China (61701197, 61571108, 61701284, 61761030)
Open Foundation of State Key Laboratory of Networking and Switching Technology (SKLNST-2016-2-14)
Open Foundation of Key Laboratory of Wireless Communication (2017WICOM01)
Fundamental Research Funds for the Central Universities (JUSRP11742, JUSRP11738)
the Open Research Fund of National Mobile Communications Research Laboratory (2018D15)
China Postdoctoral Science Foundation (2017M622233, 2017M622103)
Received: 18 November 2017
Accepted: 2 January 2018
First Online: 22 January 2018
: The authors declare that they have no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.