Funding for this research was provided by:
National Natural Science Foundation of China (61801234)
Natural Science Foundation of Jiangsu Province (BK20160911)
Key International Cooperation Research Project (61720106003)
Postgraduate Research & Practice Innovation Program of Jiangsu Province (SJCX18_0276)
the open research fund of Key Lab of Broadband Wireless Communication and Sensor Network Technology (Nanjing University of Posts and Telecommunications), Ministry of Education (JZNY201701)
Received: 16 November 2018
Accepted: 7 May 2019
First Online: 3 June 2019
: The authors declare that they have no competing interests.
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