Funding for this research was provided by:
National Natural Science Foundation of China (61471135, 61671165)
Natural Science Foundation of Guangxi Province (2013GXNSFGA019004, 2015GXNSFBB139007)
Fund of Guangxi Key Laboratory of Wireless Wideband Communication and Signal Processing (CRKL150104, CRKL160105)
Innovation Project of Guangxi Graduate Education (YCSZ2015144)
Innovation Project of GUET Graduate Education (2016YJCX91)