With the unceasing expansion of mobile communication network and the explosive growth of mobile Internet, more and more attention has been paid to the shortage of spectrum resources, the huge energy consumption and to network optimization. Innovative solutions are required to enhance the spectrum efficiency With the unceasing expansion of mobile communication network and the explosive growth of mobile Internet, more and more attention has been paid to the shortage of spectrum resources, the huge energy consumption and to network optimization. Innovative solutions are required to enhance the spectrum efficiency