Detailed survey and discussion on several potential key technologies are provided for the future wireless communication systems, such as heterogeneous wireless networks, massive multiple-input multiple-output (MIMO) communications, green communications and millimeter wave communications. First, the appearance of complicated interference signals and the increase of energy consumption resulted from the change of the heterogeneous structure in the future wireless communication networks are introduced. Second, the advantages, the state-of-the-art technologies and the difficulties of the massive MIMO are respectively analyzed. Then, the mathematical problems of maximizing spectrum efficiency, energy efficiency and resource efficiency are thoroughly described. Finally, the hybrid beamforming scheme of the millimeter-wave wireless communication system is given to deal with the lack of spectrum resource.