Several Key Technologies for 6G: Challenges and Opportunities

5G networks have been widely deployed all over the world, which involve massive multiple-in-put multiple-output (MIMO), millimeter-wave communication, and other technologies to improve the performance of the whole system. In contrast, the emerging key technologies including terahertz (THz) communication, intelligent reflective surface (IRS), blockchain, and so on have been proposed to enhance the signal quality for the future 6G networks. IRS can program the signal propagation by intelligently controlling a large number of passive reflecting elements, and blockchain can improve the system security in the whole communication process. The article provides a survey of the recent research and compares the system performance between 5G and 6G, which can bring about the rapid increase in wireless data traffic and the achievable rate can be reached up to terabits per second to improve the communication quality dramatically.