Research of Transparent RIS Technology toward 5G evolution & 6G

The introduction of 5G commercial services has begun throughout the world, and at present, research toward the further development of 5G (5G evolution) and the development of 6G as the next-generation mobile communications sys-tem is being actively pursued. In this article, we describe IRE, an important concept in “New Radio Network Topology” now under discussion on the road to 5G evolution & 6G. We also describe NTT DOCOMOʼs initiatives toward RIS, an important component of IRE, and metamaterial/metasurface technologies as elemental technologies of RIS.