Research activities of the fifth generation mobile communication promotion forum radio access technologies towards the fifth generation mobile communications system

In this paper, latest research activities of radio access network technologies in the Fifth Generation Mobile Communication Promotion Forum and essence of its preceding works in ´ARIB 2020 and beyond ad hoc9 are reported. In order to serve variety of use cases in a flexible and efficient manner, "heterogeneous network" combining genuine new radio access technologies for `5G´ with other radio access technologies will be the key. The paper also summarizes studies on utilization of higher frequency spectrum in SHF or EHF bands, as well as several cutting edge radio access technologies being studied for `5G´.