This chapter introduces spectrum authorization schemes and usage scenarios relevant for 5th generation (5G), as well as the spectrum usage requirements for these schemes and scenarios. It analyzes spectrum usage aspects at high frequencies, including propagation, coverage, deployment and co-existence. Spectrum bandwidth demand for 5G is discussed, by evaluating analysis tools, and elaborating on the impacts of 5G services and deployment scenarios on the spectrum demand estimation. The chapter deals with frequency bands for 5G, depicting bands identified or under study for IMT, but also further potential candidate bands, as well as spectrum roadmaps for the 5G launch. It discusses the propagation challenges at high frequencies in order to give an understanding of the operational environments. The chapter also discusses evolutionary paths for the practical implementation of dynamic spectrum management, and possible functional architecture covering both, the operator and the regulator domain.