This Chapter considers regulatory and technical aspects of the frequency assignment and licensing process for national radio systems. On one hand, frequency assignments must provide for the normal operation of existing radio systems as well as for new systems with a specified performance. On the other hand, in view of a great and ever growing public demand, frequency assignment procedures should strive to ensure the permissible level of interference among radiocommunication services, among stations within each service, as well as efficient utilization of the radio-frequency spectrum and the satellite orbits. For some applications (e.g. broadcasting and mobile services) appropriate frequencies for different sites may be determined in the aggregate in advance and these frequencies are assigned later during creation and expansion of relevant networks, as necessary. Such activity may be referred to as a “frequency-site” planning process. This may be an allotment process in some administrations.