Frequency Sharing Between the Broadcasting-Satellite Service and Other Radiocommunication Services

Most radiocommunication services, including the space services, share their frequency allocations with other services. Frequency sharing involving the broadcasting-satellite service is particularly difficult because of several factors. The allocations differ between the three ITU Regions of the world; the characteristics of broadcasting-satellite systems make them not only quite vulnerable to certain kinds of interference, but also make them major sources of interference to other systems; and certain key parameters of broadcasting satellites (carrier frequencies, orbital positions, beam dimensions and pointing, polarization, and e.i.r.p.) are prescribed by "closely packed" international assignment plans. This paper describes the sharing situations that have been created by the ITU's Table of Frequency Allocations, the sharing criteria which have been adopted to facilitate sharing, the criteria which need to be developed for certain bands, the interregional and interservice limits that have been incorporated in the Plans for broadcasting satellites, and the technical problems requiring study by international organizations. Measures to facilitate sharing are listed, and the significance of the forthcoming ITU Space Services Planning Conference is discussed.