Policy-based reasoning for spectrum sharing in radio networks

Regulation of spectrum may undergo revolutionary changes in the near future allowing a less restricted and more flexible access to radio spectrum. Intelligent radios, or so-called cognitive radios, will realize the dynamic usage of frequency bands on an opportunistic basis, by identifying and using under-utilized spectrum. Such a flexible spectrum usage requires changes in regulation towards a more open spectrum. Policies which determine when spectrum is considered as opportunity and which define the possibilities of using these spectrum opportunities are needed. This paper discusses two approaches of different complexity that intend to enable distributed QoS support in open spectrum. These algorithms are specified as policies in a machine-understandable policy description language, such that the cognitive radio is capable of reasoning about spectrum usage. Thereby not only a multitude of policies has to be combined but also measurements of local spectrum utilization and user/operator preferences have to be taken into account