Interference Cartography for Hierarchical Dynamic Spectrum Access

This paper describes a simple but effective concept in cognitive networks that provides awareness on the radio environment through geo-localized interference measurements: the interference cartography. The purpose of this novel concept is to combine location information with radio measurements carried out over the heterogeneous radio environment, and to provide a complete view of the environment to be used in autonomous decision making in a cognitive context. This is achieved by aggregating the already existing radio measurements that circulate in wireless networks forming the heterogeneous network panorama, combining this aggregated information with geo-localization information, performing advanced signal processing techniques to render the information complete and reliable, and updating the information to provide a viable picture of the environment for efficient detection, analysis and decision. Our focus is on hierarchical access models where licensed spectrum can be accessed by secondary users without creating harmful interference on the primaries. A complete description of a possible network implementation in a hierarchical access scheme is given, with a centralized architecture and a protocol structure that complies with the utilization of interference cartography. A case study of the proposed scheme is also given, demonstrating the utility of the notion of interference cartography.