Identifying the presence and footprints of multiple incumbent transmitters

Cognitive networks share spectrum with incumbent, or pre-existing, networks by identifying their presence and not causing interference to them. Current methods to identify the presence of multiple incumbent transmitters require more information than is available to a cognitive network. In this paper, the energy received by cooperating CRs is used to identify the presence of multiple incumbent transmitters without knowledge of their locations, channel model, and communication protocols. Incumbents are distinguished as components of a Gaussian mixture model of the energy received by CRs. Furthermore, the algorithm finds each incumbent´s footprint, i.e., the CRs that can cause the incumbent interference.