info:eu-repo/grantAgreement/FCT/Concurso para Projectos de I&D em todos os DomÃnios CientÃficos - 2009/PTDC%2FEEA-TEL%2F115981%2F2009/PTOpportunistic Aggregation of Spectrum and Cognitive Radios: Consequences on Public Policies [PTDC/EEA-TEL/115981/2009]