The need for the radio spectrum for the rapidly growing broadband access services is evident. Abundant and fast access to spectrum has three main advantages: it fosters rapid innovation in wireless systems and services lowering entry barrier on the market; it enables affordable mobile broadband access to all; and makes new energy efficient wireless systems possible. Secondary use of already licensed, but poorly inefficiently used spectrum, (Cognitive Radio )has been proposed as a solution to make more efficient use of the spectrum. Low spectrum occupancy in a number of measurement campaigns worldwide has been the basis for claims of large gains in spectrum efficiency by cognitive radio. However, little research has been done to substantiate these claims. The QUASAR project aims at bridging this gap between the claims made in conventional cognitive radio research and practical implementation by assessing and quantifying the "real-world" benefits of secondary (opportunistic) access to primary (licensed) spectrum. The analysis is based on two key features of cognitive radio: the ability of the secondary users to discover the opportunity to use the spectrum, and assessing the electromagnetic impact of secondary user transmissions on primary system (receivers). Novel approaches are taken as we go beyond the conventional notion of detecting "spectrum holes" into treating spectrum opportunity discovery as a data fusion problem, as well as new schemes that cope interference from multiple uncoordinated secondary users. QUASAR will provide a comprehensive analysis of the techno-economical environment and provide detailed roadmaps and guidelines on how to apply and analyze new opportunistic spectrum access business models. The project will finally provide specific and reasoned proposals to go beyond the current regulatory framework. A balanced project team will provide results of high scientific quality and strong impact on the regulatory process and wireless business.