© DIGITAL VISION, ARTVILLE & STOCKBYTE IEEE SIGNAL PROCESSING MAGAZINE [90] MAY 2007 1053-5888/07/$25.00©2007IEEE W ireless communication has witnessed a continuous trend toward appli- cation diversification, leading to a significant growth in usage and serv- ices. With the proliferation of nomadic devices (SmartPhones, PDAs, laptops) and multimedia applications, user demand is progressively shifting from simple data-rate increase to complex and heterogeneous quality of service (QoS) requirements. With these devices being battery-powered, the per- formance requirements are coupled with severe constraints on energy efficiency. This is becoming a key concern: there exists a continuously growing gap between the available energy, resulting from battery technology evolution, and the steeply increasing energy requirements of emerging radio systems (Figure 1). Technology scaling, platform improve- ments, and circuit design progress are not sufficient for bridging this energy gap. A clear need for holistic system-level strategies exists. [ Antoine Dejonghe, Bruno Bougard, Sofie Pollin, Jan Craninckx, André Bourdoux, Liesbet Van der Perre, and Francky Catthoor ] Green Reconfigurable Radio Systems [ Creating and managing flexibility to overcome battery and spectrum scarcity ]