As highlighted in the Work Programme, energy efficiency and flexibility in the use of spectrum resources are two major research challenges for the development of future wireless communications technologies.To address these challenges, SACRA project proposes to develop a multi-band cognitive radio technology. In SACRA, new techniques for the global efficiency of wireless systems will be developed in the following four directions:- the spectral efficiency thanks to the use of cognitive radio techniques in a multi-band scheme,- the minimization of electronic component number in wireless systems,- the energy optimization for wireless communication terminals by optimizing architecture design and algorithms implementation,- the minimization of the generated interference in the environment by selecting the adequate band which will guarantee the shortest transmission distance and the minimum power while preserving the QoS.The innovation and impact brought by SACRA project are in the combination of innovative approaches on Radio Frequency (RF) front-end and base band components design with new cognitive radio techniques integrated into a demonstrator platform. The major outcome of SACRA project is a proof-of-concept able to communicate jointly and cognitively in two separate frequency bands, which corresponds to concrete needs today in Europe. The initial target scenario is the management and optimal distribution of broadband mobile communications on two separate frequency bands at 790-862 MHz and 2.6 GHz as proposed by European regulation authorities.Considering the current ICT challenges, SACRA project, by designing and validating new techniques for spectrum and energy efficiency in wireless communications, is expected to have a significant impact on future wireless mobile systems.