RF Front-End Architecture for Cognitive Radios

The cognitive radio (CR) concept relies on observing the surrounding radio spectrum, sensing changes and reacting accordingly, therefore a CR-enabled user equipment (UE) demands enhanced strategies for efficient interference detection, rapid spectrum evaluation and a highly flexible, reconfigurable architecture to be able to support the multitude of today´s as well as future radio access technologies (RATs). It is shown that classical methods of spectrum analysis like the fast Fourier transformation (FFT) have critical shortcomings in fullfilling the requirements of CR and how analog keyblocks like the wideband SigmaDelta-ADC can be implemented. The pivotal focus of this paper is to propose alternative approaches suitable for integration into the digital front-end (DFE) and the UE.