Daniela TUNINETTI - University of Illinois at Chicago Communication systems
Date: - Location: Eurecom
Smart and highly adaptive wireless devices hold the promise of increasing the spectral efficiency and reducing interference in wireless systems, which have long been recognized as crucial hindrances to better performance and sufficient spectrum for existing and new wireless services. In this talk we survey advances in cognitive radios by focusing on the capacity-achieving strategies and fundamental performance limits for the canonical example of the cognitive interference channel. The cognitive interference channel demonstrates in a simple and clear manner the rate advantages that may be obtained when one user?s message is also available at other nodes in the network. This knowledge can be obtained, in the wireless environment, by taking advantage of the broadcast nature of the medium and having ?intelligent? or ?cognitive? nodes overhear the transmissions taking place over the air. Although conceptually simple, this model has provided important insights on the optimal transmission strategies to be adopted for different interference levels at the decoders. Some of these strategies are intuitive: interference at the non-cognitive node can be treated as noise if sufficiently weak or decoded if sufficiently strong. For some intermediate regimes, we show that the optimal transmission strategy consists of having the cognitive node simultaneously control the interference at both the intended and the non-intended receivers. Recent extension to networks with more than two users will be discussed.
