Cognitive Radio: A Communications Engineering View

Cognitive radio is an emerging technology that enables the flexible development, construction, production, shipping, and deployment of highly adaptive radios that are built upon software defined radio technology. This contribution starts with a brief section that underlines the paramount importance of the mobile radio communications channel. Then, spectrum issues are discussed to emphasize the reasons for spectrum scarcity as well as the importance of dynamic spectrum allocation. Some remarks about the development of software defined radio from digital radio lead to a discussion of the most important engineering aspects of CR, for example, location and spectrum awareness, transmission power control, and signal analysis. Because usually papers about CR are somewhat visionary, we first describe practical steps to an implementation of helpful CR properties into a mobile communication base station, as well as user terminal equipment. The article concludes with a short summary.