Suchergebnisse

The electromagnetic (EM) spectrum is the lifeblood of wireless communications and services. Accessing the spectrum has become ever-increasingly problematic. This is due to the current practices of frequency management based on pre-planned and static frequency allocation and assignments that can no longer accommodate explosive demands for EM spectrum. Without a paradigm shift in spectrum management, the growth of wireless services to meet demands, whether from commercial, civil, or military interests, will be severely curtailed in the coming years. In particular, spectrum-dependent devices, equipment, and systems will increasingly encounter significant competitive disadvantages, with critical consequences on our warfighting capability, when accessing the (seemingly or actually) overcrowded EM spectrum upon deployment in the U.S., and more so overseas. On the road forward, the transformation of spectrum management from the current static spectrum allocation and assignment to a more dynamic and responsive regime is greatly facilitated by the emerging concept of dynamic spectrum access (DSA) that enables spectrum-dependent devices, equipment, and systems to dynamically change their parameters to adapt their spectrum access according to criteria such as policy constraints, spectrum availability, propagation environment, and application performance requirements. In this paper, we present an overview of DSA architectures - opportunistic as well as coordinated, highlight their salient features, and focus on their implications on radios, networks, and spectrum usage which will provide responsive tactical and enabling strategic capabilities to the warfighter.

Planning and the Rural Environment.

From the University of Alberta comes a coolness towards conventional design in research. The architects and administrators, in expressing their personalities, may not do well by the researcher's personality. Readers will recall Dr. Som mer's fables concerning keys and power and secretaries and research produc tivity.

In this article, we argue that Niklas Luhmann has a lot to offer present-day planning theory. Until now, planning theory has been engaged with Luhmann's work only minimally. Convinced of its potential, we want to show how Luhmann's systems theory offers fresh insight into both limits and possibilities of planning in contemporary society. We argue that Luhmann's understanding of society as functionally differentiated into self-referentially closed subsystems (politics, economy, law, science, etc.) creates space for a complex and subtle analysis of planning practice. In particular, we look at the role of planning within an autopoietic account of society, and its ability to steer other social subsystems. Planning is seen as the form of steering aiming to coordinate processes of spatial organization, therefore an activity dealing with steering problems. We illustrate key concepts of the systems theory in brief analyses of planning situations and interpret these situations using the systems theoretical framework. The analyses center around the questions of planning's steering capacity and the role of the planner, thus creating linkages with mainstream discussions in planning theory.