Dynamic Spectrum Access: Architectures and implications

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.