Dynamic Spectrum: Going Full Circle

Recent technological progress has brought new life to the notion of "just-in-time" spectrum management, raising the concern that further development is being held back by archaic regulatory restrictions imposed by spectrum managers. In the search for a solution, it has become clear that several interdisciplinary challenges still undermine the concepts of Dynamic Spectrum Access (DSA) and Dynamic Spectrum Management (DSM). In this paper we take a step back from the technical detail of implementation and focus on identifying the key milestones to the success of DSM. In identifying a roadmap for DSM, we look at the history of spectrum regulation, charting the key events in the transformation from free and open spectrum into the tightly regulated system of "Command & Control" that exists today. We outline the similarities between DSM and open spectrum and build on these to present the timeline for spectrum management in terms of a spectrum spiral. We expand on this roadmap, breaking down the key drivers and barriers at each milestone. We conclude that without spectrum scarcity, the concept of DSM is meaningless. But, given that prime spectrum is thought to be scarce, the key remaining barrier to the success of DSM is that of commercial viability.