On the characteristics of spectrum-agile communication networks

Preliminary studies as well as general observations indicate the presence of a significant amount of "white space" in radio spectrum, varying on frequency, time, and geographic locations. Thus, it is likely that spectrum access, instead of true spectrum scarcity, is the limiting factor of potential growth of wireless services. Enabled by regulatory changes and radio technologies advances, opportunistic usage of the white space has the potential to significantly mitigate the spectrum scarcity. In this paper, we study the characteristics of opportunistic spectrum availability and its exploration. We present two new metrics to capture unique characteristics in networks with spectrum agility, namely equivalent non-opportunistic bandwidth and space-bandwidth product. Equivalent non-opportunistic bandwidth is a metric to quality the utilization of white space that is opportunistically available to secondary users. Space-bandwidth product qualifies the reuse in both spatial and frequency domain. Heterogeneity in channel availability and footprints are shown to be beneficial. We also study the spatial and temporal properties of opportunistic spectrum availability