Scalability of UWB Cognitive Radio Networks with Interference Constraint

To achieve scalable wireless design utilizing Ultra- Wide-Band (UWB), cognitive radio, and hybrid network (ad-hoc with infrastructure such as AP, access point), we propose a cooperative interference adaptation method, where a node by sensing the frequency spectrum, can adapt its transmit power to maximize its throughput capacity under the aggregate interference constraint. By developing an AP-assisted percolation model from a hierarchy of hexagons, we analyzed the asymptotic per-node throughput and per- packet delay of this method, as the density of randomly distributed nodes in a unit disk grows. We find that a throughput-optimum density exists for a given fading coefficient and maximum transmit power, a result applicable to wireless Internet and sensor networks.