Bandwidth scavenging for device coexistence in pervasive computing systems

Opportunistic Spectrum Access in a pervasive computing system can enable a set of secondary user devices to access unused spectrum, or whitespace, found between the transmissions of a set of primary user devices. The design objective for an efficient secondary user access strategy is to be able to “scavenge” spatio-temporally fragmented bandwidth while limiting the amount of disruption caused to the primary user devices. In this paper, we propose an access strategy which is based on measurement and modeling of the whitespace as perceived by the secondary user devices. A secondary user device continually monitors and models its surrounding whitespace, and then accesses the available spectrum so that the effective secondary throughput is maximized while the resulting disruption to the primary user devices is limited to a pre-defined bound. We first develop analytical expressions for the secondary throughput and primary disruption, and then perform ns2 based simulation experiments to validate its effectiveness under various topologies, user traffic profiles, and secondary user populations.