ESCAPE: A Channel Evacuation Protocol for Spectrum-Agile Networks

Preliminary studies and general observations reveal a significant amount of "white space" in radio spectrum that varies in frequency, time, and geographic locations. Driven by regulatory initiatives and radio technologies advances, opportunistic usage of the white space can potentially relieve the current spectral crunch. In this paper, we consider a scenario in which secondary users can opportunistically access unused spectrum vacated by idle primaries. In such a spectrum-agile system, a critical and unique issue is the fast and reliable evacuation of secondary users upon the return of primary users. To address this need, we propose an in-band signaling scheme, named ESCAPE. We present the basic design of the ESCAPE protocol in physical, MAC, and routing layers. The proposed scheme is distributed, reliable, and places minimum extra requirements on the spectrum-agile user transceivers.