Restless Watchdog: Monitoring Multiple Bands with Blind Period in Cognitive Radio Systems

Spectrum sensing, which monitors the spectrum activity, is studied for cognitive radio systems using multiple frequency bands with non-negligible band switching time (blind period). Due to hardware limitation, it is assumed that only a subset of frequency bands can be monitored simultaneously. The problem of controlling the monitoring procedure is studied in the frameworks of dynamic programming (DP). System states and cost functions are defined. Cost-to-go functions for DP are derived, simplified and approximated, based on which control policies are derived. Numerical results are provided to demonstrate the proposed algorithms.