Out-of-Band Sensing for Seamless Communication in Cognitive Radio Systems

Cognitive radio is a key to resolve scarcity of radio spectrum. To exploit unused spectrum bands, cognitive capable devices called secondary users should perform spectrum sensing; but need to vacate the band, when a licensee of the band, i.e. a primary user, appears. For seamless communication in this case, they should discover a free channel to switch to; this can be done by out-of-band sensing before leaving the current channel. When there is a single radio transceiver, out-of-band sensing use part of the MAC frame that would be used for data transmission otherwise. To maintain a reasonable throughput, we need to find an appropriate period for out-of-band sensing. In this paper, we develop an algorithm that drives the period to a steady state. Numerical results show that our algorithm provides seamless communication with insignificant effect on the throughput.