On Detecting Spectrum Opportunities for Cognitive Vehicular Networks in the TV White Space

We overview the challenges related to spectrum awareness in the vehicular environment, with emphasis on awareness in the TV licensed band. In the vehicular environment the cognitive radio can help to: 1) satisfy capacity demand for Intelligent Transportation Systems (ITS) applications; and 2) offload time insensitive applications from the ITS dedicated spectrum. However, using simple propagation models we show that neither sensing, nor geolocation database lookup alone can provide sufficient incumbent protection. Collaboration among the sensors to take advantage of spatial diversity is difficult due to the rapidly changing network topology. Nevertheless, mobility provides the opportunity to use time diversity at each sensor. We also discuss the influence of sensing subsystem design on the vehicular cognitive network medium access (MAC) sublayer. Whenever appropriate, we evaluate applicability of the requirements imposed by the Federal Communications Commission (FCC) and the IEEE 802.22 standard to the cognitive vehicular networks.