Ultra WideBand (UWB) is highly competent in satisfying many basic requirements of cognitive radio. Therefore, employing UWB in cognitive radio networks could be very instrumental for the successful penetration of cognitive radio into the wireless world. However, besides being a strong candidate for practical cognitive radio implementation, UWB can be considered as a supplement to cognitive radio systems that are realized by means of other wireless technologies. Therefore, it can be concluded that this way or the other, UWB will be an inseparable part of cognitive radio applications. UWB can offer various kinds of support to cognitive radio network. These include sharing the spectrum sensing information via UWB, locating the cognitive nodes in a cognitive network by means of IR-UWB, and sensing the physical environment/ channel with IR-Radar. In this paper,various cognitive UWB networks related issues including these supplementary uses of UWB will be discussed.