Abstract

Abstract:Cognitive radios are beingstudied intensively these days. The major motivation for this is the heavilyunderutilized frequency spectrum. Cognitive radio is basically the technique toreuse the unused spectrum to increase the total system capacity by allowing agroup of secondary users to share the radio spectrum originally allocated tothe primary users. This sharing of the spectrum is termed as dynamic spectrumaccess. In the process of spectrum sharing cognitive radio locates the idle frequency bands to transmit thedata.  During the transmission of datacognitive radio repeatedly checks the reappearance of the primary users andimmediately stops the transmission and moves to the other idle frequency bandonce the primary user is detected. The collision of cognitive radio’stransmitted data with the primary user’s data due to some missed detection istermed as the “Interference” and leads to degradation of quality of service of theprimary user as well as cognitive radio user. This paper reviews the enablingtechnology of cognitive radio and the techniques employed for the mitigation ofthe interference.