Opportunistic spectral access through suppression of impulsive interference

Abstract

Cognitive radios are slated to be the next generation of smart transceivers that can opportunistically access spectrum through dynamic sensing of their immediate radio frequency (RF) environment. Such spectral sharing will be limited primarily by the interference that a cognitive user may potentially cause to the licensed primary user of the band. In particular, all cognitive transmitters located within a certain region of interference of a primary user will have to refrain from transmitting data. Given that most cognitive users will need to transmit data only intermittently and that there will be only a finite number of such users in the RF neighbourhood of a primary user, it is conceivable that the resulting interference at the primary will be more structured than can be described by a white Gaussian noise model. This opens the door for interference mitigation techniques that exploit the interference structure. In this work, methods to mitigate the effects of potentially harmful interference caused by active secondary users through intelligent signal processing at the receiver of the primary user are investigated, such that the perimeter of the region of interference can be reduced, creating greater opportunities for the secondary users while meeting interference constraints. Receiver structures for the more practical scenario of temporally correlated interference are introduced, and the achievable gains when applying simple yet effective interference suppression methods are quantified.