Institute of Electrical & Electronic Engineers
With opening up of the TV white spaces for opportunistic access, designing a flexible PHYsical layer (PHY) scheme has become an important focus for Cognitive Radio (CR) systems. Two possible PHY design solutions proposed are: Generalized Frequency Division Multiplexing (GFDM) and Interference Avoidance by Partitioned Frequency and Time domain transmission (IA-PFT). Both of these methods extend the Orthogonal Frequency Division Multiplexing (OFDM) scheme to be applicable as a flexible CR PHY solution in a fragmented spectrum. In GFDM, introduction of pulse shaping filters reduces the out-of-band radiation of the opportunistic signals into the frequency band of the incumbent users; while in IA-PFT, simultaneous cancellation carrier insertion and time windowing technique suppress spectral leakage into the incumbent band of operation.