Discrete Fourier transform (DFT) modulated filter banks (FBs) are considered as strong tools used to implement both dynamic spectrum access and spectrum sensing in cognitive radio (CR) systems. High time-frequency (TF) resolution for spectral estimation and effective spectrum access with low complexity transceivers are the basic objectives in CR systems. However, the limitations of self-interference in DFT FBs as well as a primary user interference increase the overall transceiver complexity. In this paper, we design DFT modulated FBs which take into account the aforementioned contradicting requirements of high resolution capabilities, efficient spectrum access and affordable implementation effort for an additive white Gaussian channel. Four simple designs are presented and their performance are investigated and compared for a CR system with basic transmission parameters resembling those of IEEE 802.11g.

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A discrete Fourier transform (DFT) modulated filter bank (FB) transceiver architecture is considered which can be used for both spectrum sensing and spectrum access in cognitive radio systems operating in delay dispersive fading channels. A simple post-detection integration at the secondary user receiver using the FB output signals is employed for signal demodulation of differential phase-shift keying symbols transmitted on a set of subcarriers. A constrained optimization design for the FB prototype filter coefficients is proposed which combines timefrequency (TF) concentration properties for spectrum sensing with system specifications in terms of the maximum allowed bit-error rate (BER) for the fading channel characteristics and models the primary user signal as a Gaussian distributed process. The FB TF resolution properties as well as the BER performance are investigated for transmission with a raw bit rate of 30 Mbit/s in an indoor scenario.