An Efficient FFT For OFDM Based Cognitive Radio On A Reconfigurable Architecture

Cognitive radio is a promising technology to utilize non-used parts of the spectrum that actually are assigned to licensed services. An adaptive OFDM based cognitive radio system has the capacity to nullify individual carriers to avoid interference to the licensed user. Therefore, there could be a considerably large number of zero-valued inputs/outputs for the IFFT/FFT in the OFDM transceiver. Due to the wasted operations on zero values, the standard FFT is no longer efficient. Based on this observation, we propose to use a computationally efficient IFFT/FFT as an option for OFDM based cognitive radio. Mapping this algorithm onto a reconfigurable architecture is discussed.