The selective transmission with majority even/odd subcarriers for the high data throughput in OFDMA based Cognitive Radio systems

The novel method for increasing the data transmission throughput in OFDMA based Cognitive Radio system was proposed. The vacant spectrum which the primary OFDMA user is not using consists of even or odd subcarriers in IFFT. If the secondary user transmits data set using only even or odd subcarriers of vacant IFFT subcarriers, such a generated OFDMA symbol has symmetrical waveform. It is possible to recover the transmitted data set at receiver with only half part of OFDMA symbol transmitted during first half of OFDMA symbol duration. Therefore another different data set can be transmitted during second half of OFDMA symbol duration, which can increase the data transmission throughput. In this paper, the signal processing block with only even or odd subcarriers in IFFT was described and its receiver structure with pruning FFT was shown. And the throughput efficiency analysis was shown with the effect of overhead data for cyclic prefix as well as SNR gain which can be given to the proposed method with lower PAPR than the normal OFDMA signal.