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Low-Power FFT Design for NC-OFDM in Cognitive Radio Systems  

Jang, In-Gul (전북대학교 전자공학부, IT융합 연구센터)
Chung, Jin-Gyun (전북대학교 전자공학부, IT융합 연구센터)
Publication Information
Journal of the Institute of Electronics Engineers of Korea TC / v.48, no.6, 2011 , pp. 28-33 More about this Journal
Abstract
Recently, the investigation of the cognitive radio (CR) system is actively progressed as one of the methods for using the frequency resources more efficiently. In CR systems, when the frequency band allocated to the incumbent user is not used, the unused frequency band is assigned to the secondary user. Thus, the FFT input signals corresponding to the actually used frequency band by the incumbent user are assigned as '0'. In this paper, based on the fact that there are many '0' input signals in CR systems, a low-power FFT design method for NC-OFDM is proposed. An efficient zero flag generation technique for each stage is first presented. Then, to increase the utility of the zero flag signals, modified architectures for memory and arithmetic circuits are presented. To verify the performance of the proposed algorithm, 2048 point FFT with radix-24SDFstructureisdesignedusingVerilog HDL. The simulation results show that the power consumption of FFT is reduced considerably by the proposed algorithm.
Keywords
Cognitive Radio; FFT; NC-OFDM; Power consumption; Memory access;
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