Performance study of OFDM receiver using FFT based on log number system

Abstract

In this paper, we study the performance of the OFDM receiver using FFT based on the log number system (Log-FFT) in a wireless environment. By using the log number system (LNS), complex multiplications of the FFT are reduced to simple additions. The effect of finite bit precision on the receiver performance is analyzed theoretically under the AWGN channel. Simulation results for both AWGN and fading channels are presented. It is shown that the bit width requirement of the receiver is quite small. In a coded OFDM system, there is no degradation in bit error rate performance when only two fractional bits are used for the LNS under a slow fading channel. The size of the look-up tables are small and the complexity of the log-FFT implementation is simple. Thus log-FFT is an attractive implementation method for the OFDM receiver design in wireless environment.