Time domain equalization method for DFTS-OFDM signal without GI under high mobile environments

Abstract

In higher time-varying fading channels, the DFT Spreading-Orthogonal Frequency Division Multiplexing (DFTS-OFDM) signal would be damaged significantly by inter-channel interference (ICI) due to the loss of orthogonality among subcarriers which leads a fatal degradation of bit error rate (BER) performance. To solve this problem, this paper proposes a time domain equalization (TDE) technique in conjunction with a time domain channel impulse response (CIR) estimation method for the DFTS-OFDM signal. The salient features of proposed method are to employ a time domain training sequence (TS) in the estimation of CIR at every sampling time instead of using the conventional scattered pilots inserted in the frequency domain and to employ the TDE with a maximum likelihood (ML) estimation method in the demodulation of received time domain signal at every symbol instead of using the conventional frequency domain equalization (FDE) method. This paper presents various simulation results to demonstrate the effectiveness of proposed method for the DFTS-OFDM signal as comparing with the conventional FDE method.