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This paper proposes an improved discrete Fourier transform-based and pilot-symbol-aided channel estimation (DFT-based PSA CE) for coherent orthogonal frequency division multiplexing (OFDM) systems. Conventional DFT-based PSA CE suffers from the dispersive distortion of an estimated channel impulse response (CIR) caused by virtual carriers. The proposed method estimates an equal-spaced channel frequency response (CFR) in a virtual carrier region by using forward and backward linear prediction (FBLP). Simulation results show that the proposed method outperforms the conventional one with slightly increased complexity and provides a performance similar to the frequency domain linear minimum mean square error (LMMSE) channel estimation with significantly reduced complexity.

A time-varying multipath channel causes co-channel interference (CCI) as well as inter-carrier interference (ICI) in a space-time block coded orthogonal frequency-division multiplexing (STBC-OFDM) system using two transmit antennas and an conventional simplified decoding scheme (SDS). In this paper, we derive the power of the CCI as a function of normalized channel variation rate. Also, we propose a successive interference cancellation (SIC) technique to improve the performance of the STBC-OFDM by considering the CCI mechanism. The proposed SIC technique can compensate the CCI to some extend with slightly increased complexity compared to the SDS.