A frequency domain subspace blind channel estimation method for trailing zero OFDM systems

The technique of orthogonal frequency division multiplexing (OFDM) is widely used for high-speed data transmission in indoor and outdoor communication networks. Trailing zero (TZ) OFDM systems possess some favorable features compared to conventional cyclic prefixed OFDM systems. In this paper, we propose a blind channel estimation method for TZ-OFDM systems in the frequency domain. The significance of the proposed method is threefold. First, it gives an insight into the characteristics of TZ-OFDM systems from a frequency domain perspective. The characteristics revealed are not clearly manifest in the time domain. Second, by exploiting the desirable property brought by the trailing zeros and making use of the frequency domain samples available at the TZ-OFDM receiver, the frequency domain subspace based blind channel estimator is straightforward in concept and algorithm derivation as opposed to a time domain formulation. Third, the proposed method explicitly addresses the issue of unknown channel length. The new method is theoretically proven and numerically shown to work effectively for channels of unknown length. Simulation results demonstrate the satisfactory performance of the proposed method as compared to the existing methods and its robustness to channel overestimation.