Theoretical Analysis of Decision Directed Block Iterative Channel Estimation for OFDM Mobile Radio

Orthogonal frequency division multiplexing (OFDM) is one of the promising transmission techniques for next generation mobile communication systems. Accurate channel estimation is essential for coherent OFDM signal transmissions. So far, many pilot-assisted channel estimation schemes have been proposed. In the case of packet transmission, channel estimation on the same received packet can be repeated many times using the decision feedback to improve the channel estimation accuracy, resulting in decision directed block iterative channel estimation (DD-BICE). However, decision feedback of erroneously detected data symbols degrades the resulting bit error rate (BER) performance. A 2-dimensional (2D) averaging filter can be used for reducing the impact of decision feedback errors. In this paper, a theoretical analysis is presented for DD-BICE taking into account the decision feedback errors assuming quadrature phase shift keying (QPSK) data modulation. The impact of 2D averaging filter is discussed and the validity of the theoretical analysis is confirmed by computer simulation.