Preamble-Assisted Channel Estimation in OFDM-based Wireless Systems

Abstract

Accurate channel state information (CSI) is indispensable for the use of channel-adaptive transmission techniques, but it may not easily be achievable near the cell boundary in cellular environments. This paper considers the improvement of CSI estimation accuracy in OFDM-based wireless packet transmission systems by exploiting the preamble signal as well as the pilot signal. The CSIs respectively estimated from the received preamble and pilot signal are combined according to the channel correlation between the preamble and the pilot signaling. The combining weight is analytically determined to minimize the mean squared error. When multiple antennas are employed for interference cancellation, the CSI of interference channels can also be estimated in a similar manner. The proposed scheme is applied to the mobile-WiMAX system to verify the effectiveness. Simulation results show that the proposed scheme is quite effective near the cell boundary.