Modified Decision Feedback Method for Mobile OFDM Channel Estimation

Abstract

In some frame-based OFDM applications such as WLAN and WMAN, the channel estimation is accomplished through the aid of the preamble. By means of the preamble, the estimated channel is only well applied under the assumption of a static channel status within the frame. If we consider a time-varying channel status in those applications, the channel tracking has to be performed without the aid of pilots. A past idea for channel tracking was to use a decision-feedback loop with a smoothing method to reduce the drawback of decision-error propagation. In our work, we design the error detectors for detecting error propagation and propose some compensation methods for reducing the influence of error propagation. In simulation results, the performance of the proposed decision-error detectors and compensation methods is compared. We show that the smaller bit error rate can be achieved for the proposed time domain decision feedback algorithm and thus, bandwidth efficiency can remain without the pilots used for channel tracking.