Improving the accuracy of noise estimation when using decision feedback

In discrete multitone transmissions, decision feedback is an attractive and simple method to gain information about transmission channel conditions without having to use pilot subcarriers or training sequences. Decision feedback, however, is prone to errors caused by wrong decisions. A misestimation of the true channel conditions often occurs when the signal-to-noise ratio is suddenly decreased by a disturbance. In this paper, we present novel measures to increase the overall accuracy of channel estimation. In particular, we identify a special statistic whose evaluation yields reliable noise estimates even for very low signal-to-noise ratios.