Frequency domain versus time domain based training sequence optimization

Two previously proposed training sequence optimization techniques for channel estimation are compared. One method is based on a frequency domain based channel estimation method (FD) and the other is based on a time domain channel estimation technique (TD). The FD method produces a lower complexity search strategy but does not always result in the optimal training sequences in terms of the mean-squared channel estimation error. A proof of the superiority of the TD method over the FD method is presented in this paper. Based on the proof an alternative search criterion is proposed, which generally performs better than the FD method while still enjoying the low search complexity