A noise variance optimization method is proposed for the time and frequency dimension separate (2×1-D) Wiener-filtered channel estimation of OFDM based systems.According to Wiener-filter theory

the noise variance is necessary to achieve optimal solution.For 2×1-D Wiener-filtered channel estimation

the Wiener-filtering will be applied twice respectively in time and frequency dimension.Hence

the effect of variety of noise variance induced by the first filter should be considered on the second filter in this method

but it has not been considered in the existing 2×1-D Wiener-filtered channel estimation method.This paper presents a novel algorithm which takes into account the effect of variety of noise variance.In the proposed method

the noise variance used by the second filter is optimized according to the mean square error (MSE) of channel estimation by the first filter.The exact MSE of channel estimation is derived in this paper.Moreover

the channel estimation performance is evaluated with different noise variance optimizing criteria.The simulation results show that the performance of the proposed method is better than the 2×1-D filters method without noise variance optimization

and is very close to that of the Wiener 2-dimension filter.