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L. Bernadó, T. Zemen, A. Paier, J. Karedal:
"Performance Degradation of a Mismatched Wiener Filter for non-WSSUS Processes";
Talk: 8th COST2100 Management Committee Meeting, Valencia, Spain; 05-18-2009 - 05-19-2009; in: "Proceeding 8th COST2100 Management Committee Meeting", (2009), Paper ID TD(09)858, 8 pages.

A key component in vehicular communications
systems is the channel estimation filter that suppresses
the additive noise in the channel estimates from pilot
symbols. A filter which offers the best performance in terms
of mean square error (MSE) is the well known Wiener filter.
A drawback of using filters based on second order statistics
is that they have to be recalculated when the statistical
properties of the channel have changed. In vehicular
communications the observed channels do not follow the
wide-sense stationary (WSS) uncorrelated-scattering (US)
properties, and therefore their power spectral densities
vary over time. A non-stationary process can be split into
consecutive time regions where the WSS and US properties
are assumed to hold, which allows us to calculate the
coefficients of a Wiener filter. In this paper we present the
degradation of the MSE observed when using a mismatched
Wiener filter. The mismatch is created by using the filter
coefficients calculated for a past WSSUS region. We relate
this concept of performance degradation to the distance
between the filter coefficients by means of the spectral
divergence. We show that accepting a loss in performance
we can use the same filter coefficients over several time
regions, which allows computational complexity reduction
in a real system.

Vehicular communications, channel estimation, non-WSSUS