Kalman interpolation filter for channel estimation of LTE downlink in high-mobility environments

Xuewu Dai,John E Mitchell,Wuxiong Zhang,Yang Yang,Jing Xu

doi:10.1186/1687-1499-2012-232

Abstract

Abstract The estimation of fast-fading LTE downlink channels in high-speed applications of LTE advanced is investigated in this article. In order to adequately track the fast time-varying channel response, an adaptive channel estimation and interpolation algorithm is essential. In this article, the multi-path fast-fading channel is modelled as a tapped-delay, discrete, finite impulse response filter, and the time-correlation of the channel taps is modelled as an autoregressive (AR) process. Using this AR time-correlation, we develop an extended Kalman filter to jointly estimate the complex-valued channel frequency response and the AR parameters from the transmission of known pilot symbols. Furthermore, the channel estimates at the known pilot symbols are interpolated to the unknown data symbols by using the estimated time-correlation. This article integrates both channel estimation at pilot symbols and interpolation at data symbol into the proposed Kalman interpolation filter. The bit error rate performance of our new channel estimation scheme is demonstrated via simulation examples for LTE and fast-fading channels in high-speed applications.

Highlights

Channel estimation plays an important role in communication systems and, in the 3rd Generation Partnership Project (3GPP) Long-Term Evolution (LTE) which aims at continuing the competitiveness of the 3G Universal Mobile Telecommunications System technology
We present a combined estimation and interpolation scheme, where the time correlation among consecutive Orthogonal frequency-division Multiple Access (OFDM) symbols is taken into account to estimate the channel frequency response (CFR) at the known pilot symbols and to interpolate to estimate the CFR at the unknown data symbols at the pilot subcarriers
This article focuses on channel estimation and interpolation for a time-varying multipath fading channel in 3GPP LTE downlink

Summary

Introduction

Channel estimation plays an important role in communication systems and, in the 3GPP Long-Term Evolution (LTE) which aims at continuing the competitiveness of the 3G Universal Mobile Telecommunications System technology. Reception model yk 1⁄4 Xkhk þ wk in (9), the task for the Kalman interpolator filter can be stated as: Given the matrix Xk of known transmitted pilot symbols and received signal yk at kth OFDM symbol, to obtain minimum variance estimates of the time-varying multipath CFR hk and interpolate hk to the followed six fk þ 1; k þ 2; .

Results

Conclusion