An improved block equalization scheme for uncertain channel estimation

• Published in: IEEE transactions on wireless communications Vol. 6; no. 1; pp. 146 - 156
• Main Authors: Dangl, M.A., Sgraja, C., Lindner, J.
• Format: Journal Article
• Language: English
• Published: Piscataway, NJ IEEE 01.01.2007; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; Blocking; Channel estimation; Channel state information; Channels; Covariance matrix; Data communication; Equalizers; Error analysis; Exact sciences and technology; Impulse response; Intersymbol interference; Mathematical models; Maximum likelihood detection; Maximum likelihood estimation; Noise; Receivers; Statistics; Studies; Symbols; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments); Fading channels; Performance evaluation; Estimation error; Parameter estimation; block equalization; Error estimation; Rayleigh channels; Transmission channel; Data transmission; Iterative method; Equalizer; Covariance matrix; Optimal detection; Equalization; Information transmission; Learning; Minimal variance; Block design; Intersymbol interference; Pulse response; Channel estimation; Maximum likelihood; constrained minimum variance filters; turbo equalization
• ISSN: 1536-1276; 1558-2248
• DOI: 10.1109/TWC.2007.04816

We consider the design of a block equalizer for an intersymbol interference channel, given that the channel impulse response is not perfectly known at the receiver. In contrast to other schemes, our receiver is designed for imperfect channel state information and incorporates the statistics of the channel estimation error. In particular, we suggest an error model for data transmission that takes the influence from the data symbols on the estimation noise into account. We derive the optimum detection rule for the considered error model according to the maximum likelihood criterion and verify that the covariance matrix of the estimation noise depends on the actual transmitted data symbols. Motivated by this result, we propose a realizable receiver structure adopting the turbo principle that exploits the data-dependency of the covariance matrix of the estimation noise. The proposed scheme outperforms conventional receivers that neglect the exact statistics of the estimation noise. The core of our receiver is a soft-input soft-output block equalizer based on constrained minimum variance filter design. We assess the performance of the proposed turbo equalization scheme for block Rayleigh fading channels, applying both one-shot training-based channel estimation and iterative data-aided channel estimation