Abstract
This article proposes a semiblind channel estimation method for multiple-input multiple-output orthogonal frequency-division multiplexing systems based on circular precoding. Relying on the precoding scheme at the transmitters, the autocorrelation matrix of the received data induces a structure relating the outer product of the channel frequency response matrix and precoding coefficients. This structure makes it possible to extract information about channel product matrices, which can be used to form a Hermitian matrix whose positive eigenvalues and corresponding eigenvectors yield the channel impulse response matrix. This article also tests the resistance of the precoding design to finite-sample estimation errors, and explores the effects of the precoding scheme on channel equalization by performing pairwise error probability analysis. The proposed method is immune to channel zero locations, and is reasonably robust to channel order overestimation. The proposed method is applicable to the scenarios in which the number of transmitters exceeds that of the receivers. Simulation results demonstrate the performance of the proposed method and compare it with some existing methods.
Highlights
Orthogonal frequency-division multiplexing (OFDM), when combined with cyclic prefix (CP) as the guard intervals, is an effective transmission technique for highspeed broadband communication systems because of its high data rate, high spectral efficiency, and lack of intersymbol interference (ISI) [1,2]
5 Conclusions In this article, we propose a semiblind channel estimation method for Multiple-input multiple-output (MIMO)–OFDM systems based on circular precoding
By taking advantage of circular precoding, we obtain the outer product of the channel impulse response matrix H from the autocorrelation matrix of the received data
Summary
Orthogonal frequency-division multiplexing (OFDM), when combined with cyclic prefix (CP) as the guard intervals, is an effective transmission technique for highspeed broadband communication systems because of its high data rate, high spectral efficiency, and lack of intersymbol interference (ISI) [1,2]. Gao et al [9] proposed a robust subspace method applicable to MIMO–OFDM systems Their method exhibits many advantages, including robustness to channel order overestimation and guaranteeing the channel identifiability. Previous studies present three typically non-redundant precoding methods for (semi)blind channel estimation for MIMO– OFDM systems [10,11,12]. Shin et al [12] presented a framework for exploiting a general non-redundant precoding method for MIMO– OFDM systems and MIMO single-carrier systems with frequency-domain equalization. Their method is robust to channel order overestimation and incurs a relaxed channel identifiability condition
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