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Vía, Javier; Santamarı́a, Ignacio; Pérez, J.; Vielva, Luis

doi:10.1002/wcm.v10:11

Cited by 7 publications

References 163 publications

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Subspace-based semiblind channel estimation method for fast fading orthogonally coded MIMO-OFDM systems

Vinogradova

Sarmadi

Pesavento

2011

2011 4th IEEE International Workshop on Computational Advances in Multi-Sensor Adaptive Processing (CAMSAP)

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In this paper, a new semiblind spectrally efficient channel estimation method is presented for fast fading orthogonally coded multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) systems. The proposed method benefits from both the available training symbols inserted in the data frame structure of wireless standards as LTE and WiMAX and the redundancy introduced in the space-time code to enhance channel estimation quality. Our method offers a closed-form solution and performs channel estimation in the time domain in two consecutive steps. First, the subspace containing the true channel vector is estimated from the extended covariance matrix of the received data in a fully blind fashion, and then, the true channel vector is recovered from the obtained subspace using available training symbols. The parsimonious channel characterization that we use decreases the number of parameters required to be estimated. On the one hand, it results in a performance improvement as compared to the frequency domain channel estimation methods by coherent processing over all subcarriers. On the other hand, the bandwidth efficiency is enhanced by training overhead reduction as compared to the pure training-based approaches. Moreover, the proposed method is able to eliminate all nonscalar ambiguities inherent in blind channel estimation techniques in two practically important cases, the systems involving single-antenna receivers and the systems involving rotatable codes.

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Subspace-based semiblind channel estimation method for fast fading orthogonally coded MIMO-OFDM systems

Vinogradova

Sarmadi

Pesavento

2011

2011 4th IEEE International Workshop on Computational Advances in Multi-Sensor Adaptive Processing (CAMSAP)

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Closed-form blind channel estimation in orthogonally coded MIMO-OFDM systems: A simple strategy to resolve non-scalar ambiguities

Sarmadi

Pesavento

2011

2011 IEEE 12th International Workshop on Signal Processing Advances in Wireless Communications

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We consider blind channel estimation in multiple-input multipleoutput orthogonal frequency-division multiplexing (MIMO-OFDM) systems with orthogonal space-time block code (OSTBC). We introduce a novel weighted covariance matrix of the received data which exploits all redundancies contained in the code. Based on the orthogonality properties of OSTBCs, we further show that a low-rank subspace mode applies to this matrix. Assuming a delay spread over the wireless channel smaller than the OFDM symbol duration, we prove that the corresponding signal subspace in time-domain collapses to a single principal eigenvector from which the channel taps can be uniquely determined. Unlike to previous methods, which suffer from ambiguities, for example, in the case of rotatable OSTBCs, our weighted covariance approach allows to resolve all non-scalar ambiguities provided that a specific transmitted symbol exhibits a higher power than the remaining symbols.

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Noncoherent OSTBC-OFDM for MIMO and Cooperative Communications: Perfect Channel Identifiability and Achievable Diversity Order

Chang

Huang

et al. 2012

IEEE Trans. Signal Process.

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This paper considers the context of orthogonal space-time block coded OFDM (OSTBC-OFDM) without channel state information at the receiver. Assuming noncoherent maximum-likelihood detection, the interest herein lies in detection within one OSTBC-OFDM block, motivated by its capability of accommodating relatively fast block fading channels. Our investigation focuses on analysis aspects, where we seek to establish practical noncoherent BPSK/QPSK OSTBC-OFDM schemes that have provably good channel identifiability and diversity properties. We consider perfect channel identifiability (PCI), a strong condition guaranteeing unique noncoherent channel identification for any (nonzero) channel. Through a judicious design involving special OSTBCs and pilot placement, we propose an OSTBC-OFDM scheme that is PCI-achieving and consumes fewer pilots compared to conventional pilot-aided channel estimation methods. We further our analysis by showing that a PCI-achieving scheme also achieves maximal noncoherent spatial diversity for the Kronecker Gaussian spatial-temporal channel fading model, which covers the popular i.i.d. Rayleigh fading channel and a variety of correlated and sparse multipath channels. All these results are developed in parallel for the centralized point-to-point MIMO scenario and a distributed relay communication scenario. For the latter scenario, our diversity analysis shows that the PCI-achieving scheme can also achieve maximal noncoherent cooperative diversity. The performance merits of the proposed PCI-achieving scheme are demonstrated by simulations.

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Untitled

Cited by 7 publications

References 163 publications

Subspace-based semiblind channel estimation method for fast fading orthogonally coded MIMO-OFDM systems

Subspace-based semiblind channel estimation method for fast fading orthogonally coded MIMO-OFDM systems

Closed-form blind channel estimation in orthogonally coded MIMO-OFDM systems: A simple strategy to resolve non-scalar ambiguities

Noncoherent OSTBC-OFDM for MIMO and Cooperative Communications: Perfect Channel Identifiability and Achievable Diversity Order

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