Closed-form blind channel estimation for orthogonally coded MIMO-OFDM systems: An algorithm and uniqueness study

Sarmadi, Nima; Pesavento, Marius

doi:10.1109/wsa.2011.5741941

Cited by 3 publications

(21 citation statements)

References 12 publications

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“…In Fig. 2, we plot the performances of the subspace-based methods in (16) and (25), and Sarmadi's algorithm of [6]. We observe that Sarmadi's algorithm does not work in M r = 1 case.…”

Section: Simulation Resultsmentioning

confidence: 99%

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New subspace-based blind channel estimation for orthogonally coded MIMO-OFDM systems

Jiang

Lin

Phoong

2014

2014 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)

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Two novel subspace-based blind channel estimation methods for orthogonally coded multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems with more than two transmit antennas are proposed in this paper. The proposed methods exploit the null space induced by the orthogonal space-time block codes (OSTBC). They can be applied to systems with one or more receive antennas. Simulation results show that accurate estimates can be obtained.

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“…In Fig. 2, we plot the performances of the subspace-based methods in (16) and (25), and Sarmadi's algorithm of [6]. We observe that Sarmadi's algorithm does not work in M r = 1 case.…”

Section: Simulation Resultsmentioning

confidence: 99%

“…Because the approach is based on convex optimization and amounts to solving a semidefinite program (SDP), its computational cost may be rather high. In [6], the authors proposed a lower computational-complexity method. The method gives a good performance but it works only when there are more than one receive antenna.…”

Section: Introductionmentioning

confidence: 99%

New subspace-based blind channel estimation for orthogonally coded MIMO-OFDM systems

Jiang

Lin

Phoong

2014

2014 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)

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“…Training approaches that incur a penalty in terms of bandwidth efficiency are commonly used for reliable channel estimation. Recently, a promising trend is to estimate the channel using spectrally efficient blind methods [2]- [9]. Several blind estimation techniques have been proposed for flat fading channels [2]- [4] and can be applied straightforwardly in MIMO-OFDM systems in a subcarrierwise manner.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, all of these techniques require relatively long data records that makes them inapplicable in fast fading scenarios. For short time data records available at the receiver side, different approaches to blind channel estimation and/or symbol detection in orthogonally coded MIMO-OFDM systems have been developed recently [5]- [9]. The approach of [5] is only applicable to the case of BPSK and QPSK modulations, needs to be performed in a blockwise manner and can not benefit from averaging over successive blocks of received OSTBC-OFDM data.…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, the latter approaches generally yield biased channel estimates for the finite sample case and conditions under which unique channel estimates are obtained have not been provided. Moreover, the approaches [7]- [9] fail to resolve the non-scalar ambiguities associated with the channel estimation as, for example, in the case of rotatable OSTBCs including the popular Alamouti code and/or particular codes in multiple-input single-output (MISO) system configurations [10].…”

Section: Introductionmentioning

confidence: 99%

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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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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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Closed-form blind channel estimation for orthogonally coded MIMO-OFDM systems: An algorithm and uniqueness study

Cited by 3 publications

References 12 publications

New subspace-based blind channel estimation for orthogonally coded MIMO-OFDM systems

New subspace-based blind channel estimation for orthogonally coded MIMO-OFDM systems

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

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

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