Subspace-based blind and semi-blind channel estimation for OFDM systems,” (2002)

by B Muquet, M de Courville, P Duhamel
Venue:IEEE Trans. Signal Process.,
Add To MetaCart
Results 1 - 10 of 56

Cyclic Prefixing or Zero Padding for Wireless Multicarrier Transmissions?

by Bertrand Muquet, Zhengdao Wang, Georgios B. Giannakis, Marc de Courville, Pierre Duhamel , 2002
"... Zero padding (ZP) of multicarrier transmissions has recently been proposed as an appealing alternative to the traditional cyclic prefix (CP) orthogonal frequency-division multiplexing (OFDM) to ensure symbol recovery regardless of the channel zero locations. In this paper, both systems are studied t ..."
Abstract - Cited by 109 (10 self) - Add to MetaCart
Zero padding (ZP) of multicarrier transmissions has recently been proposed as an appealing alternative to the traditional cyclic prefix (CP) orthogonal frequency-division multiplexing (OFDM) to ensure symbol recovery regardless of the channel zero locations. In this paper, both systems are studied to delineate their relative merits in wireless systems where channel knowledge is not available at the transmitter. Two novel equalizers are developed for ZP-OFDM to tradeoff performance with implementation complexity. Both CP-OFDM and ZP-OFDM are then compared in terms of transmitter nonlinearities and required power backoff. Next, both systems are tested in terms of channel estimation and tracking capabilities. Simulations tailored to the realistic context of the standard for wireless local area network HIPERLAN/2 illustrate the pertinent tradeoffs.

Blind OFDM Channel Estimation through Simple Linear Precoding

by Athina Petropulu , Ruifeng Zhang, Rui Lin - IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS , 2003
"... A novel approach of blind channel estimation for OFDM systems is proposed. A linear transformation is applied on each block before it enters the OFDM system. The transform imposes a correlation structure on the transmitted blocks, which is exploited at the receiver to recover the channel via simpl ..."
Abstract - Cited by 36 (2 self) - Add to MetaCart
A novel approach of blind channel estimation for OFDM systems is proposed. A linear transformation is applied on each block before it enters the OFDM system. The transform imposes a correlation structure on the transmitted blocks, which is exploited at the receiver to recover the channel via simple cross-correlation operations. The proposed approach is computationally simple and converges fast, which makes it a good candidate for estimation of fast-varying channels. Its performance is tested analytically, through a mean-square error analysis, and also via simulations. Results show that it compares favorably to the training based scheme used in the IEEE 802.11a wireless standard.

A semi-blind channel estimation method for multi-user multi-antenna OFDM systems

by Yonghong Zeng, Tung-sang Ng - IEEE Trans. Signal Process , 2004
"... Abstract—A subspace-based blind method is proposed for esti-mating the channel responses of a multiuser and multiantenna or-thogonal frequency division multiplexing (OFDM) uplink system. It gives estimations to all channel responses subject to a scalar ma-trix ambiguity and does not need precise cha ..."
Abstract - Cited by 22 (7 self) - Add to MetaCart
Abstract—A subspace-based blind method is proposed for esti-mating the channel responses of a multiuser and multiantenna or-thogonal frequency division multiplexing (OFDM) uplink system. It gives estimations to all channel responses subject to a scalar ma-trix ambiguity and does not need precise channel order informa-tion (only an upper bound for the orders is required). Furthermore, the scalar ambiguity matrix can be easily resolved by using only one pilot OFDM block, given that the number of users is smaller than the number of symbols in the pilot symbol block. Equalization methods are discussed based on the estimated channels. By using partial knowledge of the channels, a multipath subspace method is proposed that reduces the computational complexity. Simulations show that the methods are effective and robust. Index Terms—Blind channel identification, MIMO, mul-tiantenna, multiuser, OFDM, semi-blind, subspace method, zero-padding.
(Show Context)

and C.Tellambura, “Joint channel estimation and data detection for OFDM systems via sphere decoding

by Tao Cui, Chintha Tellambura - in Proc. of GLOBECOM , 2004
"... Abstract — We develop blind and semi-blind joint estimators of the channel impulse response (CIR) and data symbols for Orthogonal Frequency Division Multiplexing (OFDM) systems over a frequency selective fading channel. Using the maximum likelihood (ML) criterion, we derive two estimators for the tr ..."
Abstract - Cited by 18 (3 self) - Add to MetaCart
Abstract — We develop blind and semi-blind joint estimators of the channel impulse response (CIR) and data symbols for Orthogonal Frequency Division Multiplexing (OFDM) systems over a frequency selective fading channel. Using the maximum likelihood (ML) criterion, we derive two estimators for the transmit data symbols that require minimizing a complex, integer quadratic xTGx ∗ where x is a data vector and the matrixG characterizes each estimator. Avoiding computationally prohibitive exhaustive search, we use both sphere decoding (SD) and V-BLAST algorithms. We also modify SD algorithm to our complex OFDM system to handle any M-PSK and incorporate a reduced complexity SD into OFDM system. The quadratic for the blind estimator suffers from rank deficiency. We give an efficient solution to the rank deficiency problem. Simulation results confirm good performance of our proposed estimators. I.
(Show Context)

Totally blind channel estimation for OFDM on fast varying mobile radio channels

by Marc C. Necker, Gordon L. Stüber - IEEE Trans. on Wireless Comm , 2004
"... Abstract — A new blind channel estimation scheme for OFDMsystems is proposed based on the ML-principle. By avoiding the use of second- and higher-order statistics, a very fast convergence rate is achieved. A novel approach is also proposed for resolving the phase ambiguity of the blind channel estim ..."
Abstract - Cited by 15 (0 self) - Add to MetaCart
Abstract — A new blind channel estimation scheme for OFDMsystems is proposed based on the ML-principle. By avoiding the use of second- and higher-order statistics, a very fast convergence rate is achieved. A novel approach is also proposed for resolving the phase ambiguity of the blind channel estimate without the need for any reference symbols. The approach combines different modulation schemes on adjacent subcarriers, such as 3-PSK and QPSK, to resolve phase ambiguity. Simulations were performed for mobile radio environments with high Doppler frequencies and short-to-medium delay spreads. The achieved performance is comparable to that of pilot-based channel estimation for the case of QPSK-modulation.
(Show Context)

EVD-based channel estimations for multicell multiuser MIMO with very large antenna arrays

by Hien Quoc Ngo, Erik G. Larsson, Post Print, Hien Quoc, Ngo Erik, G. Larsson - Proceedings of IEEE International Conference on Acoustics, Speech and Signal Processing , 2012
"... N.B.: When citing this work, cite the original article. ©2012 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to ..."
Abstract - Cited by 13 (0 self) - Add to MetaCart
N.B.: When citing this work, cite the original article. ©2012 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.
(Show Context)

Joint data detection and channel estimation for OFDM systems

by Tao Cui, Student Member, Chintha Tellambura, Senior Member - IEEE Trans. Commun , 2006
"... Abstract—We develop new blind and semi-blind data detec-tors and channel estimators for orthogonal frequency-division multiplexing (OFDM) systems. Our data detectors require min-imizing a complex, integer quadratic form in the data vector. The semi-blind detector uses both channel correlation and no ..."
Abstract - Cited by 12 (2 self) - Add to MetaCart
Abstract—We develop new blind and semi-blind data detec-tors and channel estimators for orthogonal frequency-division multiplexing (OFDM) systems. Our data detectors require min-imizing a complex, integer quadratic form in the data vector. The semi-blind detector uses both channel correlation and noise variance. The quadratic for the blind detector suffers from rank deficiency; for this, we give a low-complexity solution. Avoiding a computationally prohibitive exhaustive search, we solve our data detectors using sphere decoding (SD) and V-BLAST and provide simple adaptations of the SD algorithm. We consider how the blind detector performs under mismatch, generalize the basic data detectors to nonunitary constellations, and extend them to systems with pilots and virtual carriers. Simulations show that our data detectors perform well. Index Terms—Channel estimation, orthogonal frequency-divi-sion multiplexing (OFDM), sphere decoding (SD). I.
(Show Context)

Moustakides, “Fast and Stable Subspace Tracking,” sumbitted to the

by Xenofon G. Doukopoulos, George V. Moustakides, Senior Member - IEEE Trans. Sig. Proc
"... Abstract—We consider the problem of adaptive subspace tracking, when the rank of the subspace we seek to estimate is assumed to be known. Starting from the Data Projection Method (DPM), which constitutes a simple and reliable means for adap-tively estimating and tracking subspaces, we develop a fast ..."
Abstract - Cited by 11 (1 self) - Add to MetaCart
Abstract—We consider the problem of adaptive subspace tracking, when the rank of the subspace we seek to estimate is assumed to be known. Starting from the Data Projection Method (DPM), which constitutes a simple and reliable means for adap-tively estimating and tracking subspaces, we develop a fast and numerically robust implementation of DPM, which comes at a considerably lower computational cost. Most existing schemes track subspaces corresponding either to the largest or to the smallest singular values, while our DPM version can switch from one subspace type to the other with a simple change of sign of its single parameter. The proposed algorithm provides orthonormal vector estimates of the subspace basis that are numerically stable since they do not accumulate roundoff errors. In fact, our scheme constitutes the first numerically stable, low complexity, algorithm for tracking subspaces corresponding to the smallest singular values. Regarding convergence towards orthonormality our scheme exhibits the fastest speed among all other subspace tracking algorithms of similar complexity. Index Terms—Fast adaptive algorithms, numerically stable sub-space tracking, orthogonal iteration, subspace tracking. I.
(Show Context)

Channel estimation for MIMO-OFDM systems by modal analysis/filtering

by Marcello Cicerone, Osvaldo Simeone, Umberto Spagnolini, Senior Member - IEEE Trans. Commun , 2006
"... Abstract—In this paper, we investigate the benefits of exploiting the a priori information about the structure of the multipath channel on the performance of channel estimation for multiple-input multiple-output–orthogonal frequency-division multiplexing (MIMO-OFDM) systems. We first approach this p ..."
Abstract - Cited by 7 (0 self) - Add to MetaCart
Abstract—In this paper, we investigate the benefits of exploiting the a priori information about the structure of the multipath channel on the performance of channel estimation for multiple-input multiple-output–orthogonal frequency-division multiplexing (MIMO-OFDM) systems. We first approach this problem from the point of view of estimation theory by computing a lower bound on the estimation error and studying its properties. Then, based on the insight obtained from the analysis, efficient channel estimators are designed that perform close to the derived limit. The proposed channel estimators compute the long-term features of the multipath channel model through a subspace tracking algorithm by identifying the invariant (over multiple OFDM symbols) space/time modes of the channel (modal analysis). On the other hand, the fast-varying fading amplitudes are tracked by using least-squares techniques that exploit temporal correlation of the fading process (modal filtering). The analytic treatment is complemented by thorough numerical investigation in order to validate the performance of the proposed techniques. MIMO-OFDM with bit-interleaved coded modulation and MIMO-turbo equalization is selected as a benchmark for performance evaluation in terms of bit-error rate. Index Terms—Adaptive estimation, communication systems performance, fading channels, frequency-division multiplexing, multiple-input multiple-output (MIMO) systems. I.
(Show Context)

Linear Block Precoding For Blind Channel Estimation In Ofdm Systems

by Rui Lin, Athina P. Petropulu - in OFDM Systems,” Seventh International Symposium on Signal Processing and Its Applications (ISSPA 2003 , 2003
"... We propose a novel approach for blind channel estimation over frequency selective channels in OFDM system. By introducing a non-redundant unitary precoder for each pair of blocks before they enter the OFDM system, the channel can be identified up to a complex scalar ambiguity based upon a simple cro ..."
Abstract - Cited by 5 (2 self) - Add to MetaCart
We propose a novel approach for blind channel estimation over frequency selective channels in OFDM system. By introducing a non-redundant unitary precoder for each pair of blocks before they enter the OFDM system, the channel can be identified up to a complex scalar ambiguity based upon a simple cross-correlation operations applied to successive received signal blocks. It is shown that the proposed approach not only maintains the transmission power, but also provides multipath diversity and bandwidth efficiency.