Subspace-based blind channel estimation for OFDM by exploiting virtual carriers

Reliable channel estimation is indispensable for orthogonal frequency-division multiplexing (OFDM) systems employing coherent detection and adaptive loading in order to achieve high data rate communications. Several options exist in practical OFDM systems-including training symbols, cyclic prefix, virtual carriers, pilot tones, and receiver diversity-to facilitate channel estimation. In this paper, a subspace blind channel estimation method based on exploiting the presence of virtual carriers is proposed for OFDM systems over a time-dispersive channel. The method can be applied to conventional OFDM systems with cyclic prefix as well as OFDM systems with no cyclic prefix. The reduction/elimination of cyclic prefix thereby provides the OFDM systems the potential to achieve higher channel utilization than most previously reported cyclic prefix based estimators. Sufficient channel identifiability condition is developed as well. Comparison with two other recently reported subspace methods is presented via computer simulations to support the effectiveness of the proposed method.

[1]  Georgios B. Giannakis,et al.  Finite-alphabet based channel estimation for OFDM and related multicarrier systems , 2001, IEEE Trans. Commun..

[2]  Luc Vandendorpe,et al.  Equalization for DMT based broadband modems , 2000 .

[3]  Zhi Ding,et al.  A statistical subspace method for blind channel identification in OFDM communications , 2000, 2000 IEEE International Conference on Acoustics, Speech, and Signal Processing. Proceedings (Cat. No.00CH37100).

[4]  Hikmet Sari,et al.  Transmission techniques for digital terrestrial TV broadcasting , 1995, IEEE Commun. Mag..

[5]  Yiyan Wu,et al.  COFDM: an overview , 1995, IEEE Trans. Broadcast..

[6]  Subhasish Subhasish,et al.  Joint blind estimation of channel and data symbols in OFDM , 2000, VTC2000-Spring. 2000 IEEE 51st Vehicular Technology Conference Proceedings (Cat. No.00CH37026).

[7]  Robert W. Heath,et al.  Exploiting input cyclostationarity for blind channel identification in OFDM systems , 1999, IEEE Trans. Signal Process..

[8]  Sumit Roy,et al.  A subspace blind channel estimation method for OFDM systems without cyclic prefix , 2001, IEEE 54th Vehicular Technology Conference. VTC Fall 2001. Proceedings (Cat. No.01CH37211).

[9]  Hui Liu,et al.  A high efficiency carrier estimator for OFDM communications , 1998, Conference Record of the Thirty-First Asilomar Conference on Signals, Systems and Computers (Cat. No.97CB36136).

[10]  Per Ola Börjesson,et al.  OFDM channel estimation by singular value decomposition , 1996, Proceedings of Vehicular Technology Conference - VTC.

[11]  Marc de Courville,et al.  Blind and semi-blind channel identification methods using second order statistics for OFDM systems , 1999, 1999 IEEE International Conference on Acoustics, Speech, and Signal Processing. Proceedings. ICASSP99 (Cat. No.99CH36258).

[12]  M. de Courville,et al.  Blind equalization of OFDM systems based on the minimization of a quadratic criterion , 1996, Proceedings of ICC/SUPERCOMM '96 - International Conference on Communications.

[13]  Eric Moulines,et al.  Subspace methods for the blind identification of multichannel FIR filters , 1995, IEEE Trans. Signal Process..

[14]  Geoffrey Ye Li,et al.  Robust channel estimation for OFDM systems with rapid dispersive fading channels , 1998, IEEE Trans. Commun..

[15]  Peter Adam Hoeher,et al.  A statistical discrete-time model for the WSSUS multipath channel , 1992 .

[16]  J.A.C. Bingham,et al.  Multicarrier modulation for data transmission: an idea whose time has come , 1990, IEEE Communications Magazine.

[17]  Charles R. Johnson,et al.  Matrix analysis , 1985, Statistical Inference for Engineers and Data Scientists.

[18]  Luc Vandendorpe,et al.  A Fractionally Spaced Decision Feedback Joint Detection Proposal for Multi Carrier CDMA , 1999, Eur. Trans. Telecommun..

[19]  Xiaowen Wang,et al.  Adaptive channel estimation using cyclic prefix in multicarrier modulation system , 1999, IEEE Communications Letters.

[20]  Ali N. Akansu,et al.  A subspace method for blind channel identification in OFDM systems , 2000, 2000 IEEE International Conference on Communications. ICC 2000. Global Convergence Through Communications. Conference Record.

[21]  P. Duhamel,et al.  A subspace based blind and semi-blind channel identification method for OFDM systems , 1999, 1999 2nd IEEE Workshop on Signal Processing Advances in Wireless Communications (Cat. No.99EX304).